Communication apparatus and communication method for multi-link address resolution

Abstract

The present disclosure provides a communication apparatus and method for multi-link address resolution, the communication apparatus being a communication apparatus of a plurality of communication apparatuses attached to a first multi-link device (MLD), the communication apparatus comprising: a receiver configured to receive, from a requesting communication apparatus, a first data frame carrying an address resolution request, the address resolution request carrying an internet protocol address of the first MLD; and circuitry configured to determine whether the requesting communication apparatus is attached to a second MLD and to generate a second data frame carrying an address resolution response, the address resolution response carrying a medium access control (MAC) address of the communication apparatus in response to a determination that the requesting communication apparatus is not attached to the second MLD, or the address resolution response carrying an MLD MAC address of the first MLD in response to a determination that the requesting communication apparatus is attached to the second MLD.

Description

Technical Field

[0001] This embodiment generally relates to communication devices, and more specifically to methods and apparatus for multi-link address resolution. Background Technology

[0002] In today's world, communication devices are expected to operate wirelessly with the same capabilities as wired computing devices. For example, users expect to seamlessly stream high-definition movies to their wireless communication devices. This presents challenges for both the communication devices and the access points to which they are wirelessly connected.

[0003] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 Group recently established the 802.11 Task Group (TG) to address these challenges. Multilink operation in the 2.4 GHz, 5 GHz, and 6 GHz bands has been identified as a key candidate technology for this type of communication. Multichannel aggregation on multiple links is a natural way to create a significant increase in communication data throughput.

[0004] To enable this multi-link operation between an Access Point (AP) Multilink Device (MLD) and a non-AP MLD, a multilink establishment can be performed on one of the supported links to establish an association for a Subsidiary Station (STA) in one or more links.

[0005] However, to date, there has been no discussion on supporting multi-link address resolution for traditional STAs to resolve peer link-layer addresses (e.g., MAC addresses) from a given Internet layer address (e.g., IP address) in the context of MLD.

[0006] Therefore, there is a need for communication devices and methods capable of solving the aforementioned problems. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and appended claims, in conjunction with the accompanying drawings and the background information of this disclosure. Summary of the Invention

[0007] Non-limiting and exemplary embodiments help to provide communication apparatus and communication methods for multi-link address resolution.

[0008] In a first aspect, this disclosure provides a communication device among a plurality of communication devices attached to a first multi-link device (MLD), the communication device comprising: a receiver for receiving from a requesting communication device a first data frame carrying an address resolution request, the address resolution request carrying an Internet Protocol (IP) address of the first MLD; circuitry for determining whether the requesting communication device is attached to a second MLD; and generating a second data frame carrying an address resolution response, the address resolution response carrying a Media Access Control (MAC) address of the communication device in response to determining that the requesting communication device is not attached to the second MLD, or the address resolution response carrying an MLD MAC address of the first MLD in response to determining that the requesting communication device is attached to the second MLD.

[0009] In a second aspect, this disclosure provides an AP (Access Point) associated with an AP MLD (Multi-Access Point LD), the AP comprising: a receiver receiving a first data frame carrying an address resolution request from a requesting communication device, the address resolution request carrying an IP address of a first MLD associated with the AP MLD, the first MLD including a plurality of communication devices; circuitry determining whether the requesting communication device is associated with a second MLD associated with the AP MLD; and generating a second data frame carrying an address resolution response, in response to determining that the requesting communication device is not associated with the second MLD, the address resolution response carrying a MAC address of one of the plurality of communication devices associated with the first MLD, or in response to determining that the requesting communication device is associated with the second MLD, the address resolution response carrying an MLD MAC address of the first MLD.

[0010] In a third aspect, this disclosure provides a communication method, comprising: receiving from a requesting communication device a first data frame carrying an address resolution request, the address resolution request carrying an IP address of a first MLD; determining whether the requesting communication device is attached to a second MLD; and generating a second data frame carrying an address resolution response, in response to determining that the requesting communication device is not attached to the second MLD, the address resolution response carrying a MAC address of a communication device among a plurality of communication devices attached to the first MLD, or in response to determining that the requesting communication device is attached to the second MLD, the address resolution response carrying an MLD MAC address of the first MLD.

[0011] Additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. These benefits and / or advantages may be obtained individually from the various embodiments and features in the specification and drawings, and not all of them need to be provided to obtain one or more of such benefits and / or advantages. Attached Figure Description

[0012] The accompanying drawings are used to illustrate various embodiments and explain the principles and advantages of these embodiments, wherein similar reference numerals refer to the same or functionally similar elements throughout the separate views, and the drawings, together with the following detailed description, are incorporated into and form part of the specification.

[0013] Figure 1 A schematic diagram illustrating the proxy ARP characteristics of an access point (AP) is shown.

[0014] Figure 2 The configuration of MLD is shown.

[0015] Figure 3 The diagram illustrates direct link communication between an AP in an AP-MLD and a STA that is attached to or not attached to a non-AP MLD.

[0016] Figure 4 An example configuration of a communication apparatus according to this disclosure is shown. According to this disclosure, the communication apparatus can be implemented as an access point (AP) and a station (STA), and is configured for multi-link address resolution.

[0017] Figure 5 A flowchart 500 illustrating a communication method according to this disclosure is shown.

[0018] Figure 6A The diagram illustrates an example configuration of an AP MLD for multi-link address resolution according to a first embodiment of the present disclosure, and a schematic diagram of communication between the network interface layer of the AP MLD and its Internet layer.

[0019] Figure 6B The diagram illustrates an example configuration of a non-AP MLD for multi-link address resolution according to a first embodiment of the present disclosure, and a schematic diagram of communication between the network interface layer of the non-AP MLD and its Internet layer.

[0020] Figure 7 A flowchart illustrating communication between an AP MLD and a non-AP MLD for multi-link address resolution according to a first embodiment of the present disclosure is shown.

[0021] Figure 8 A flowchart illustrating communication between two non-APMLDs via AP MLD for multi-link address resolution according to a first embodiment of the present disclosure is shown.

[0022] Figure 9 and Figure 10 Two flowcharts illustrating communication via AP MLD between a non-AP MLD and a non-MLD STA for multi-link address resolution according to a first embodiment of the present disclosure are shown.

[0023] Figure 11A The diagram illustrates an example configuration of an AP-MLD for multi-link address resolution according to a second embodiment of the present disclosure, and a schematic diagram of communication between the network interface layer of the AP MLD and its Internet layer.

[0024] Figure 11B The diagram illustrates an example configuration of a non-AP-MLD for multi-link address resolution according to a second embodiment of the present disclosure, and a schematic diagram of communication between the network interface layer of the non-AP MLD and its Internet layer.

[0025] Figure 12 An example format of a data frame according to a second embodiment of the present disclosure is shown.

[0026] Figure 13 A flowchart illustrating communication between an AP MLD and a non-MLD STA for multi-link address resolution according to a second embodiment of the present disclosure is shown.

[0027] Figures 14-17 Four flowcharts illustrating communication via AP MLD between non-AP MLD and non-MLD STA for multi-link address resolution according to a second embodiment of the present disclosure are shown.

[0028] Figure 18 A flowchart illustrating communication between two non-AP MLDs via an AP MLD for multi-link address resolution according to a third embodiment of the present disclosure is shown.

[0029] Figure 19 An example format of an MLD address query request frame and an MLD address query response frame according to a third embodiment of the present disclosure is shown.

[0030] Figure 20 An example format of an Ethernet type 89-0d data frame carrying an MLD address query frame is shown according to a third embodiment of the present disclosure.

[0031] Figure 21 An example architecture of the MAC address of a STA or MLD according to a fourth embodiment of this disclosure is shown.

[0032] Figure 22 A flowchart illustrating communication between two non-AP MLDs via an AP MLD for multi-link address resolution according to a fourth embodiment of the present disclosure is shown.

[0033] Figure 23 A flowchart illustrating communication via AP MLD between non-APMLD and non-MLD STAs for multi-link address resolution according to a fourth embodiment of the present disclosure is shown.

[0034] Figure 24A A flowchart illustrating communication between a distribution system, an AP MLD, and a non-AP MLD for multi-link address resolution according to a fifth embodiment of the present disclosure is shown.

[0035] Figure 24B A flowchart illustrating communication between a distribution system, an AP MLD, and a non-MLD STA for multi-link address resolution according to a fifth embodiment of the present disclosure is shown.

[0036] Figure 25 A flowchart illustrating communication via AP MLD between non-APMLD and non-MLD STAs for multi-link address resolution according to a fifth embodiment of the present disclosure is shown.

[0037] Figure 26 A flowchart illustrating communication between two non-AP MLDs via an AP MLD for multi-link address resolution according to a fifth embodiment of the present disclosure is shown.

[0038] Figures 27-30 Four flowcharts illustrating communication via AP MLD between non-AP MLD and non-MLD STA for multi-link address resolution according to a fifth embodiment of the present disclosure are shown.

[0039] Figure 31 An exemplary configuration of a communication device and two communication devices attached to the communication device is shown. According to this disclosure, the communication device is implemented as an AP MLD, and each of the attached communication devices can be implemented as an AP configured for multi-link address resolution.

[0040] Figure 32 An exemplary configuration of a communication device and two communication devices attached to the communication device is shown. According to this disclosure, the communication device is implemented as a non-AP MLD, and each of the attached communication devices may be implemented as a STA configured for multi-link address resolution.

[0041] Those skilled in the art will understand that the elements in the diagrams are shown for simplicity and clarity and are not necessarily depicted to scale. For example, the size of some elements in the illustrations, block diagrams, or flowcharts may be exaggerated relative to other elements to aid in accurate understanding of this embodiment. Detailed Implementation

[0042] The following detailed description is exemplary in nature only and is not intended to limit the embodiments or their application and use. Furthermore, it is not intended to be limited to any theory presented in the foregoing background or specific embodiments. Moreover, other desirable features and characteristics will become apparent from the following detailed description and the appended claims, in conjunction with the accompanying drawings and the background of this disclosure.

[0043] In the context of IEEE 802.11 (Wi-Fi) technology, a station is a communication device capable of using the 802.11 protocol; stations are interchangeably referred to as STAs. Based on the IEEE 802.11-2016 definition, an STA can be any device that includes IEEE 802.11-compliant Media Access Control (MAC) and a physical layer (PHY) interface to the wireless medium (WM).

[0044] For example, an STA can be a laptop computer, desktop PC, personal digital assistant (PDA), access point, or Wi-Fi phone in a wireless local area network (WLAN) environment. STAs can be fixed or mobile. In a WLAN environment, the terms "STA," "wireless client," "user," "user equipment," and "node" are often used interchangeably.

[0045] Similarly, in the context of IEEE 802.11 (Wi-Fi) technology, an AP, which can be interchangeably referred to as a Wireless Access Point (WAP), is a communication device that allows STAs in a WLAN to connect to a wired network. An AP is typically connected to a router as a standalone device (via a wired network), but it can also be integrated with or incorporated into a router.

[0046] As mentioned above, a STA in a WLAN can function as an AP at different times, and vice versa. This is because, in the context of IEEE 802.11 (Wi-Fi) technology, a communication device can include both STA and AP hardware components. In this way, the communication device can switch between STA and AP modes based on actual WLAN conditions and / or requirements.

[0047] Address Resolution Protocol (ARP) is used to discover the link-layer address (e.g., MAC address) of a peer device when its Internet layer (e.g., IP address) is known. Each device maintains a temporary "ARP cache" of this discovered mapping between IPv4 addresses and MAC addresses. The following steps are performed in ARP:

[0048] 1. Source device checks cache: The source device will first check its cache to determine if it already has the resolution for the destination device. If it does, it can skip to the last step of this process, step #9.

[0049] 2. The source device generates an ARP request message: The source device generates an ARP request message. It uses its own data link layer address as the sender hardware address (SHA) and its own IP address as the sender protocol address (SPA). The source device fills in the destination IP address with the destination protocol address. (It must leave the destination hardware address blank, as this is what it is trying to determine!)

[0050] 3. Source device broadcasts ARP request message: The source device broadcasts an ARP request message on the local network.

[0051] 4. Local device processing of ARP request messages: This message is received by every device on the local network. The message is processed, and each device searches for a match for the target protocol address. Devices that do not match discard the message and take no further action.

[0052] 5. Destination device generates ARP reply message (unicast): A device whose IP address matches the target protocol address of the message will generate an ARP reply message. This device retrieves the sender's hardware address and sender's protocol address fields from the ARP request message and uses these fields as the values ​​for the target hardware address and target protocol address in the reply. Then, the device fills in its own Layer 2 address as the sender's hardware address and its own IP address as the sender's protocol address.

[0053] 6. Destination Device Updates ARP Cache: If the source now needs to send an IP datagram to the destination, it makes sense that the destination might need to send a response to the source at some point in the near future (after all, most communication on a network is bidirectional). As an optimization, the destination device will add an entry to its own ARP cache containing the hardware and IP address of the source that sent the ARP request. This prevents the destination from performing unnecessary resolution loops later. This can be called an opportunistic ARP cache update.

[0054] 7. Destination device sends ARP reply message: The destination device sends an ARP reply message. However, this reply is unicast to the source device because it does not need to be broadcast.

[0055] 8. Source device processes ARP reply messages: The source device processes replies from the destination. The source device stores the sender's hardware address as the destination's Layer 2 address for sending its IP datagrams.

[0056] 9. Source device updates ARP cache: The source device updates its ARP cache using the sender protocol address and sender hardware address for future use when sending to this device.

[0057] ARP probing uses an ARP request constructed with all-zero SPAs. Before using an IPv4 address (whether manually configured, received via DHCP, or through some other means), a host implementing this specification must test whether the address is already in use by broadcasting ARP probe packets. The target IP address is set to the IP address being probed. If an ARP reply is received, the IP address is already in use by another device.

[0058] Neighbor Discovery (ND) can be used to achieve a similar result to ARP, but it is used for IPv6 address and MAC address mapping. ND messages are carried in ICMP packets.

[0059] Address resolution in IPv6 remains dynamic and relies on the use of a cache table that maintains pairings between IPv6 addresses and hardware addresses. Each device on the physical network keeps track of this information for its neighbors. When a source device needs to send an IPv6 datagram to its local network neighbor but does not have its hardware address (e.g., MAC address), the source device initiates the address resolution process.

[0060] For example, device A is a soliciting device attempting to send a message to device B. Instead of sending an ARP request message (Internet Control Message Protocol (ICMP) type = 135), device A generates an ND Neighbor Request message. If the underlying data link protocol, like Ethernet, supports multicast, the neighbor request message is not broadcast. Instead, the neighbor request message is sent to the requesting node address of the device whose IPv6 address we are trying to resolve. Device A does not broadcast the message; instead, it multicasts the message to the requesting node multicast address of device B. The ND Neighbor Request message can indicate ICMP type 135, the IP address of device B (the device to be resolved) in the destination address field, and the L2 address (e.g., MAC address) of the sender (i.e., device A).

[0061] Device B will receive the ND Neighbor Request message and respond to Device A with a Neighbor Advertisement message (ICMP type = 136) (unicast). This is similar to an ARP reply / response frame, informing Device A of B's ​​physical address. Device A then adds Device B's information to its neighbor cache. For efficiency, cross-referencing is also supported, as in IPv4 address resolution. Assuming Device A knows the L2 address, this is done by having Device A include its own Layer 2 (L2) address in the Neighbor Request message. Device B will then record this L2 address along with A's IP address in Device B's neighbor cache.

[0062] A requesting node multicast address is a special mapping created by each device on a multicast network based on its unicast address. The requesting node address is not unique for every IPv6 address, but the probability of any two neighbors on a given network having the same address is small. Each device receiving a multicast neighbor request message must still check to ensure it is the same device from which the source was trying to resolve its address. (This is similar to how multicast is handled in IPv4, where 32 different IP addresses could share a multicast MAC address.)

[0063] Additionally, the Proxy ARP feature is an optional Wireless Network Management (WNM) feature that allows the AP to respond to ARP requests (IPv4) or neighbor request messages (IPv6) on behalf of the associated STAs, where the AP maintains hardware addresses (e.g., MAC addresses) to Internet addresses (e.g., Internet Protocol (IP) addresses) for each associated station.

[0064] Figure 1 A schematic diagram 100 illustrates the proxy ARP characteristics of Access Point (AP) 102. AP 102 receives an ARP request from an associated STA (e.g., STA1 104) or from Distribution System (DS) 106, the ARP request having a target IP address corresponding to another associated STA (e.g., STA2 108). If the target IP address to be resolved is the IPv4 address of that other associated STA (e.g., STA2 108), then upon receiving the ARP request packet, AP 102 generates an ARP response packet, inserting the MAC address of that other associated STA (e.g., STA2 108) as the sender's MAC address into the ARP response packet. Similarly, when the target IP address to be resolved is the IPv6 address of another associated STA (e.g., STA2 108), upon receiving a Neighbor Request message, AP 102 will respond on behalf of that other associated STA (e.g., STA2 108) with a Neighbor Advertisement message (Section 4.4 of IETF RFC (Internet Engineering Task Force Comment) 4861), which carries the MAC address of the other associated STA (e.g., STA2 108) as the sender's MAC address.

[0065] ARP request packets and neighbor request messages are typically broadcast across the entire Layer 2 (L2) domain. Leveraging the proxy ARP feature, AP102 advantageously reduces the number of broadcast frames in the Basic Service Set (BSS).

[0066] It is evident that due to the assumptions made regarding ARP / ND operations on MLD, an address mismatch exists during Tunnel Direct Link Establishment (TDLS) and TDLS Direct Link Communication. Based on IEEE 802.11 submission (IEEE 802.11-2 / 1692r2), the following solution is proposed to address the address mismatch during TDLS establishment and TDLS Direct Link Communication:

[0067] • For frames sent directly to TDLS peer STAs, set the sender address (TA) field to the MAC address of the non-AP MLD;

[0068] • Use the MLD MAC address in the link identifier element; and

[0069] • Use the MLD MAC address during the TDLS peer key (TPK) handshake.

[0070] Figure 2 The configuration of MLD 200 is shown. According to the 802.11be document 0.3 (D0.3) specification, a multi-link device (MLD) (e.g., AP MLD 200) is a device with more than one affiliated AP (or STA) (e.g., AP1 202 and AP2 204) and a single MAC SAP 206 connected to a logical link control (LLC) that includes a MAC data service. The value of the Address 2 (Sender Address (TA)) field in the MAC header of frames sent by the AP over-the-air will be the MAC address of the sending AP (e.g., AP1 202 and AP2 204) associated with the MLD 200 corresponding to that link (e.g., Link 1 208, Link 2 210). Except for the individual / group bits, it is set to 1 when the TA field value is a bandwidth signaling TA, and otherwise set to 0. Similarly, the value of the Address 1 (Receiver Address (RA)) field in the MAC header of a separate addressing frame sent to the AP via over-the-air download will be the MAC address of the receiving AP (e.g., AP1 202 and AP2 204) associated with the MLD corresponding to that link (e.g., link 1 208, link 2 210).

[0071] However, the above definition / addressing rules apply to EHT MLDs. EHT APs are also High Efficiency (HE) / Very High Throughput (VHT) / High Throughput (HT) APs and require support for traditional STAs (HE / VHT / HT STAs). Traditional STAs do not understand the concept of MLD MAC addresses. Instead, they will only know the BSSID (i.e., L2 MAC address) of the AP associated with them. This may also be the case for non-MLD EHT STAs that are EHT STAs but not affiliated with an MLD.

[0072] Figure 3 A schematic diagram 300 illustrates communication between APs 304 and 306 attached to AP-MLD 302 and non-MLD STA 342, as well as STAs 324 and 326 attached to non-AP MLD 322. Each MLD (i.e., AP MLD 302 or non-AP MLD 322) has a single MAC SAP 308, 328. If MAC SAP 308, 328 is bound to their respective MLD MAC addresses 310, 330, their IP addresses will be mapped to the corresponding MLD MAC addresses. Here, it is assumed that non-AP MLD 322 is associated with AP MLD 302, and non-MLD STA 342 is associated with AP 306.

[0073] In other words, APs 304 and 306 of AP MLD 302 can communicate directly with STAs 324 and 326 (not AP MLD 322) via Link 1 350 and Link 2 352, respectively, while AP2 306 can also communicate directly with traditional STA342 via Link 2 352. ARP / ND can be initiated by the source device to discover the destination device's MAC address through ARP / ND queries and message exchange before direct link communication, or for communication via the AP. However, since the IP address included in the ARP / ND query maps to the MLD MAC address, by default, only the MLD MAC address will be returned to all ARP / ND queries, not the AP or STA MAC address. Thus, the MLD MAC address will be indicated in the RA field of frames sent on the direct link between STA326 and STA342, but these STAs can recognize that they are not the intended recipients of the frame (because they expect their STA MAC address to be indicated in the RA field), resulting in the frames sent on the direct link being dropped.

[0074] Therefore, there is a need for communication apparatuses and methods that provide feasible technical solutions for multi-link address resolution to address one or more of the challenges mentioned above. In the various embodiments described below, the communication apparatuses and methods seek to address how MLDs should perform ARP and handle address resolution from traditional STAs.

[0075] In various embodiments of this disclosure, a multi-link device (MLD) can refer to a device operating in two or more frequency bands or links (2.4 GHz, 5 GHz, or 6 GHz). An MLD may include two or more communication devices corresponding to two or more links, each operating in a specific frequency band or link. For simplicity, each link of the MLD shown in this disclosure relates to one of a plurality of communication devices attached to the MLD, which is primarily configured to operate in a specific frequency band (2.4 GHz, 5 GHz, or 6 GHz) to transmit / receive signals to / from another communication device not attached to the MLD, which also operates in that specific frequency band.

[0076] In various embodiments of this disclosure, a non-MLD STA may refer to a conventional (HE / VHT / HT) STA or an EHT STA that is not attached to an MLD. Similarly, a non-MLD AP may refer to an EHT AP that is not attached to an MLD.

[0077] In various embodiments of this disclosure, the term "L2 MAC address" refers to the MAC address of the sending / receiving STA or AP; while the term "MLD MAC address" refers to the MAC address representing an MLD. For simplicity, the letter "M" may be appended to the device name (e.g., STA, AP, or MLD) to represent the device's MAC address. For example, the MLD MAC addresses of an AP MLD and a non-AP MLD are represented as "AP-MLD-M" and "STA-MLD-M," respectively. When there are two non-AP MLDs named "Non-AP MLD1" and "Non-AP MLD2," their MLD MAC addresses will be represented as "STA-MLD1-M" and "STA-MLD2-M," respectively. Similarly, the MAC addresses of an AP and a STA are represented as "AP-M" and "STA-M," respectively. When there are two APs and two STAs named "AP1," "AP2," "STA1," and "STA2," their MAC addresses will be represented as "AP1-M," "AP2-M," "STA1-M," and "STA2-M," respectively.

[0078] In this disclosure, similar notation is applied to IP addresses. Specifically, the letters "IP" are appended to the device name (e.g., STA, AP, or MLD) to indicate the device's IP address. For example, the IP addresses of an AP MLD and a non-AP MLD are represented as "AP-MLD-IP" and "STA-MLD-IP," respectively. When two non-AP MLDs are named "Non-AP MLD1" and "Non-AP MLD2," their IP addresses will be represented as "STA-MLD1-IP" and "STA-MLD2-IP," respectively. Similarly, the IP addresses of APs and STAs (whether or not they are attached to an MLD) are represented as "AP-IP" and "STA-IP," respectively. When two APs and two STAs are named "AP1," "AP2," "STA1," and "STA2," their IP addresses will be represented as "AP1-IP," "AP2-IP," "STA1-IP," and "STA2-IP," respectively.

[0079] In various embodiments of this disclosure, data frames can be used and exchanged between the STA and AP to resolve ARP / ND queries. Data frames may include a Receiver Address (RA) field, a Sender Address (TA) field, a Destination Address (DA) field, and / or a Source Address (SA) field. The RA field declares the MAC address of the next direct receiver to which the data frame is being sent. The TA field declares the MAC address of the direct sender of the data frame. The DA field declares the MAC address of the data frame's destination. The SA field declares the MAC address of the original sender of the data frame.

[0080] To resolve ARP queries, data frames can also carry ARP messages (ARP requests or ARP replies) that include a source hardware (Src.Hw.) field, a source IP (Src.IP.) field, a destination hardware (Hw.) field, and a destination IP field. The source hardware field declares the MAC address of the sender of the message. The source IP field declares the IP address of the sender of the message. The destination hardware field declares the MAC address of the recipient to whom the message is sent. The destination IP field declares the IP address of the recipient to whom the message is sent.

[0081] To resolve ND queries, data frames can also carry ND messages (Neighbor Request Messages or Neighbor Advertisement Messages). Neighbor Request Messages include a type field (value 135), a destination address field, and a source L2 address field indicating the L2 MAC address of the sender. Neighbor Advertisement Messages include a type field (value 136), a destination address field, and a destination L2 address field indicating the L2 MAC address of the receiver to which the message is sent.

[0082] In the following paragraphs, certain exemplary embodiments are explained with reference to AP multilink devices (MLDs) in the context of EHT MLDs and conventional (HE / VHT / HT) STAs, and multilink address resolution in non-AP MLDs and / or non-MLD STAs.

[0083] Figure 4 An example configuration of a communication apparatus according to this disclosure is shown. According to this disclosure, the communication apparatus can be implemented as an AP and a STA, and configured for multi-link address resolution. Figure 4 As shown, the communication device 400 may include circuitry 414, at least one radio transmitter 402, at least one radio receiver 404, and at least one antenna 412 (for simplicity, in...). Figure 4 (Only one antenna is depicted for illustrative purposes). Circuit 414 may include at least one controller 406 for software and hardware-assisted execution of tasks designed to be performed by the controller 406, including controlling communication with one or more other communication devices in a multiple-input multiple-output (MIMO) wireless network. Circuit 414 may also include at least one transmit signal generator 408 and at least one receive signal processor 410. The at least one controller 406 may control the at least one transmit signal generator 408 for generating MAC frames (e.g., data frames, management frames, and action frames) to be transmitted via at least one radio transmitter 402, and the at least one receive signal processor 410 for processing MAC frames (e.g., data frames, management frames, and action frames) received via at least one radio receiver 404 from one or more other communication devices. Figure 4 As shown, at least one transmit signal generator 408 and at least one receive signal processor 410 may be independent modules of the communication device 400, communicating with at least one controller 406 for the functions described above. Alternatively, at least one transmit signal generator 408 and at least one receive signal processor 410 may be included in at least one controller 406. Those skilled in the art will understand that the arrangement of these functional modules is flexible and can vary according to actual needs and / or requirements. Data processing, storage, and other related control devices may be provided on suitable circuit boards and / or chipsets. In various embodiments, when in operation, at least one radio transmitter 402, at least one radio receiver 404, and at least one antenna 412 may be controlled by at least one controller 406.

[0084] Communication device 400 provides the functionality required for multi-link address resolution. For example, communication device 400 may be a STA attached to a first MLD, and at least one radio receiver 404 of communication device 400 may receive a first data frame carrying an address resolution request from a requesting communication device (e.g., a non-MLD STA or a non-AP MLD STA), the address resolution request carrying the Internet Protocol (IP) address of the first MLD. Circuit 414 (e.g., at least one receive signal processor 410 of circuit 414) may process the first data frame and determine whether the requesting communication is attached to a second MLD. Circuit (e.g., at least one transmit signal generator 408 of circuit 414) may generate a second data frame carrying an address resolution response (i) in response to determining that the requesting communication device is not attached to the second MLD and carries the Media Access Control (MAC) address of communication device 400, or (ii) in response to determining that the requesting communication device is attached to the second MLD and carries the MAC address of the first MLD. Radio transmitter 402 may, for example, transmit the second data frame to the requesting communication device.

[0085] For example, communication device 400 may be an AP attached to an AP MLD, which is equipped with a proxy ARP feature to respond to ARP requests on behalf of an associated STA (e.g., a non-MLD STA or a STA of a first non-AP MLD associated with the AP MLD). At least one radio receiver 404 of communication device 400 may receive a first data frame carrying an address resolution request from the requesting communication device (e.g., a non-MLD STA or a second non-AP MLD STA), the address resolution request carrying the IP address of the first MLD associated with the AP MLD. Circuitry 414 (e.g., at least one receive signal processor 410 of circuitry 414) may process the first data frame and determine whether the requesting communication is attached to a second MLD. The circuitry (e.g., at least one transmit signal generator 408 of circuitry 414) can generate a second data frame carrying an address resolution response, which is (i) in response to determining that the requesting communication device is not attached to a second MLD but carries the MAC address of the associated STA, or (ii) in response to determining that the requesting communication device is attached to a second MLD but carries the MAC address of the first MLD to which the associated STA is attached. Radio transmitter 402 can, for example, transmit the second data frame to the requesting communication device.

[0086] Figure 5A flowchart 500 illustrating a communication method according to the present disclosure is shown. In step 502, a first data frame carrying an address resolution request is received from the requesting communication device, the address resolution request carrying the IP address of a first MLD. In step 504, a step is performed to determine whether the requesting communication device is attached to a second MLD. In step 506, a second data frame carrying an address resolution response is performed. This address resolution response may be (i) in response to determining that the requesting communication device is not attached to the second MLD but carries the MAC address of a communication device among a plurality of communication devices attached to the first MLD, or (ii) in response to determining that the requesting communication device is attached to the second MLD but carries the MAC address of the first MLD.

[0087] In the following paragraphs, the first embodiment of this disclosure is explained with reference to multi-link address resolution in AP MLD, non-AP MLD and / or non-MLD STA, wherein the AP MLD and non-AP MLD use the same MAC SAP for MLD and non-MLD connections.

[0088] In a first embodiment of this disclosure, the MLD uses the same MAC SAP for connecting both the MLD and non-MLD. Figure 6A and Figure 6B The diagrams 600 and 620 illustrate an example configuration of an AP MLD 602 ​​and a non-AP MLD 622 for multi-link address resolution according to a first embodiment of this disclosure, and the communication between their respective network interface layers and their respective Internet layers 604 and 624. Each AP MLD 602 ​​and non-AP MLD 622 maintains a single IP address 606 and 626 mapped to MLD MAC addresses 608 and 628. For example, all ARP and ND messages received by AP MLD 602 ​​and non-AP MLD 622 from links 610 and 630 via conventional ARP message paths or MLD ARP message paths are routed via the MAC SAP612 and 632 of MLD 602 ​​and 622, respectively. As a result, MLD 602 ​​and 622 will always return their respective MLD MAC addresses 608 and 628 as their hardware / L2 MAC addresses.

[0089] Figure 7A flowchart 700 illustrating communication between an AP MLD 702 and a non-AP MLD 712 for multi-link address resolution according to a first embodiment of the present disclosure is shown. The AP MLD 702 is associated with two APs (AP1, AP2 704) operating on the 5 GHz and 6 GHz frequency bands, respectively. The AP MLD 702 is associated with a non-AP MLD1 712, which is associated with two STAs (STA1, STA2 714) operating on the 5 GHz and 6 GHz frequency bands, respectively.

[0090] This example illustrates a non-AP MLD (e.g., non-AP MLD1 712) resolving the IP address of an associated AP MLD (e.g., AP MLD 702). STA2 714 of non-AP MLD1 712 can initiate an ARP query by generating a first data frame 722 carrying a broadcast address in its DA field 726 and an Address Resolution Request (ARP Request) 724 and sending it to AP MLD 702 on a 6GHz link (band). The broadcast address in the DA field 726 indicates that the first data frame 722 is intended to be broadcast to all STAs and non-AP MLDs associated with AP MLD 702. The ARP Request 724 carries the IP address of AP MLD 702 in its Destination IP field 728 to indicate that non-AP MLD1 712 is attempting to resolve that IP address to obtain the corresponding MAC address of AP MLD 702.

[0091] Next, AP2 704, which receives the first data frame 722 (where the DA field is set to the broadcast address) on the 6GHz link, forwards the first data frame 722' carrying the ARP request 724' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS) including non-AP MLD1 712. AP2 704 sets the SA field 727' to the MAC address of non-AP MLD1 712 to indicate that the original sender of the first data frame 722' is non-AP MLD1 712. Since the destination IP address carried in the destination IP field 728' of the ARP request 724' received by STA2 714 does not match the IP address of its MLD, STA2 714 either ignores the ARP request 724' or rejects it as a loopback frame.

[0092] On the other hand, since the destination IP address carried in the destination IP field 728 of the ARP request 724 received by AP2 704 matches the IP address of its AP MLD, AP2 704 can generate a second data frame 732 carrying an address resolution response (ARP reply) 734 and send it to non-AP MLD1 712 via the 6GHz link. AP MLD 702 provides its AP MLD's MAC address in the source hardware field 736 of the ARP reply 734. The ARP reply 734 also carries the MAC address and IP address of non-AP MLD1 in the destination hardware field 738 and destination IP field 739, respectively, to indicate that non-AP MLD1 712 is the target recipient of the ARP reply 734.

[0093] Since the destination IP address carried in the destination IP field 739 of the ARP reply 734 received by STA2 714 matches the IP address of its MLD, STA2 714 can process the second data frame 732 and update its ARP cache to map the IP address of AP MLD (AP-MLD-IP) in the source IP field 737 to the MAC address of AP MLD (AP-MLD-M) and the source hardware field 736 of the ARP reply 734. As a result, the ARP query is resolved.

[0094] Subsequently, the non-AP MLD 712 can send a subsequent data frame (IP packet) 742 to the AP MLD 702. The IP packet destined for AP-MLD-IP will be addressed to the IP layer AP-MLD-M, but because the non-AP MLD 712 is associated with the AP-MLD, it knows all the AP MAC addresses of the AP MLD and therefore sets the RA field 744 of the data frame 742 carrying the IP packet to the MAC address of one of the APs associated with AP MLD 702 (in this case, AP2 704). As we can see, address resolution works perfectly in this scenario.

[0095] Figure 8A flowchart illustrating communication 800 between two non-AP MLDs 812, 822 via AP MLD 802 for multi-link address resolution according to a first embodiment of the present disclosure is shown. AP MLD 802 is associated with two APs (AP1, AP2 804) operating on the 5 GHz and 6 GHz frequency bands, respectively. AP MLD 802 is associated with non-AP MLD1 814 and non-AP MLD2 816. Non-AP MLD1 814 is associated with two STAs (STA1, STA2 814) operating on the 5 GHz and 6 GHz frequency bands, respectively; and non-AP MLD2 822 is associated with two STAs (STA3, STA4 824) operating on the 5 GHz and 6 GHz frequency bands, respectively.

[0096] This example illustrates a non-APMLD (e.g., non-AP MLD1 812) resolving the IP address of another non-AP MLD (e.g., non-AP MLD2 822). STA2 814 of non-AP MLD1 812 can initiate an ARP query by generating a first data frame 832 carrying a broadcast address in its DA field 835 and an Address Resolution Request (ARP Request) 834 and sending it to APMLD 802 on a 6GHz link (band). The broadcast address in the DA field 835 indicates that the first data frame 832 is being broadcast to all associated STAs and non-AP MLDs. The ARP Request 834 carries the IP address of non-AP MLD2 812 in the Destination IP field 839 to indicate that non-AP MLD1 812 is attempting to resolve that IP address to obtain the corresponding MAC address of AP MLD2 822.

[0097] Next, AP2 804, which receives the first data frame 832 on the 6GHz link via AP MLD 802, forwards the first data frame 832' carrying ARP request 834' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS), which includes non-AP MLD1 812 and non-AP MLD2 822. The SA field 835' carries the MAC address of non-AP MLD1 812 to indicate that the original sender of the first data frame 832' is non-AP MLD1 812. Because the destination IP address carried in the destination IP field 839' of the ARP request 834' received by STA2 814 and AP2 804 does not match the IP address of their respective MLDs, STA2 814 and AP2 804 either ignore the ARP request 834' or reject it as a loopback frame.

[0098] On the other hand, since the destination IP address carried in the destination IP field 838' of the ARP request 834' received by STA4 824 matches the IP address (STA-MLD2-IP) of its non-AP MLD2, STA4 824 can generate a second data frame 842 carrying an address resolution response (ARP reply) 844 and send it to AP MLD 802 via the 6GHz link. Non-AP MLD2 822 provides its non-AP MLD2 MAC address (STA-MLD2-M) in the source hardware field 846 of the ARP reply 844. The ARP reply 844 also carries the MAC address and IP address (STA-MLD1-M and STA-MLD1-IP) of non-AP MLD1 812 in the destination hardware field 848 and destination IP field 849, respectively, to indicate that non-AP MLD1 812 is the target recipient of the ARP reply 844.

[0099] The AP MLD 802 that receives the second data frame 842 recognizes that the ARP reply 844 carried in the second data frame 842 is directed to the associated non-AP MLD (in this case, non-APMLD1 based on the MAC address (STA-MLD1-M) in the DA field), and forwards the second data frame 842' carrying the ARP reply 844' to non-APMLD1 812 via any of the affiliated APs (in this case, forwarded to STA2 814 via AP2 804 via the 6GHz link).

[0100] Since the destination IP address carried in the destination IP field 849' of the ARP reply 844' received by STA2 814 matches the IP address (STA-MLD1-IP) of its MLD, the non-AP MLD1 812 can then process the second data frame 842' and update its ARP cache to map the IP address (STA-MLD2-IP) of the non-AP MLD2 in the source IP field 847' to the MAC address (STA-MLD2-M) of the non-AP MLD2 in the source hardware field 846' of the ARP reply 844'. As a result, the ARP query is resolved.

[0101] Subsequently, the non-AP MLD1 812 can send subsequent data frames (IP packets) 852 to the non-AP-MLD2 822 via AP MLD 802. IP packets destined for STA-MLD2-IP will be addressed to the IP layer STA-MLD2-M, and the DA field 855 of the subsequent data frame 852 will be set to the MLD MAC address (STA-MLD2-M) of the non-AP MLD2 822 at the MLD level based on the record in its ARP cache.

[0102] The AP MLD 802, receiving IP packet 852, recognizes that IP packet 852 is directed to the associated non-AP MLD (in this case, non-AP MLD2 based on DA field 855 (STA-MLD2-M)) and forwards IP packet 852' to non-AP MLD2 822 via any of the affiliated APs (in this case, forwarded to STA4 824 via AP2 804 through the 6GHz link). Note that since non-AP MLD2 822 is associated with AP MLD 802, AP MLD 802 knows the L2 MAC address of STA4 824. When forwarding IP packet 852' to STA4 824, AP MLD 802 is able to translate the MLD address (STA-MLD2-M) of non-AP MLD2 into the MAC address (STA4-M) of STA4 in RA field 853'. In this way, IP packet 852' will be correctly received by STA4 824, and frames sent via AP-MLD 802 will be fine.

[0103] However, for ARP performed under the first embodiment of this disclosure, frames sent by a non-AP MLD (e.g., non-AP MLD1) to another non-AP MLD (e.g., non-AP MLD2) on a direct link (not via AP-MLD 802) will fail because the RA field is set to the MLD MAC address instead of the STA's L2 MAC address. Return to Figure 8 In the example shown, after the ARP query has been resolved, non-AP MLD1 812 might want to send a common action frame (Access Network Query Protocol (ANQP) request frame) 862 to non-AP ML2 822 on the direct link. Note that non-AP MLD1 812 is not associated with non-AP MLD2 822, therefore non-AP MLD1 812 may not know the L2 MAC address of STA4 824, and the RA field 863 of the ANQP request frame 862 is set to the MLD MAC address of non-AP MLD2 (STA-MLD2-M), instead of the L2 MAC address of STA4. This will cause STA4 824 to drop or ignore the ANQP request frame 862 sent on the direct link.

[0104] Figure 9A flowchart 900 illustrates communication via AP MLD 902 between a non-AP MLD 922 and a conventional STA 912 for multi-link address resolution according to a first embodiment of the present disclosure. AP MLD 902 is associated with two APs (AP1, AP2 904) operating in the 5 GHz and 6 GHz bands, respectively. AP MLD 902 is associated with STA 912 and the non-AP MLD 922. The non-AP MLD 922 is associated with two STAs (STA3, STA4 924) operating in the 5 GHz and 6 GHz bands, respectively. STA 912 operates in the 6 GHz band.

[0105] This example illustrates a conventional STA (e.g., STA5 912) resolving the IP address of a non-AP MLD (e.g., non-AP MLD2 922). STA5 912 can initiate an ARP query by generating a first data frame 932 carrying a broadcast address in its DA field 935 and an Address Resolution Request (ARP Request) 934 and sending it to AP MLD 902 on a 6GHz link (band). The broadcast address in the DA field 935 indicates that the first data frame 932 is being broadcast to all associated STAs and non-AP MLDs. The ARP Request 934 carries the IP address of non-AP MLD2 924 in its Destination IP field 939 to indicate that non-AP STA5 912 is attempting to resolve that IP address to obtain the corresponding MAC address of non-AP MLD2 924.

[0106] Next, AP2 904, which receives the first data frame 932 on the 6GHz link via AP MLD 902, forwards the first data frame 932' carrying ARP request 934' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS), including STA5 912 and non-AP MLD2 924. The SA field 935' carries the MAC address of STA5 912 to indicate that the original sender of the first data frame 932' is STA5 912. Because the destination IP address carried in the destination IP field 939' of the ARP request 934' received by STA5 912 and AP2 904 does not match their respective L2 and MLD MAC IP addresses, STA5 912 and AP2 904 either ignore the ARP request 934' or reject it as a loopback frame.

[0107] On the other hand, since the destination IP address carried in the destination IP field 939' of the ARP request 934' received by STA4 924 matches its non-AP MLD2 IP address (STA-MLD2-IP), STA4 924 can generate a second data frame 942 carrying an address resolution response (ARP reply) 944 and send it to AP MLD 902 via the 6GHz link. The non-AP MLD2 924 provides its non-AP MLD2 MAC address (STA-MLD2-M) in the source hardware field 946 of the ARP reply 944. The ARP reply 944 also carries the MAC address and IP address (STA5-M and STA5-IP) of STA5 912 in the destination hardware field 948 and destination IP field 949 respectively, indicating that STA5 912 is the target recipient of the ARP reply 944.

[0108] The AP MLD 902, which receives the second data frame 942, recognizes that the ARP reply 944 carried in the second data frame 942 is directed to the associated STA (in this case, STA5 912 based on the MAC address (STA5-M) in the DA field 945), and forwards the second data frame 942' carrying the ARP reply 944' to STA5 912 in the 6GHz band via the affiliated AP (in this case, AP2 904 via the 6GHz link).

[0109] Since the destination IP address carried in the destination IP field 949' of the ARP reply 944' received by STA5 912 matches its IP address (STA5-IP), STA5 912 can then process the second data frame 942' and update its ARP cache to map the non-AP MLD IP address (STA-MLD2-IP) in the source IP field 947' to the AP MLD MAC address (STA-MLD2-M) in the source hardware field 946' of the ARP reply 944'. As a result, the ARP query is resolved.

[0110] Subsequently, STA5 912 can send subsequent data frames (IP packets) 952 to non-AP-MLD2 922 via AP MLD 902. IP packets destined for STA-MLD2-IP will be addressed to the IP layer STA-MLD2-M, where the DA field 955 of IP packet 962 is set to the MLD MAC address of non-AP MLD2 922 (STA-MLD2-M).

[0111] The AP MLD 902 receiving IP packet 952 recognizes that IP packet 952 is directed to the associated non-AP MLD (in this case, non-AP MLD2 922 based on the IP address (STA-MLD2-IP) in the destination IP field 957), and forwards IP packet 952' to the target hardware, i.e., non-AP MLD2 922 (in this case, forwarded to STA4 924 via AP2904 through the 6GHz link), through any of the affiliated APs. Note that since non-AP MLD2 922 is associated with AP MLD 902, AP MLD 902 knows the L2 MAC address of STA4 924. When forwarding IP packet 952' to STA4 924, AP MLD 902 is able to translate the MLD address (STA-MLD2-M) of non-AP MLD2 into the MAC address (STA4-M) of STA4 in the RA field 953'. In this way, IP packet 952' will be correctly received by STA4 924, and frames sent via AP-MLD 902 will be fine.

[0112] However, for ARP performed under the first embodiment of this disclosure, frames sent by a conventional STA (e.g., STA5 912) on a direct link (not via AP-MLD 902) to a non-AP MLD (e.g., non-AP MLD2 922) will fail because the RA field is set to the MLD MAC address instead of the STA's L2 MAC address. Return to Figure 9 In the example shown, after the ARP query has been resolved, STA5 912 might want to send a Common Action Frame (ANQP Request Frame) 962 to the non-AP ML2 922 on the direct link. Note that STA5 912 is not associated with the non-AP MLD2 922, therefore STA5 912 may not know the L2 MAC address of STA4 924. The RA field 963 of the ANQP Request Frame 962 is set to the MLD MAC address of the non-AP MLD2 (STA-MLD2-M), instead of the L2 MAC address of STA4. This will cause the ANQP Request Frame 962 sent on the direct link to be dropped or ignored by STA4 924.

[0113] Figure 10A flowchart 1000 illustrating communication between AP MLD 1002, a non-AP MLD 1022, and a conventional STA 1012 for multi-link address resolution according to a first embodiment of the present disclosure is shown. AP MLD 1002 is associated with two APs (AP1, AP2 1004) operating on the 5 GHz and 6 GHz frequency bands, respectively. AP MLD 1002 is associated with non-AP MLD2 1012 and STA5 1022. Non-AP MLD2 1012 is associated with two STAs (STA3, STA4 1014) operating on the 5 GHz and 6 GHz frequency bands, respectively. STA5 1022 operates on the 6 GHz frequency band.

[0114] This example illustrates a non-AP MLD (e.g., non-AP MLD2 1012) resolving the IP address of a traditional STA (e.g., STA5 1022). STA4 of non-AP MLD2 1012 can initiate an ARP query by generating a first data frame 1032 carrying a broadcast address in its DA field 1035 and an Address Resolution Request (ARP Request) 1034 and sending it to AP MLD1002 on a 6GHz link (band). The broadcast address in the DA field 1035 indicates that the first data frame 1032 is being broadcast to all associated STAs and non-AP MLDs. The ARP Request 1034 carries the IP address of STA5 1022 in the Destination IP field 1039 to indicate that non-AP MLD2 1012 is attempting to resolve the IP address to obtain the corresponding MAC address of STA5 1022.

[0115] Next, AP21004, which receives the first data frame 1032 on the 6GHz link, forwards the first data frame 1032' carrying ARP request 1034' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS), including non-AP MLD21012 and STA51022. The SA field 1035' carries the MAC address of non-AP MLD21012 to indicate that the original sender of the first data frame 1032' is non-AP MLD21012. Because the destination IP address carried in the destination IP field 1039' of the ARP request 1034' received by STA41014 and AP21004 does not match their respective L2 and MLD MAC IP addresses, STA41014 and AP21004 either ignore the ARP request 1034' or reject it as a loopback frame.

[0116] On the other hand, since the destination IP address carried in the destination IP field 1039' of the ARP request 1034' received by STA5 1022 matches its IP address (STA5-IP), STA5 1022 can generate a second data frame 1042 carrying an address resolution response (ARP reply) 1044 and send it to AP MLD 1002 via the 6GHz link. STA5 1022 provides its L2 MAC address (STA5-M) in the source hardware field 1046 of the ARP reply 1044. The ARP reply 1044 also carries the MAC address and IP address (STA-MLD2-M and STA-MLD2-IP) of the non-AP MLD2 1012 in the destination hardware field 1048 and destination IP field 1049, respectively, to indicate that the non-AP MLD2 1012 is the target recipient of the ARP reply 1044.

[0117] AP MLD 1002, which receives the second data frame 1042, recognizes that the ARP reply 1044 carried in the second data frame 1042 is directed to the associated STA (in this case, the non-AP MLD2 1012 based on the MAC address (STA-MLD2-M) in the DA field), and forwards the second data frame 1042' carrying the ARP reply 1044' to the non-AP MLD2 1012 via any of the affiliated APs (in this case, via the 6GHz link through AP2 1004 to STA4 1014).

[0118] Since the destination IP address carried in the destination IP field 1049' of the ARP reply 1044' received by STA4 1014 matches its IP address (STA-MLD2-IP), STA4 1014 can then process the second data frame 1042' and update its ARP cache to map the IP address of STA5 (STA5-IP) in the source IP field 1047' to the MAC address of STA5 (STA5-M) in the source hardware field 1046' of the ARP reply 1044'. As a result, the ARP query is resolved.

[0119] Subsequently, the non-AP MLD2 1012 can initiate Tunnel Direct Link Establishment (TDLS) discovery by sending a follow-up data frame 1052 carrying a TDLS discovery request 1054 to STA51022 via AP MLD 1002 operating on the 6GHz link. The TDLS discovery request includes a TDLS initiator field set to the MAC address of the non-AP MLD2 1012 and a TDLS responder field 1059 set to the MAC address of STA5 1022, indicating that the non-AP MLD2 1012 (initiator) is attempting to establish a direct link with STA51022 (responder).

[0120] The AP MLD 1022, receiving subsequent data frame 1052, recognizes that the TDLS discovery request 1054 carried in data frame 1052 is directed to the associated STA (in this case, STA5 1012 based on the MAC address (STA5-M) in the DA field), and forwards data frame 1052' to STA5 1022. Note that since STA5 1022 is associated with AP MLD 1022, AP MLD 902 knows the L2 MAC address of STA5 1024, and when forwarding data frame 1052 to STA5 1022, AP MLD 902 sets the MAC address (STA5-M) of STA5 in the RA field 1053'. Thus, the data frame will be correctly received by STA5 1022.

[0121] STA5 1022, which receives TDLS discovery request 1054', can send TDLS discovery response action frame 1062 back to STA4 1014 on the direct link (i.e., the operational link of STA5 (link 2 or 6GHz band)). However, similar to Figure 9 In the example shown, since STA5 1022 is not associated with the non-AP MLD2 1012, STA5 1022 may not know the L2 MAC address of STA4 1014. The RA field 1063 of the TDLS discovery response action frame 1062 is set to the MLD MAC address of the non-AP MLD2 (STA-MLD2-M) based on the TDLS initiator field in the TDLS discovery request 1054', instead of the L2 MAC address of STA4. This will cause the TDLS discovery response action frame 1062 sent on the direct link to be dropped or ignored by STA4 1014.

[0122] Therefore, according to this disclosure, in order to correctly receive frames transmitted by another non-AP MLD or a traditional STA on a direct link, in addition to the usual frame filtering standards, the non-AP MLD should be configured to also accept specific frames whose RA field is set to their MLD MAC address. Specifically, to avoid unnecessary checks, only the RA field of certain frames is checked against the MLD MAC address, such as (i) data frames where the frame control fields “To DS” and “From DS” are set to 0 (for peer-to-peer transmission settings) and (ii) common action frames for peer discovery, such as TLDS discovery response frames and group address request / response frames (for ANQP request / response).

[0123] However, this violates the 802.11be protocol, which stipulates that the value of the Address 1 (RA) field in the MAC header of a separately addressed frame sent via over-the-air download should be the MAC address of the receiving STA attached to the MLD corresponding to that link (instead of the MLD's MLD MAC address).

[0124] Therefore, there is a need for communication devices and methods that provide feasible technical solutions for multilink address resolution to address one or more of the above challenges, such that multilink address resolution can result in frames transmitted on a direct link being correctly received by another non-AP MLD or conventional STA according to the 802.11be protocol regarding the RA / TA field settings.

[0125] According to a second embodiment of this disclosure, the IP address of the MLD is dynamically mapped to either the MLD's MAC address or its L2 MAC address. A determination can be performed to determine which MAC address is returned as the MLD's hardware MAC address in response to an address resolution request (ARP request or neighbor request message). This depends on whether the requesting STA, which sent the address resolution request to resolve the IP address of another MLD or STA, is an MLD or a non-MLD.

[0126] If the requesting STA is determined to be an MLD, the MLD MAC address is returned as the MLD's hardware MAC address. However, if the requesting STA is determined to be a non-MLD (EHT or traditional STA), the MAC address of the affiliated AP / STA operating on the link in which the address resolution request was received is returned as the MLD's hardware MAC address. Therefore, from the non-MLD's perspective, the MLD is identified by the MAC address of the affiliated AP / STA operating on the same link in which the non-MLD operates. However, if the non-MLD happens to be operating on a link not among the links established by the MLD, the MLD can be identified by its MLD MAC address.

[0127] One possible solution to achieve the above is to use different MAC SAPs for MLD and non-MLD / legacy connections. In the following paragraphs, a second embodiment of this disclosure is explained with reference to multi-link address resolution in AP MLD, non-AP MLD, and / or non-MLD STA, wherein AP MLD and non-AP MLD use different MAC SAPs for MLD and non-MLD / legacy connections.

[0128] Frames sent by MLD can carry an "ML indication" to indicate that they were sent by (or originated from) MLD. The "ML indication" can be carried in all frames sent by MLD, or it can be carried in frames sent / relayed by AP MLD.

[0129] According to a second embodiment of this disclosure, an MLD address lookup mechanism is proposed to perform MLD MAC address to L2 MAC address resolution, which will be relevant to... Figure 18 The following paragraphs will provide an explanation.

[0130] In addition, the AP MLD can provide a proxy ARP feature, which dynamically maps the associated non-AP MLD IP address to either the non-AP MLD's MLD MAC address or the non-AP MLD's L2 MAC address. The AP MLD can perform determination on behalf of the non-AP MLD to determine which MAC address is returned as the non-AP MLD's hardware MAC address in response to an address resolution request (ARP request or neighbor request message). This depends on whether the requesting STA, whether it is an MLD or a non-MLD, is sending the address resolution request to resolve the IP address of the non-AP MLD or the STA.

[0131] If the requesting STA is determined to be an MLD, the MLD MAC address of the non-AP MLD is returned as the MLD's hardware MAC address. However, if the requesting STA is determined to be a non-MLD (EHT or a traditional STA), the MAC address of the associated STA of the MLD operating on the link where the address resolution request was received is returned as the MLD's hardware MAC address. However, if the non-MLD happens to be operating on a link not in any of the established links of the associated non-AP MLD, the AP MLD may return the non-AP MLD's MLD MAC address as its hardware MAC address.

[0132] According to the second embodiment, when a unicast data frame sent by an associated non-AP MLD is forwarded to an associated non-MLD STA (e.g., a traditional STA), the AP MLD sets the SA field of the forwarded data frame to the MAC address of the STA of the non-AP MLD corresponding to the link in which the frame was received by the AP MLD. Similarly, when a unicast data frame sent by an associated non-MLD STA (e.g., a traditional STA) is forwarded to an associated non-AP MLD, the AP MLD forwards the frame on the same link in which it was received, provided that the non-AP MLD has an affiliated AP operating on the link (i.e., link crossing is not allowed).

[0133] In TDLS frames sent from a non-AP MLD to a non-MLD STA (e.g., a traditional STA), relevant address fields such as the TDLS initiating STA and the TDLS responding STA are set to the STA MAC address of the non-AP MLD corresponding to the transmission link (instead of the MLD MAC address).

[0134] Figure 11A and Figure 11BThe diagrams 1100 and 1150 illustrate an example configuration of an AP MLD 1102 and a non-AP MLD 1152 for multi-link address resolution according to a second embodiment of the present disclosure, and the communication between the respective network interface layers and their respective Internet layers 1104 and 1154. Each AP MLD 1102 and non-AP MLD 1152 maintains a single IP address 1106 and 1156 mapped to MLD MAC addresses 1108 and 1158, and the MLD's MAC SAP (e.g., MAC-SAP-1 1112, 1162) and the AP / STA MAC SAP of each of the subordinate APs / STAs within the MLD (e.g., MAC-SAP-2 1114, 1154 for AP1 / STA1 and MAC-SAP-3 1116, 1156 for AP2 / STA2).

[0135] AP MLD 1100 and non-AP MLD 1150 use different MAC SAPs for MLD and non-MLD (including legacy STA) connections. The MLD's IP address is dynamically mapped to MLD MAC addresses 1108, 1158 or STA MAC addresses 1118, 1120, 1168, 1170. Traffic from MLD to DS / from DS to MLD (including ARP and ND messages) is routed via MLD MAC SAPs 1112, 1162, as indicated by lines 1122, 1172; while traffic from non-MLD to DS / from DS to non-MLD (including ARP and ND messages) is routed via STA MAC SAPs 1114, 1116, 1154, 1156, as indicated by lines 1124, 1174. ARP / ND 1105, 1155 return the MAC address of the corresponding MAC SAP through which ARP / ND requests are received. In other words, if an ARP / ND request is received from a non-MLD source, the traffic is routed via the STAMAC SAP and the STAMAC address is returned; while if an ARP / ND request is received from an MLD source, the traffic is routed via the MLD MAC SAP and the MLD MAC address is returned.

[0136] Furthermore, it is possible to assign multiple IP addresses to a device, and there is a one-to-one mapping between the IP address and the MAC address corresponding to each MAC SAP; for example, one IP address corresponding to the MLD MAC address; and one IP address corresponding to each of the AP / STA MAC addresses.

[0137] Figure 12An example format of a data frame 1200 according to a second embodiment of the present disclosure is shown. The data frame 1200 may include a frame control field, a duration field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, a quality of service (QoS) control field, an HT field, a payload field, and a frame check sequence (FCS). The frame control field 1202, duration field, address 1 field, address 2 field, address 3 field, sequence control, QoS control field, and HT control field may be grouped into a MAC header. The frame control field 1202 includes a protocol version subfield 1204, a type subfield, a subtype subfield, a To DS subfield, a From DS subfield, a More Fragments subfield, a Retry subfield, a Power Management subfield, a More Data subfield, a Protected Frame subfield, and a +HTC subfield.

[0138] When the Protocol Version subfield 1204 in the Frame Control field 1202 of data frame 1200 is set to a value other than "b00", it acts as an "ML Indicator" identifying the sending / originating device as an MLD. The receiving STA / AP or the STA / AP of the receiving MLD uses the presence of the "ML Indicator" to determine whether the sending / originating device is an MLD, and thus to determine the MAC SAP to which the received data frame is forwarded. Specifically, data frames received by the receiving MLD carrying this "ML Indicator" are forwarded to the MLD MACSAP, while all other data frames are forwarded to the STA / AP MAC SAP. The receiving MLD's ARP / ND returns the MAC address corresponding to the MAC SAP through which it received the ARP / ND request as the receiving MLD's hardware address. Advantageously, the MLD's hardware MAC address is correctly mapped based on the ML Indicator identifying the type of requesting STA (MLD or non-MLD).

[0139] For example, based on capability exchange during the association process, the AP knows the device type of all associated devices. Even without an "ML instruction," the AP can determine the MAC SAP based on the TA field. Data frames from traditional STAs go to the AP MAC SAP, while data frames from non-AP MLDs go to the MLD MAC SAP.

[0140] Figure 13A flowchart illustrating communication between AP MLD1302 and non-MLD STA1312 for multi-link address resolution according to a second embodiment of the present disclosure is shown. AP MLD1302 is associated with two APs (AP1, AP2 1304) operating on the 5 GHz and 6 GHz bands, respectively. AP MLD1302 is associated with STA5 1312 on the 6 GHz band.

[0141] This example illustrates a traditional STA (e.g., STA5 1312) resolving the IPv4 address of an associated AP MLD (e.g., AP MLD 1302). STA5 1312 can initiate an ARP query by generating a first data frame 1322 carrying a broadcast address in its DA field 1325 and an Address Resolution Request (ARP Request) 1324 and sending it to AP MLD 1302 on a 6GHz link (band). The broadcast address in the DA field 1325 indicates that the first data frame 1322 is being broadcast to all associated STAs and non-AP MLDs. The ARP Request 1324 carries the IP address of AP MLD 1302 (AP-MLD-IP) in the Destination IP field 1329 to indicate that STA5 1312 is attempting to resolve the IP address to obtain the corresponding MAC address of AP-MLD 1302.

[0142] Next, AP21304, which receives the first data frame 1322 on the 6GHz link via AP MLD 1302, can forward the first data frame 1322' carrying ARP request 1324' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS) including STA5 1312. The SA field 1325' carries the MAC address of STA5 to indicate that the original sender of the first data frame 1322' is STA5. Because the destination IP address carried in the destination IP field 1329' of the ARP request 1324' received by STA5 1312 does not match its IP address, STA5 1312 either ignores the ARP request 1324' or rejects it as a loopback frame.

[0143] On the other hand, since the destination IP address carried in the destination IP field 1329 of the ARP request 1324 received by AP2 1304 matches the IP address of its AP MLD, AP2 1304 can identify the originating device as STA5 1312 based on the SA field 1325' and determine the device type of the requesting device STA5 1312. In this case, AP2 1304 can determine that STA5 is not an MLD, and based on this, ARP request 1324 is forwarded to AP2 MAC SAP (instead of MLD MAC SAP).

[0144] The second data frame 1332, carrying an Address Resolution Response (ARP Reply) 1334, can be generated by AP MLD 1302 and passed down via AP2's MAC SAP to be sent from AP2 1304 to STA5 1312 via a 6GHz link. ARP Reply 1334 carries AP2's MAC address (AP2-M) in the Source Hardware Field 1336, AP MLD's IP address in the Source IP Field 1337, STA5's MAC address in the Destination Hardware Field 1338, and STA5's IP address in the Destination IP Field 1339, indicating that STA5 1312 is the target receiver of ARP Reply 1334.

[0145] Since the destination IP address carried in the destination IP field 1339 of the ARP reply 1334 received by STA5 1312 matches its IP address, STA5 1312 can process the second data frame 1332 and update its ARP cache to map the IP address of AP MLD (AP-MLD-IP) in the source IP field 1337 to the MAC address of AP2 (AP2-M) in the source hardware field 1336 of the ARP reply 1334. As a result, the ARP query is resolved.

[0146] Subsequently, STA5 1312 can send the next data frame 1342 to AP2 1304 via AP2 MAC-SAP. The data frame 1342 destined for AP-MLD will be addressed to the IP layer AP2, where the RA field 1353 of data frame 1342 is set to the MAC address of AP2 (AP2-M).

[0147] Figure 14 A flowchart 1400 is shown illustrating a first example of communication via AP MLD 1402 for multi-link address resolution between a non-AP MLD 1422 and a non-MLD STA1412 according to a second embodiment of the present disclosure.

[0148] In this first example, a conventional STA (e.g., STA5 1412) is shown resolving the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 1422) using a public link (e.g., Link 2 or the 6GHz band). STA5 1412 can initiate an ARP query by generating a first data frame 1432 carrying a broadcast address and an Address Resolution Request (ARP Request) 1434 in its DA field 1435 and sending it to AP MLD 1402 on the 6GHz link (band). The broadcast address in the DA field 1435 indicates that the first data frame 1432 is being broadcast to all associated APs and AP MLDs. The ARP Request 1434 carries the IP address of non-AP MLD2 1422 in the Destination IP field 1439 to indicate that STA5 1412 is attempting to resolve that IP address to obtain the corresponding MAC address of non-AP MLD2 1422.

[0149] Next, AP21404, which receives the first data frame 1432 on the 6GHz link via AP MLD 1402, can forward the first data frame 1432' carrying ARP request 1434' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS), including STA5 1412 and non-AP MLD2 1422. The SA field 1435' carries the MAC address of STA5 1412 to indicate that the original sender of the first data frame 1434' is STA5 1412. Because the destination IP address carried in the destination IP field 1439' of the ARP request 1434' received by STA5 1412 and AP2 1404 does not match their respective L2 and MLD MAC IP addresses, STA5 1412 and AP2 1404 either ignore the ARP request 1434' or reject it as a loopback frame.

[0150] STA4 1424 can identify that ARP request 1434' originates from STA5 1412 based on SA field 1435', and determine that the requesting device STA5 1412 is a non-MLD due to the lack of "ML indication" in the first data frame 1432'. Based on this, ARP request 1434' is forwarded to the ARP / IP layer via STA4 MAC SAP. Non-AP MLD2 1422 can also record Link 2 (6GHz band) as the operational link of STA5.

[0151] Because the destination IP address carried in the destination IP field 1439' of ARP request 1434' matches the IP address (STA-MLD2-IP) of a non-AP MLD2, AP MLD2 can use its STA MAC SAP to generate a second data frame 1442 carrying an address resolution response (ARP reply) 1444, and send data frame 1442 to AP2 1404 via STA4. The ARP reply 1444 carried in data frame 1442 carries the MAC address of STA4 (STA4-M) in the source hardware field 1446, the MAC address of STA5 in the destination hardware field 1448, and the IP address of STA5 in the destination IP field 1449, indicating that STA5 1412 is the target recipient of ARP reply 1444.

[0152] The AP MLD 1402, receiving the second data frame 1442, identifies that the ARP reply 1444 carried in the second data frame 1442 is directed to STA5 based on the MAC address (STA5-M) in the target hardware field 1448. It then forwards the second data frame 1442' carrying the ARP reply 1444' to STA5 1412 via AP2 1404 operating on the operational link (link 2) of STA5. Note that the SA field of the second data frame 1442' is set to the MAC address of STA4 (instead of the MLD MAC address of a non-AP MLD) to identify the original sending STA of the second data frame 1442 as STA4 1424.

[0153] STA5 1412, which receives the second data frame 1442, can process the second data frame 1442 and update its ARP cache to map the IP address of the non-AP MLD (STA-MLD2-IP) in the source IP field 1447' to the MAC address of STA4 (STA4-M) in the source hardware field 1446' of the ARP reply 1444'. As a result, the ARP query is resolved.

[0154] Subsequently, STA4 1424, a non-AP MLD2 1422, can initiate TDLS discovery by sending a follow-up data frame 1452 carrying a TDLS discovery request 1454 to STA5 1412. STA4 1424 is used as the TDLS initiator because STA4 1424 now knows that the peer device is a non-MLD STA, namely STA5 1412, which is operating on link 2. The TDLS discovery request 1454 includes a TDLS initiator field set to the MAC address of STA4 and a TDLS responder field 1459 set to the MAC address of STA5 1412.

[0155] AP MLD 1402, receiving subsequent data frame 1452, identifies the TDLS discovery request 1454 carried in data frame 1452 as being directed to STA5 1412 based on the MAC address (STA5-M) of STA5 in the TDLS responder field 1459. It then forwards data frame 1452', which carries the MAC address (STA4-M) of STA4 in the SA field 1455', and the TDLS discovery request 1454' received from non-AP MLD2 1422, to STA5 1412. When forwarding data frame 1452' to STA5 1412, AP MLD 1402 sets the MAC address (STA5-M) of STA5 in the RA field 1453'. Therefore, the data frame will be correctly received by STA5 1412.

[0156] STA5 1412, which receives TDLS discovery request 1454', can send TDLS discovery response action frame 1462 back to STA4 1426 on the direct link (i.e., STA5's operational link (link 2)). STA5 1412 is able to set the RA field 1463 of TDLS discovery response action frame 1462 to the MAC address of STA4 (STA4-M) based on the mapping stored in its ARP cache. This results in frames such as TDLS discovery response action frame 1462 sent by STA5 1412 on the direct link to non-AP MLD 1422 being correctly received via STA4 1424.

[0157] This resolves the problem described in the first embodiment of this disclosure where frames transmitted on a direct link between a traditional STA and a non-AP MLD fail to be received correctly. Because the SA field and the TDLS initiator field in the link identifier element of a TDLS discovery request frame relayed by the AP are both set to the STA MAC address, no confusion occurs at the receiving peer STA.

[0158] When forwarding a group-addressed data frame received from an associated non-MLD (e.g., 1432), the AP MLD will forward the frame on the same link in which it was received (e.g., on a 6GHz link) as long as the associated non-AP MLD is operating on the link. If an associated non-AP MLD is operating in power-saving mode on that link and is actively operating on another link (e.g., a 5GHz link), the AP will buffer such non-AP MLD data frames on the 6GHz link and notify the non-AP MLD of the buffered frame on the 5GHz link, for example, using the TIM element in a DTIM beacon frame. This is to ensure that data frames are forwarded via the correct STAMAC SAP of the non-AP MLD, and that the correct STA MAC address (the STAMAC address of the STA operating on the same link as the non-MLD) is returned as the hardware MAC address of the non-AP MLD.

[0159] Figure 15 A flowchart 1500 is shown illustrating a second example of communication via AP MLD 1502 for multi-link address resolution between a non-AP MLD 1522 and a non-MLD STA1512, according to a second embodiment of the present disclosure.

[0160] In this second example, a traditional STA (e.g., STA5 1512) is shown resolving the IPv4 address of a non-AP MLD (e.g., non-APMLD2 1522) without a common link. If a non-MLD happens to be operating on a link that is not among the established links of some of the associated non-AP MLDs, the AP MLD has no choice but to forward any group-addressed data frames received from the associated non-MLDs on all established links to all associated non-AP MLDs. This will result in the generation of multiple ARP requests and ARP responses, so the traditional STA's ARP can cache any of the STA's MAC address for the non-AP MLD. In any case, if communication between the traditional STA and the non-AP MLD occurs via the associated AP MLD, the communication will be successful; however, in this case, direct link communication is impossible regardless of ARP caching because there is no direct link between the traditional STA and the non-AP MLD.

[0161] Returning to the example, STA5 operates on link 3, while non-AP MLD2 operates on links 1 and 2. STA5 1512 can initiate an ARP query by generating a first data frame 1532 carrying a broadcast address in its DA field 1535 and an Address Resolution Request (ARP Request) 1534 and sending it to AP MLD 1502 on the 2.4 GHz band (link 3). The broadcast address in the DA field 1535 indicates that the first data frame 1532 is being broadcast to all associated STAs and non-AP MLDs. The ARP Request 1534 carries the IP address of non-AP MLD2 1522 in its destination IP field 1539 to indicate that non-AP STA5 1512 is attempting to resolve that IP address to obtain the corresponding MAC address of non-AP MLD2 1522.

[0162] Next, AP31508, which receives the first data frame 1532 in the 2.4GHz link, can forward the first data frame 1532' carrying an ARP request 1534' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS) that includes STA3 1524, STA4 1526, and STA5 1512 across all three links (2.4GHz, 5GHz, and 6GHz links). The SA field 1535' carries the MAC address of STA5 1512, indicating that the original sender of the first data frame 1534' is STA5 1512.

[0163] Because the destination IP address carried in the destination IP field 1539' of ARP request 1534' matches the IP address (STA-MLD2-IP) of non-AP MLD2 1522, non-AP MLD2 1522 can receive both ARP requests 1534' via STA3 1524 and STA4 1526. Both STA3 1524 and STA4 1524 can identify that ARP request 1534' originates from STA51512 based on the SA field 1535', and determine that the requesting device STA51512 is non-MLD due to the lack of an "ML indication" in the first data frame 1532'. Based on this, ARP request 1534' is forwarded to the MAC SAP of STA3 and STA4.

[0164] Non-AP MLD2 1522 can generate a second data frame 1542 carrying an address resolution response (ARP reply) 1544 via their respective STAMAC SAP, and send the data frame 1542 to AP1 1504 and AP2 1506 via the 5GHz band (link 1) and 6GHz band (link 2) respectively. The two ARP replies 1544 carried in the data frame 1542 generated by STA3 1524 and STA4 1526 carry their respective MAC addresses (STA3-M / STA4-M) in the source hardware field 1546, and carry the MAC address of STA5 in the destination hardware field 1548 and the IP address of STA5 in the destination IP field 1549, indicating that STA5 1512 is the target receiver of the ARP reply 1544.

[0165] AP MLD 1502, receiving two second data frames 1542, identifies the ARP reply 1544 carried in the second data frame 1542 as being directed to STA5 1512 based on the MAC address (STA5-M) in the target hardware field 1548. Then, through AP3 1508 operating on the operational link (link 3) of STA5, it forwards the second data frame 1552' carrying the ARP reply 1544' to STA5 1512. Note that the SA field 1545' of the second data frame 1542' is set to the MAC addresses of STA3 and STA4 to identify the original sending STAs of the second data frame 1542 as STA3 1524 and STA4 1524, respectively.

[0166] STA5 1512, receiving the ARP replies 1544' carried in two second data frames 1542, can process them and update its ARP cache twice to map the non-AP MLD IP address (STA-MLD2-IP) in the source IP field 1547' to the two MAC addresses (STA3-M / STA4-M) in the source hardware field 1546' of the ARP reply 1544'. However, the later updated MAC address (e.g., STA4-M) will remain in the ARP cache as the non-AP MLD2 MAC address.

[0167] Subsequently, STA4 1526, which is not an AP MLD2 1522, can initiate TDLS discovery by sending a follow-up data frame 1552 carrying a TDLS discovery request 1554 to STA5 1512. STA4 1526 acts as the TDLS initiator. The TDLS discovery request 1554 includes a TDLS initiator field set to the MAC address of STA4 and a TDLS responder field 1559 set to the MAC address of STA5 1512.

[0168] AP MLD 1502, receiving subsequent data frame 1522, identifies the TDLS discovery request 1554 carried in data frame 1554 as being directed to STA5 1512 based on the MAC address (STA5-M) of STA5 in the TDLS responder field 1559. It then forwards data frame 1552' (containing the MAC address (STA4-M) of STA4 carried in the SA field 1555', received from non-AP MLD2 1522, and the TDLS discovery request 1554' to STA5 1512 via the STA5's operational link. When forwarding data frame 1552' to STA5 1512, AP MLD 1502 can translate the MAC address (STA5-M) of STA5 in the RA field 1553'. Thus, the data frame is correctly received by STA5 1512.

[0169] STA5 1512, which receives TDLS discovery request 1554, can send TDLS discovery response action frame 1562 on link 3. STA5 1512 sets the RA field 1563 of TDLS discovery response action frame 1562 to the MAC address of STA4 (STA4-M) based on the mapping stored in its ARP cache. However, since non-AP MLD2 does not have any affiliated STAs operating on link 3, frames sent from STA5 1512 to non-AP MLD2 1522 will fail, even if the RA is set correctly.

[0170] Figure 16 A flowchart 1600 is shown illustrating a third example of communication between AP MLD 1602, non-AP MLD 1622 and non-MLD STA1612 for multi-link address resolution according to a second embodiment of the present disclosure.

[0171] The third example and Figure 14 The first example shown is consistent, but takes into account the scenario where the AP MLD 1402 replicates broadcast data frames on all links (link 1 and link 2).

[0172] Even if a non-MLD operates on one of the established links in an associated non-AP MLD, the AP MLD may have no choice but to forward any group-addressed data frames received from the associated non-MLD on all established links due to the presence of other legacy STAs or non-AP MLDs on other links. This results in the generation of multiple ARP requests and ARP responses. However, the AP MLD can help the legacy STA maintain the correct ARP cache by only forwarding ARP responses received on the link in which the legacy STA (addressed in the DA field) is operating. It is also possible for a non-AP MLD to initiate a TDLS discovery / establishment request frame with a legacy STA on the wrong link, unaware of which link the legacy STA is operating on. In this case, the AP MLD can also help the legacy STA by forwarding the TDLS discovery / establishment request frame on the correct link, and may even modify the SA and TDLS initiator fields to reflect the correct STA of the initiating non-AP MLD (a STA operating on the same link as the legacy STA, STA4 in this example). However, this requires the AP MLD to inspect the tunnel data frame and modify the data frame payload.

[0173] In this third example, a conventional STA (e.g., STA5 1612) is shown resolving the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 1622) using a public link (e.g., link 2 or the 6GHz band). STA5 1612 can initiate an ARP query by generating a first data frame 1632 carrying a broadcast address and an Address Resolution Request (ARP Request) 1634 in its DA field 1635 and sending it to AP MLD 1602 on the 6GHz link (band). The broadcast address in the DA field 1635 indicates that the first data frame 1632 is being broadcast to all associated STAs and non-AP MLDs. The ARP Request 1634 carries the IP address of non-AP MLD2 1622 in the destination IP field 1639 to indicate that STA5 1612 is attempting to resolve that IP address to obtain the corresponding MAC address of non-AP MLD2 1622.

[0174] Next, AP21606, which receives the first data frame 1632 on the 6GHz link, can forward the first data frame 1632' carrying an ARP request 1634' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS) that includes STA3 1624, STA4 1626, and STA5 1612 across all links (5GHz and 6GHz links). The SA field 1635' carries the MAC address of STA5 1612 to indicate that the original sender of the first data frame 1634' is STA5 1612.

[0175] Because the destination IP address carried in the destination IP field 1639' of ARP request 1634' matches the IP addresses (STA-MLD2-IP) of STA3 1624 and STA4 1626, non-AP MLD2 can receive two ARP requests 1634' via STA3 1624 and STA4 1626. Both STA3 1624 and STA4 1626 can identify that ARP request 1634' originates from STA5 1612 based on the SA field 1635', and determine that the requesting device STA5 1612 is non-MLD due to the lack of an "ML indication" in the first data frame 1632'. Based on this, ARP request 1634' is forwarded to the MAC SAP of STA3 and STA4.

[0176] STA3 1624 and STA4 1626 can use their respective STAMAC SAPs to generate a second data frame 1642 carrying an address resolution response (ARP reply) 1644, and transmit the data frame 1642 to AP1 1604 and AP2 1606 via the 5GHz band (link 1) and 6GHz band (link 2), respectively. The two ARP replies 1644 carried in the data frame 1642 generated by STA3 1624 and STA4 1626 carry their respective MAC addresses (STA3-M / STA4-M) in the source hardware field 1646, and STA5's MAC address in the destination hardware field 1648 and STA5's IP address in the destination IP field 1649, indicating that STA5 1612 is the target receiver of the ARP reply 1644.

[0177] AP MLD 1602, receiving two second data frames 1642, identifies that the ARP reply 1644 carried in the second data frame 1642 is directed to STA5 1612 based on the MAC address (STA5-M) in the DA field. Note that STA5 1612 operates on Link 2 (6GHz band), and AP MLD 1602 only forwards the second data frame 1642' carrying the ARP reply 1644' received on the operating link of STA5 to STA5 1612 through AP2 1606 operating on the same link, and does not forward the second data frame 1642' carrying the ARP reply 1644' received on another link (Link 1). Note that the SA field 1645' of the second data frame 1662' is set to the MAC address of STA4 to identify that the original sending STA of the second data frame 1642 is STA4 1624.

[0178] The STA5 1612 that receives the ARP reply 1644' carried in the second data frame 1642' can process the ARP reply and update its ARP cache to map the IP address of the non-AP MLD (STA-MLD2-IP) in the source IP field 1647' to the STA4-M in the source hardware field 1646' of the ARP reply 1644'.

[0179] Subsequently, the non-AP MLD2 1622 can initiate TDLS discovery by sending a follow-up data frame 1652 carrying a TDLS discovery request 1654 to STA5 1612 via one of its affiliated STAs (in this case, STA3 1624 via Link 1). The TDLS discovery request 1654 includes a TDLS initiator field set to the MAC address of STA3 and a TDLS responder field 1659 set to the MAC address of STA5 1612.

[0180] AP1 1604, which receives subsequent data frame 1652 via link 1 from AP MLD 1602, identifies the TDLS discovery request 1654 carried in data frame 1652 as being directed to STA5 1612 based on the MAC address (STA5-M) of STA5 in the TDLS responder field 1659. Note that STA5 1612 operates on link 2, and AP1 1604 is able to correct the MAC address in the SA field 1655' and TDLS initiator field 1658' to associate it with STA4 1606 (STA4-M), which operates on the same link as STA5 1612. Furthermore, AP2 1606, which operates on the same link as STA5, forwards data frame 1652', which is received from non-AP MLD2 1622 and carries the corrected SA field 1655' and TDLS initiator field 1658', to STA5 1612. Thus, although the non-AP MLD2 1622 sends data frame 1642 in the wrong link, data frame 1642 is correctly received by STA51612.

[0181] STA5 1612, receiving TDLS discovery request 1654', can send TDLS discovery response action frame 1662 back to the source on the direct link. STA5 1612 is able to set the RA field 1663 of TDLS discovery response action frame 1662 to the MAC address of STA4 (STA4-M) based on the TDLS initiator field 1658'. As a result, TDLS discovery response action frame 1662 sent to non-AP MLD 1622 on the direct link is correctly received by STA4 1626. Thus, communication on the direct link is successful. All subsequent data frames sent by STA5 to non-AP MLD2 via the direct link will also be successful because the RA can be correctly set to STA4 based on STA5's ARP cache, mapping STA-MLD2-IP to STA4-M.

[0182] Figure 17 A flowchart 1700 is shown illustrating a fourth example of communication via AP MLD 1702 for multi-link address resolution between a non-AP MLD 1722 and a non-MLD STA1712 according to a second embodiment of the present disclosure.

[0183] In this fourth example, a conventional STA (e.g., STA5 1712) is shown resolving the IPv6 address of a non-AP MLD (e.g., non-AP MLD2 1722) using a public link (e.g., link 2 or the 6GHz band). The fourth example is similar to the first example except that STA5 1712 resolves an IPv6 address instead of an IPv4 address. STA5 1712 can initiate an ND query by generating a first data frame 1732 carrying a broadcast address in its DA field 1735 and a neighbor request message 1734 and sending it to AP MLD 1702 on the 6GHz link (band). The broadcast address in the DA field 1735 indicates that the first data frame 1732 is being broadcast to all associated APs and AP MLDs. The neighbor request message 1734 carries the IP address of non-AP MLD2 1722 in the destination address field 1738 to indicate that STA5 1712 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 1722.

[0184] Next, AP21704, which receives the first data frame 1732 on the 6GHz link via AP MLD 1702, can forward the first data frame 1732' carrying the neighbor request message 1734' to all associated STAs and / or non-AP MLDs in the Basic Service Set (BSS), including STA51712 and non-AP MLD2 1722. The SA field 1735' carries the MAC address of STA51712 to indicate that the original sender of the first data frame 1734' is STA51712. Since the destination IP address carried in the destination address field of the neighbor request message 1734' received by STA51712 and AP21704 does not match their respective L2 and MLD MAC IP addresses, STA51712 and AP21704 either ignore the neighbor request message 1734' or reject it as a loopback frame.

[0185] On the other hand, since the destination IP address carried in the destination address field 1738' of the neighbor request message 1734' received by STA4 1724 matches its non-AP MLD2 IP address (STA-MLD2-IP), STA4 1724 can identify that the neighbor request message 1734' originates from STA5 1712 based on the SA field 1735', and determine that the requesting device STA5 1712 is a non-MLD due to the lack of "ML indication" in the first data frame 1732'. Based on this, the neighbor request message 1734' is forwarded to the STA4 MAC SAP. The non-AP MLD2 1722 can also record link 2 (6GHz band) as the operating link of STA5.

[0186] STA4 1724 can use its STAMAC SAP to generate a second data frame 1742 carrying a neighbor advertisement message 1734, and send data frame 1742 to AP2 1704 via the operational link. The neighbor advertisement message 1744 carried in data frame 1742 carries its STA4's MAC address (STA4-M) in the destination L2 address field 1446.

[0187] AP MLD 1702, receiving the second data frame 1742, identifies the neighbor advertisement message 1744 carried in the second data frame 1742 as being directed to STA5 based on the MAC address (STA5-M) in the DA field 1745. It then forwards the second data frame 1742' carrying the neighbor advertisement message 1744' to STA51712 via AP2 1704, which operates on the operational link (link 2) of STA5. Note that the SA field 1745' of the second data frame 1742' is set to the MAC address of STA4 to identify the original sending STA of the second data frame 1742 as STA41724.

[0188] STA5 1712, which receives the second data frame 1742, can process it and update its ARP cache to map the non-AP MLD IP address (STA-MLD2-IP) in the destination IP field 1748' to the MAC address (STA4-M) of STA4 in the destination L2 address field 1749' of the neighbor advertisement message 1744'. As a result, the ND query is resolved.

[0189] Subsequently, STA5 1712 can send subsequent data frames (IP packets) 1752 to non-AP-MLD2 1722 via AP MLD 1702. IP packets destined for STA-MLD2-IP will be addressed to STA-4 at the IP layer, where the DA field 1755 of IP packet 1752 is set to the MAC address (STA-4-M) of STA4 1724 at the MLD level.

[0190] AP MLD 1702, receiving IP packet 1752, recognizes that IP packet 1752 is directed to a STA attached to an associated non-AP MLD (in this case, STA4 of non-AP MLD2 1722 based on DA field 1755), and forwards IP packet 1752' received from STA5 1712 to non-AP MLD2 1722 via any of the associated APs (in this case, forwarded to AP2 1704 via the 6GHz link). Note that since non-AP MLD2 1722 is associated with AP MLD 1702, AP MLD 1702 knows the L2 MAC address of STA4 1724, and when forwarding IP packet 1752' to STA4 1724, AP MLD 1702 sets the MAC address of STA4 (STA4-M) in RA field 1753'. Thus, IP packet 1752' will be correctly received by STA4 1724.

[0191] STA4 1724 can identify that data frame 1752' originates from STA5 1712 based on SA field 1755', and determine that the requesting device STA5 1712 is non-MLD because data frame 1752' lacks an "ML indication". Based on this, data frame 1752' is forwarded to STA4 MAC SAP.

[0192] Subsequently, STA5 1712 can send an ANQP request frame 1762 to STA4 1724 on the direct link (i.e., STA5's operational link (link 2)). STA5 1712 is able to set the RA field 1763 of the ANQP request frame 1762 to the MAC address (STA4-M) of STA4 based on the mapping stored in its ARP cache. Thus, the ANQP request frame 1762 sent by STA5 1712 to STA4 1724 on the direct link is correctly received. This solves the problem described in the first embodiment. Figure 9 As shown, frames transmitted on a direct link between a traditional STA and a non-AP MLD cannot be received correctly.

[0193] In the following paragraphs, the third embodiment of this disclosure is explained with reference to multi-link address resolution in AP MLD, non-AP MLD and / or non-MLD STA using the MLD address lookup mechanism.

[0194] As mentioned in the first embodiment, when a non-AP MLD resolves the IP address of another non-AP MLD, since RA is set to the MLD MAC address instead of the STA's MAC address, the ANQP request frame subsequently sent by the non-AP MLD to the other non-AP MLD on the direct link will fail.

[0195] According to a third embodiment of this disclosure, an MLD address lookup mechanism is proposed for performing MLD MAC address to L2 MAC address resolution to solve the above-mentioned problems:

[0196] Non-AP MLDs or EHT STAs can obtain the MLD MAC address of a peer non-AP MLD (e.g., via...). Figure 8The described ARP / ND procedure involves initiating an MLD MAC address query before initiating frame exchange with the peer non-AP MLD on a direct link, requesting the peer non-AP MLD to provide its L2 MAC address (STA MAC address). The presence of the "ML indication" allows the non-AP MLD to recognize that the peer device is an MLD. A non-AP MLD can initiate an MLD MAC address query by sending an MLD address query request frame to the relevant other non-AP MLD via the AP MLD (transparently or non-transparently). Specifically, if a data frame is used to carry the MLD address query, the MLD address query request frame will be transparent to the AP MLD; that is, the AP MLD may not know the content of the frame exchange and simply forwards the data frame based on the DA field. If a management frame is used instead, the MLD address query request / response is opaque.

[0197] Figure 18 A flowchart 1800 illustrates communication between AP MLD 1802 and two non-AP MLDs 1812, 1822 using multi-link address resolution with management frames according to a third embodiment of this disclosure. In this example, STA2 1814 wants to initiate a direct link transmission with non-AP MLD2 1822, but due to the presence of the ML indication in the ARP / ND query, it knows that the peer (non-AP MLD) is MLD and the MAC address of non-AP MLD2, but it does not know the STA attached to non-AP MLD2 1822 and its STA MAC address. STA2 can send an MLD address query request frame 1832 to non-AP MLD2 via AP2 1804 of AP MLD 1802 operating on link 2. MLD address query request frame 1832 carries a target MLD MAC address field 1838, which carries the MAC address of non-AP MLD2 1822 to indicate that non-AP MLD2 1822 is the target recipient of MLD address query request frame 1832.

[0198] AP2 1804, which receives MLD 1832, recognizes that MLD 1832 is directed to an associated non-AP MLD (in this case, non-AP MLD2 based on the MAC address (STA-MLD2-M) in the target MLD MAC address field 1838) and forwards MLD 1832 to non-AP MLD2 1822 using AP2 1804.

[0199] Since the target IP address carried in the target MAC address field 1838' of the MLD address query request frame 1832' received by STA4 1824 matches the MAC address (STA-MLD2-M) of its non-AP MLD2, the non-AP MLD2 1822 can generate an MLD address query response frame 1842 carrying an ML element 1849 including the L2 MAC addresses of all STAs attached to the non-AP MLD2 1822 and the identifier of the operating link, and send it back to the source non-AP MLD1 1812 identified based on the source MAC address field 1839' via AP2 1804.

[0200] AP2 1804, which receives the MLD address query response 1842 from AP MLD 1802, recognizes that the MLD address query response frame 1842 is directed to the associated non-AP MLD (in this case, non-AP MLD2 based on the MAC address (STA-MLD1-M) in the target MLD MAC address field 1848), and forwards the MLD address query response frame 1842' to non-AP MLD1 1812 using AP2 1804.

[0201] STA2 1814, a non-AP MLD1 1812, can receive and process the MLD address query response frame 1842', and record the L2 MAC addresses and operational links of all STAs attached to the non-AP MLD2 1822 in, for example, an MLD address cache. Subsequently, STA2 1814 can send an ANQP request frame 1852 to STA4 1824 on the direct link (link 2). STA2 1814 can set the RA field 1853 of the ANQP request frame 1852 to the L2 MAC address of STA4 (STA4-M) based on the recorded L2 MAC address received in the MLD address query response frame 1842. Thus, the ANQP request frame 1852 sent by STA2 1814 to STA4 1824 on the direct link is correctly received.

[0202] Figure 19An example format of an MLD address query request frame 1900 and an MLD address query response frame 1920 according to a third embodiment of the present disclosure is shown. The MLD address query request frame 1900 includes a frame control field, a duration field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, an HT field, a category field 1902 and an action field 1904, a session token field, a target MLD MAC address field 1906 and a source MAC address field 1908, and an FCS. The frame control field, duration field, address 1 field, address 2 field, address 3 field, sequence control, and HT control field can be grouped into a MAC header; and the category field 1902, action field 1904, session token field, target MLD MAC address field 1906, and source MAC address field 1908 can be grouped into a frame body. The category field 1902 is set to correspond to an EHT action, and the action field 1904 is set to correspond to an MLD address query request. The target MLD MAC address field 1906 is set to the MLD MAC address to be resolved, and the source MAC address field 1908 is set to the MAC address of the sending STA or the MLD MAC address of the sending MLD.

[0203] MLD address query response frame 1920 includes a frame control field, a duration field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, an HT field, a category field 1922 and an action field 1924, a session token field, a destination MAC address field 1926, an ML element 1928, and an FCS. The frame control field, duration field, address 1 field, address 2 field, address 3 field, sequence control, and HT control field can be grouped into a MAC header; and the category field 1922, action field 1924, session token field, destination MAC address field 1926, and ML element 1928 can be grouped into a frame body. The category field 1922 is set to correspond to an EHT action, and the action field 1904 is set to correspond to an MLD address query response. The destination MAC address field 1926 is set to the MAC address of the source MAC address 1908 in the MLD address query request 1900.

[0204] ML element 1928 also includes an element ID field, a length field, an element ID extension field, a multi-link control field including a type subfield 1930 and a bitmap subfield, a public information field including one or more MLD MAC address subfields, and one or more link information fields, each including a link ID subfield and one or more STA MAC address subfields. The type subfield 1926 of the multi-link control field is set to correspond to the MLD address query type, and one or more STA MAC address subfields carried in each link information field (e.g., STA MAC address field 1932) are set to the STA MAC address of the target MLD, while the link ID field carries the identifier of the link in which the STA operates.

[0205] Alternatively, the encapsulated data frames (e.g., Ethernet type 89-0d data frames carrying TDLS payloads) can be used as MLD address query request and response frames. Figure 20 An example format of an Ethernet type 89-0d data frame 2000, 2020 according to a third embodiment of the present disclosure is shown.

[0206] Ethernet type 89-0d data frames include a frame control field, duration field, address 1 field, address 2 field, address 3 field, sequence control field, HT field, logical link control (LLC) field, subnet access protocol (SNAP) field 2002, payload type field 2004, payload field 2006, and FCS. The frame control field, duration field, address 1 field, address 2 field, address 3 field, sequence control field, and HT control field can be grouped into a MAC header; and the LLC field, SNAP field, payload type field, and payload field can be grouped into a frame body. SNAP field 2002 is set to the Ethernet type 89-0d, and payload type field 2004 is set to correspond to TDLS. Payload field 2006 includes a category field 2008, a TDLS action field 2010, a session token field, a destination MLD MAC address field 2012, and a source MAC address field 2014. Category field 2008 is set to correspond to TDLS. The TDLS action field 2010 is set to correspond to the MLD address query request. The target MLD MAC address field 2012 is set to the MLD MAC address to be resolved, and the source MAC address field 2014 is set to the MAC address of the sending STA or the MLD MAC address of the sending MLD.

[0207] As an alternative to the MLD address query request frame 1900, the Ethernet type 89-0d data frame 2000 includes a frame control field, a duration field, an address 1 field, an address 2 field, an address 3 field, a sequence control field, an HT field, a logical link control (LLC) field, a subnet access protocol (SNAP) field 2002, a payload type field 2004, a payload field 2006, and an FCS. The frame control field, duration field, address 1 field, address 2 field, address 3 field, sequence control field, and HT control field can be grouped into a MAC header; and the LLC field, SNAP field, payload type field, and payload field can be grouped into a frame body. The SNAP field 2002 is set to the Ethernet type 89-0d, and the payload type field 2004 is set to correspond to TDLS. The payload field 2006 includes a category field 2008, a TDLS action field 2010, a session token field, a destination MLD MAC address field 2012, and a source MAC address field 2014. The category field 2008 is set to correspond to TDLS. The TDLS action field 2010 is set to correspond to an MLD address query request. The target MLD MAC address field 2012 is set to the MLD MAC address to be resolved, and the source MAC address field 2014 is set to the MAC address of the sending STA or the MLD MAC address of the sending MLD.

[0208] As an alternative to the MLD address query response frame 1920, the Ethernet Type 89-0d data frame 2020 may carry the same fields as those in the Ethernet Type 89-0d data frame used as the MLD address query request frame, except that the payload field 2022 includes the category field 2024, the TDLS action field 2026, the session token field, the destination MAC address field 2028, and the ML element 2030. The category field 2024 is set to correspond to TDLS. The TDLS action field 2026 is set to correspond to the MLD address query response. The destination MAC address field 2028 is set to the MAC address of the source MAC address 1908 carried in the MLD address query request in the Ethernet Type 89-0d data frame 2000. The ML element 2030 may have the same fields as described above. Figure 19 The settings are the same as those in the ML element field 1928 of the MLD address query response frame 1920 shown in the figure.

[0209] In the following paragraphs, the fourth embodiment of this disclosure is explained with reference to the use of single / group bits of their MAC addresses in the address field as “ML indications” for multilink address resolution in AP MLDs, non-AP MLDs, and / or non-MLD STAs.

[0210] In the address field of the data and management frames that carries the MAC address of the sending / originating STA, a single / group bit (b0) of the MAC address is used as an "ML indicator" to distinguish between the L2 MAC address of the sending / originating STA and the MLD MAC address of the associated MLD. Figure 21 An example architecture 2100 of a MAC address according to a fourth embodiment of this disclosure is shown. The MAC address comprises six octets. The first three octets 2102 are Organization Unique Identifiers (OUIs), and the last three octets 2104 are numbers specific to a device known as a Network Interface Controller (NIC). The first octet 2106 of the three OUI octets 2102 contains eight bits b0-b7, where bit b0 2108, i.e., the least significant bit, is the individual / group bit. The individual / group (b0) bit 2108 can be set and used as an “ML indicator.” Specifically, bit b0 is set to 0 to indicate an L2 MAC address and 1 to indicate an MLD MAC address. Note that bit b0 (individual / group bit) is also used to indicate “bandwidth signaling TA” in some control frames, but it is not used in data and management frames, and therefore can be used as an “ML indicator.”

[0211] When a non-AP MLD sends frames to a peer device, the b0 bit in the TA field of the frame sent to another non-AP MLD in a direct link should be set to 1; while when an AP MLD relays a data frame sent from a non-AP MLD to another non-AP MLD, the b0 bit in the SA field of the data frame should be set to 1. The b0 bit should not be set to 1 in frames addressing (pre-EHT) legacy STAs or non-MLD EHT STAs. Note that in data / management frames of pre-EHT STAs, the b0 bit is always set to 0.

[0212] If the b0 bit of a frame received from the peer is set to 1, the receiving MLD is informed that the sending / originating device is an MLD; otherwise, it is a traditional STA or a non-MLD EHT STA. The MLD needs to recover the MLD MAC address by setting the b0 bit to 0, and then can take further actions such as forwarding to the correct MAC SAP or attempting to resolve the peer MLD's L2 MAC address.

[0213] If the same MAC address is used as both the MLD MAC address and the L2 MAC address, it doesn't matter how the b0 bit is set, because in both cases, the same MAC address is mapped to the IP address.

[0214] Additionally, when a non-AP MLD sends a frame to a peer device, it may, for example, set bit b0 to 1 in any address field (including the address field carried in the payload of the data frame) within the TDLS Initiator / TDLS Responder field of the TDLS Discover / Establish frame. If the sending non-AP MLD does not set bit b0, the AP MLD associated with the sending non-AP MLD may help, for example, set bit b0 to 1 in the address field within the TDLS Initiator / TDLS Responder field of the TDLS Discover / Establish frame, which carries the MLD MAC address of the sending MLD (including the address field carried in the payload of the data frame) in frames relayed by the AP to another non-AP MLD.

[0215] Additionally, if bit b0 of a frame received from a peer device is set to 1, the target application (TDLS) receiving the MLD is notified that the sending / originating device is an MLD; otherwise, it is a traditional STA. Receiving an MLD requires restoring the originating MLD MAC address by setting bit b0 back to 0. If the originating device is an MLD, the application can take further action, such as performing an MLD address lookup to request the STA MAC address of the peer MLD.

[0216] According to this disclosure, the ARP / ND protocol for MLD is "enhanced" to be MLD-aware. Advantageously, the MLD-aware ARP / ND protocol allows adaptive hardware resolution to work correctly, even when a single MLD MAC SAP is used by a legacy STA. Specifically, the ARP / ND protocol sets bit b0 to 1 in the source hardware address field of the sent ARP / ND message. The hardware MAC address returned by the ARP / ND protocol depends on the requesting device. If the requesting device is an MLD (e.g., known by bit b0 in the source hardware address set to 1 in the request frame), ARP / ND returns the MLD's MLD MAC address as its hardware MAC address. If the requesting device is not an MLD (e.g., known by bit b0 in the source hardware address set to 0 in the request frame), ARP / ND returns the MAC address of the associated STA of the MLD operating on the link where the request frame was received, where the MAC address of the associated STA of the MLD can be provided to the ARP / ND protocol by the MLD along with the ARP / ND message.

[0217] Furthermore, if the b0 bit in the resolved hardware address is set to 1, ARP / ND is informed that the peer is an MLE; otherwise, it is a traditional STA. MLE needs to recover the original MLD MAC address by setting the b0 bit back to 0. However, this "enhanced" version of the ARP / ND protocol can only be used if all systems are using the modified ARP / ND protocol, because traditional ARP / ND does not understand that b0 is used as an ML indicator and may log incorrect MLD MAC addresses.

[0218] Figure 22 A flowchart 2200 is shown illustrating communication between AP MLD 2202 and two non-AP MLDs 2212, 2222 for multi-link address resolution according to a fourth embodiment of the present disclosure.

[0219] This example illustrates a non-AP MLD (e.g., non-AP MLD1 2212) resolving the IPv4 address of another non-AP MLD (e.g., non-AP MLD2 2222). STA2 2214 of non-AP MLD1 2212 can initiate an ARP query by generating a first data frame 2232 carrying an ARP request 2234 and sending it via AP2 2204 of AP MLD 2202 on link 2 (6GHz band). The ARP request 2234 includes a source hardware field 2236 carrying the MAC address of non-AP MLD1 (STA-MLD1-M), where bit b0 is set to 1 as an "ML indication". When forwarding data frame 2232, the AP MLD can also set bit b0 of the SA field to 1 to indicate that the originating device is an MLD. STA4 2224 of non-AP MLD2 2222 receives the first data frame 2232 on link 2. Since the destination IP field 2239 of the first data frame 2232 matches the IP address of the non-AP MLD2 2222, STA4 2224 generates a second data frame 2242 carrying an ARP response 2244 and sends the data frame 2242 back to the non-AP MLD1 2212 via AP2 2204. Because the requesting device is known to be MLD due to the presence of the "ML indication," the generated ARP response 2242 includes a source hardware field 2246 carrying the MLD MAC address (STA-MLD2-M) of the non-AP MLD2. Furthermore, bit b0 of the MLD MAC address is set to 1 as the "ML indication," indicating that the non-AP MLD2 2222 is an MLD.

[0220] STA2 2214, which receives the second data frame 2242, can process the non-AP MLD2 MLD MAC address in the source hardware field 2246 of the ARP reply 2242, for example, by restoring the original MLD MAC address by setting bit b0 back to 0, and updating its ARP cache to map the non-AP MLD2 IP address (STA-MLD2-IP) in the source IP field 2247 to the non-AP MLD2 MAC address (STA-MLD2-M). As a result, the ARP query is resolved.

[0221] Subsequently, non-AP MLD1 2212 can initiate TDLS discovery by sending a subsequent data frame 2252 carrying a TDLS discovery request 2254 to non-AP MLD2 2222 via one of its affiliated STAs (in this case, from STA2 2214 to STA4 2224 via AP2 2204 on link 2). The TDLS discovery request 2254 includes a TDLS initiator field 2258 set to the MAC address of non-AP MLD1 (STA-MLD1-M), with bit b0 set to 1 as "ML indication," and a TDLS responder field 2259 set to the MAC address of non-AP MLD2 2222. When forwarding data frame 2252, AP MLD can also set bit b0 of the SA field to 1 to indicate that the originating device is MLD. Frame 2252 sent via AP MLD is correctly received by non-AP MLD2 22222.

[0222] It should be noted that, due to the presence of an "ML indication" in the data frame carrying the TDLS discovery request 2254, the non-AP MLD22222 knows that the peer device is MLD, but it does not know the STAMAC address of the non-AP MLD12212. Therefore, before sending a TDLS discovery response action frame on the direct link in response to the TDLS discovery request 2254, the non-AP MLD2222 sends an MLD address query request frame 2262 to the non-AP MLD12212 via AP2204.

[0223] Since the target IP address carried in the target MAC address field 2268 of the MLD address query request frame 2262 received by STA2 2214 matches the MAC address (STA-MLD1-M) of its non-AP MLD1, STA2 2214 can generate an MLD address query response frame 2272 carrying an ML element 2279 including the L2 MAC addresses (STA1-M and STA2-M) of all STAs attached to the non-AP MLD1 2212, and send it back to the non-AP MLD2 2222.

[0224] STA4 2224, a non-AP MLD2 2222, can receive and process the MLD address query response frame 2272 and record the L2 MAC address and operational link of the non-AP MLD1 2212, for example, in its MLD address cache. STA4 2224 can then send a TDLS discovery response action frame 2282 to STA2 2214 on the direct link (link 2). STA4 2224 is able to correctly set the RA field 2283 of the TDLS discovery response action frame 2282 to the L2 MAC address of STA2 (STA2-M) based on the recorded L2 MAC address received in the MLD address query response frame 2272. This results in the correct reception of the TDLS discovery response action frame 2282 sent by STA4 2224 to STA2 2214 on the direct link.

[0225] Figure 23 A flowchart illustrating communication between AP MLD2302, non-AP MLD 2312 and non-MLD STA 2322 for multi-link address resolution according to a fourth embodiment of the present disclosure is shown.

[0226] This example illustrates an EHT non-MLD STA (e.g., STA5 2312) that resolves the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 2322). Also in this example, it is assumed that the non-AP MLD2 2322 uses a single MLD MAC SAP for both MLD and non-MLD connections; that is, it always returns the MLD MAC address as its hardware address.

[0227] STA6 2312 can initiate an ARP query by generating a first data frame 2332 carrying an ARP request 2334 and sending it to non-AP MLD2 2322 via AP2 2304 on Link 2 (6GHz band) of AP MLD2 2302. The ARP request 2334 includes a source hardware field 2336 (with bit b0 kept at 0) carrying STA6's MAC address. STA4 2324 of non-AP MLD2 2322 receives the first data frame 2332 on Link 2. Since the destination IP field 2339 of the first data frame 2332 matches the IP address of non-AP MLD2 2322, STA4 2324 generates a second data frame 2342 carrying an ARP response 2344 and sends data frame 2342 back to non-AP MLD1 2302 via AP2 2304. Similarly, ARP response 2342 includes a source hardware field 2346 carrying the MAC address (STA-MLD2-M) of a non-AP MLD2.

[0228] STA6 2312, which receives the second data frame 2342, can process the non-AP MLD2 MLD MAC address in the source hardware field 2346 of the ARP reply 2342 and update its ARP cache to map the non-AP MLD2 IP address (STA-MLD2-IP) in the source IP field 2347 to the non-AP MLD2 MAC address (STA-MLD2-M). As a result, the ARP query is resolved.

[0229] Subsequently, non-AP MLD2 2322 can initiate TDLS discovery by sending a subsequent data frame 2352 carrying a TDLS discovery request 2354 to STA6 2312 via one of its affiliated STAs (in this case, via AP2 2304 from STA4 2324 to STA6 2312 on link 2). The TDLS discovery request 2354 includes a TDLS initiator field 2358 set to the MAC address of non-AP MLD2 (STA-MLD2-M), where bit b0 is set to 1 as an "ML indication" to indicate that non-AP MLD2 2322 is an MLD, and a TDLS responder field 2359 set to the MAC address of STA5 2312. Frame 2352 sent via AP MLD is correctly received by STA5 2312.

[0230] It is worth noting that, because of the presence of an "ML indication" in the data frame carrying the TDLS discovery request, STA6 2312 knows that the peer device is MLD, but it does not know the correct STA MAC address of the non-AP MLD2 2322. Therefore, before sending the TDLS discovery response action frame in response to the TDLS discovery request 2352, STA5 2312 sends an MLD address query request frame 2362 to the non-AP MLD2 2322 via AP2 2304.

[0231] Since the target IP address carried in the target MAC address field 2368 of the MLD address query request frame 2362 received by STA4 2324 matches the MLD MAC address (STA-MLD2-M) of non-AP MLD1, STA4 2324 can generate an MLD address query response frame 2372 carrying an ML element 2379 that includes the L2 MAC addresses (STA3-M and STA4-M) of all STAs attached to non-AP MLD2 2322 and the identifier of the operating link, and send it back to STA6 2312.

[0232] STA5 2312 can receive and process MLD address query response frame 2372, and record the L2 MAC address and operational link of the non-AP MLD2 2322 in, for example, its MLD address cache. STA5 2312 can then send TDLS discovery response action frame 2382 to STA4 2324 on the direct link (link 2). STA5 2383 is able to set the RA field 2383 of TDLS discovery response action frame 2382 to the L2 MAC address of STA4 (STA4-M) based on the recorded L2 MAC address received in MLD address query response frame 2372. This results in the correct reception of TDLS discovery response action frame 2382 sent by STA6 2312 to STA4 2324 on the direct link. Similarly, this TDLS establishment can allow another data frame 2392 from STA4 2324 (non-AP MLD2 2322) to STA6 2312 on the direct link.

[0233] This example is meant to emphasize that an EHT STA (non-MLD), even when operating on a single link, can correctly operate on a direct link with a non-AP MLD that doesn't specifically consider single-link devices (e.g., responding to ARP requests from a single-link device by returning its MLD MAC address instead of its L2 MAC address). It does this because it can leverage EHT features such as ML indication and MLD address lookup, and rarely needs the assistance of an AP MLD (e.g., by setting the ML indication in the SA field of the forwarded frame). Here, it is also shown that even if an MLD address lookup request is forwarded by an AP MLD on the wrong link, and subsequently an MLD address response is sent by a non-AP MLD on the wrong link, the response frame is correctly received by the EHT STA, and it can extract the correct L2 (STA) MAC address of the non-AP MLD based on the link ID, because the EHT STA is able to decode the AP MLD's beacon frames, etc., and can calculate the link ID assigned to the different links.

[0234] In the following paragraphs, the fifth embodiment of this disclosure is explained with reference to multi-link address resolution in AP MLDs, non-AP MLDs, and / or non-MLD STAs with proxy ARP features.

[0235] When the AP MLD enables the Proxy ARP service, the AP MLD maintains a hardware-to-Internet address mapping for each associated station (non-AP MLD and non-MLDSTA) and updates this mapping whenever the Internet address of an associated station changes. When an IPv4 address resolved in an ARP request or ARP probe, or an IPv6 address resolved in a neighbor request message, is currently in use by a non-AP STA associated with the BSS, the Proxy ARP service will respond to the ARP request, ARP probe, or neighbor request message on behalf of the STA.

[0236] When an AP MLD receives an ARP request from a DS or a station associated with a request that has a target IP address corresponding to an associated non-AP MLD, the AP MLD will determine whether the requesting station is a non-AP MLD and (i) if the requesting station is a non-AP MLD or the request comes from a DS, insert the non-AP MLD's MLD MAC address as the sender's MAC address into the ARP response packet, or (ii) if the requesting station is a non-MLD STA or is not an MLD, insert the MAC address of the non-AP MLD STA operating on the link in which the request is received as the sender's MAC address into the ARP response packet.

[0237] Similarly, when an AP MLD receives a neighbor request message from a DS or a station associated with a request that has a target IP address corresponding to the associated non-AP MLD, the AP MLD will determine whether the requesting station is a non-AP MLD, and (i) if the requesting station is a non-AP MLD or the request comes from a DS, insert the non-AP MLD's MLD MAC address as the sender's MAC address into the neighbor advertisement message, or (ii) if the requesting station is a non-MLD STA or is not an MLD, insert the MAC address of the non-AP MLD STA operating on the link in which the request is received as the sender's MAC address into the neighbor advertisement message.

[0238] In addition, AP MLD sets the least significant bit b0 (individual / group bit) of the sender's MAC address to 1 to indicate the MLD MAC address in the ARP response packet or neighbor advertisement message sent on behalf of the associated MLD.

[0239] According to the fifth embodiment, when the AP MLD enables its proxy ARP feature, the AP MLD can also respond to MLD address query requests on behalf of the associated non-AP MLD or non-MLD STA. When the MLD MAC address resolved in the MLD address query request is used by a non-AP MLD or non-MLD STA currently associated with the AP MLD, the proxy ARP service can respond to the MLD address query request on behalf of the non-AP MLD or non-MLD STA.

[0240] Specifically, when the AP MLD receives an MLD address query request frame from a station associated with a request that has a target MLD MAC address corresponding to the associated non-AP MLD or non-MLD STA, the AP MLD will construct an ML element carrying the STA MAC addresses of all affiliated STAs of the associated non-AP MLD, the identifier of the operating link, and the corresponding link ID; and respond to the station associated with the request with an MLD address query response frame carrying the ML element.

[0241] While it's natural for the MLD address lookup feature to be packaged within the proxy ARP service, since MLD address lookup is a new feature in EHT, the AP MLD can enable this feature even if it doesn't support the proxy ARP service; that is, the MLD address lookup feature can be decoupled from the proxy ARP service. Furthermore, the AP MLD implementing the proxy ARP service can also implement the transmission of gratuitous ARP / unsolicited neighbor advertisements. A gratuitous ARP request is an ARP request packet where both the source IP and destination IP are set to the IP of the machine that published the packet, and the destination MAC is the broadcast address ff:ff:ff:ff:ff:ff. Typically, no ARP reply packets will appear. An unsolicited ARP reply is a response to a request that hasn't been made. Similarly, an unsolicited neighbor advertisement is a message sent without being requested by anyone, i.e., without a corresponding neighbor request message being received. When enabled, when the IP address or MLD MAC address of the associated non-AP MLD changes, the AP MLD can also send unsolicited ARP packets or unsolicited neighbor advertisements carrying the associated non-AP MLD's MLD MAC address as the hardware address. Typically, these are sent to the broadcast address or the all-hosts multicast address (ff02::1). This can cause associated legacy STAs to incorrectly update their ARP caches using the MLD MAC address (instead of the STA MAC address). To prevent this, the AP MLD will follow the broadcast unsolicited ARP or multicast unsolicited neighbor advertisement with a unicast unsolicited ARP or unicast unsolicited neighbor advertisement message carrying the correct STA MAC address as the sender's hardware address to each associated legacy STA. Alternatively, broadcast transmission of unsolicited ARP / unsolicited neighbor advertisements is not implemented for EHT APs / APMLDs.

[0242] Figure 24AA flowchart illustrating communication between distribution system 2402, AP MLD 2412 and non-AP MLD 2422 for multi-link address resolution according to a fifth embodiment of the present disclosure is shown.

[0243] In this example, AP MLD 2412 is shown representing the resolution of an ARP request from a DS (e.g., PC 2402) on behalf of an associated non-AP MLD (e.g., non-AP MLD1 2422). PC 2402 can initiate an ARP query to resolve the IP address of the non-AP MLD1 2422 associated with AP MLD 2412 by generating an Ethernet frame 2432 carrying an ARP request 2434 and sending it to AP MLD 2412 connected to PC 2402 via Ethernet interface (I / F) 2404. The ARP request 2434 includes a source hardware field 2436 carrying the MAC address (PC-M) of the PC and a destination IP field 2439 carrying the IP address of the non-AP MLD1 2422 (STA-MLD1-IP) to indicate that PC 2402 is attempting to resolve the IP address of the non-AP MLD1 2422.

[0244] Since the destination IP field 2439 of the first data frame 2432 matches the IP address of its associated non-AP MLD 22422, AP MLD 2412 can generate a second data frame 2442 carrying an ARP response 2444, and provide the MLD MAC address (STA-MLD1-M) of the non-AP MLD1 2422 as its hardware address in the source hardware field 2446 of the ARP response 2444, and send the second data frame 2442 back to PC 2402 via Ethernet I / F 2404 through AP2 2422.

[0245] The PC 2402, which receives the second data frame 2442, can process the MLD MAC address of the non-AP MLD1 carried in the source hardware field 2446 of the ARP reply 2442 and update its ARP cache to map the IP address (STA-MLD1-IP) of the non-AP MLD1 in the source IP field 2447 to the MLD MAC address (STA-MLD1-M) of the non-AP MLD1. As a result, the ARP query is resolved without exchanging data frames with the non-AP MLD1 2422.

[0246] Subsequently, PC 2402 may wish to send data to non-AP MLD1 2422 via AP MLD2412 by sending a subsequent Ethernet frame 2452 to AP MLD2412. PC 2402 is able to set the Destination (Dest.) field of Ethernet frame 2452 to the MLD MAC address of non-AP MLD1 based on the mapping stored in its ARP cache. AP MLD 2412, receiving the subsequent Ethernet frame 2452, can generate a corresponding data frame 2456, translate the MLD MAC address of non-AP MLD1, and set the STA MAC address of one of the affiliated STAs of non-AP MLD1 2422 (in this case, the MAC address of STA22424 (STA2-M)) in the RA field 2457 of data frame 2456, and forward data frame 2456 to non-AP MLD1 2422. Because the RA field of data frame 2456 matches the RA field of STA2 2424, data frame 2456 is correctly received by STA2 2424.

[0247] Figure 24B A flowchart illustrating communication between distribution system 2402, AP MLD 2404 and non-MLD STA 2426 for multi-link address resolution according to a fifth embodiment of the present disclosure is shown.

[0248] In this example, AP MLD 2412 is shown representing an associated non-MLD STA (e.g., STA5 2426) resolving an ARP request from a DS (e.g., PC 2402). PC 2402 can initiate an ARP query to resolve the IP address of the non-AP MLD1 2422 associated with AP MLD 2412 by generating an Ethernet frame 2462 carrying an ARP request 2464 and sending it to AP MLD 2412 connected to PC 2402 via Ethernet interface (I / F) 2404. ARP request 2464 includes a source hardware field 2466 carrying the MAC address of PC (PC-M) and a destination IP field 2439 carrying the IP address of STA5 2426 (STA5-IP) to indicate that PC 2402 is attempting to resolve the IP address of STA5 2426.

[0249] Since the destination IP field 2469 of the first data frame 2462 matches the IP address of its associated STA5 2426, AP MLD 2412 can generate a second data frame 2472 carrying an ARP response 2474, and provide the MLD MAC address (STA5-M) of STA5 2426 as its hardware address in the source hardware field 2476 of the ARP response 2474, and send the second data frame 2472 back to PC 2402 via Ethernet I / F 2404 through AP2 2422.

[0250] The PC 2402, which receives the second data frame 2472, can process the MAC address of STA5 carried in the source hardware field 2476 of the ARP reply 2472 and update its ARP cache to map the IP address (STA5-IP) of STA5 in the source IP field 2477 to the MAC address (STA5-M) of STA5. As a result, the ARP query is resolved without exchanging data frames with STA5 2426.

[0251] Subsequently, PC 2402 may wish to send data to STA5 2426 via AP MLD 2412 by sending a subsequent Ethernet frame 2482 to AP MLD 2412. PC 2402 is able to set the destination field of Ethernet frame 2482 to the MAC address of STA5 based on the mapping stored in its ARP cache. AP MLD 2412, receiving the subsequent Ethernet frame 2482, can generate a corresponding data frame 2486, set the MAC address of STA5 in the RA field 2487 of data frame 2486, and forward it to STA5. Since the RA field of data frame 2486 matches the RA field of STA5 2426, data frame 2486 is correctly received by STA5 2426.

[0252] Figure 25 A flowchart 2500 is shown illustrating a first example of communication between AP MLD 2502, non-AP MLD 2522 and non-MLD STA 2512 for multi-link address resolution according to a fifth embodiment of the present disclosure.

[0253] In this first example, an AP MLD is shown representing a non-AP MLD (e.g., non-AP MLD2 2522) resolving a neighbor request message from a non-MLDSTA (e.g., STA5 2512).

[0254] STA5 2512 can initiate an ND query by generating a first data frame 2532 carrying a neighbor request message 2534 and sending it to AP MLD 2502 on Link 2 (6GHz band). The neighbor request message 2534 carries the IP address of non-AP MLD2 2522 in the destination address field 2568 to indicate that STA5 2512 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 2522.

[0255] Next, AP22504, which receives the first data frame 2532 on the 6GHz link, can identify the requesting STA (i.e., STA5 2512) as a traditional STA based on the source L2 address field of the neighbor request message 2534, and the destination IP address carried in the destination address field 2538 of the neighbor request message 2534 matches the address of its associated non-AP MLD1 2522 IP. Therefore, AP22504 can generate a second data frame 2542 carrying the neighbor advertisement message 2534, and provide the STA MAC address (STA4-M) of the non-AP MLD2 2522 corresponding to the link (i.e., link 2) of STA5, instead of the MLD MAC address, as its hardware address in the destination L2 address 2549 of the neighbor advertisement message 2544, and send the second data frame 2542 back to STA5 2512 via the operational link of STA5 through AP2 2504.

[0256] Note that since a non-AP MLD (e.g., non-AP MLD2 2522) contains multiple STA MAC addresses, the AP MLD will return the STA MAC address of the Attached STA of the Non-AP MLD operating on the common link as the hardware address (target L2 address) of the Non-AP MLD, provided a common link exists between the requesting legacy STA (e.g., STA5 2512) and the target Non-AP MLD. This ensures that the legacy STA and the Non-AP MLD can communicate on a direct link (on the common link). However, if no common link exists between the legacy STA and the Non-AP MLD, the AP MLD may return the MLD MAC address of the Non-AP MLD or any MAC address of the Attached STA as the hardware address (target L2 address) of the Non-AP MLD.

[0257] STA5 2512, which receives the second data frame 2542 sent by AP MLD 2502 on behalf of non-AP MLD2 2522, can process the STA MAC address carried in the target L2 address 2549 of the neighbor advertisement message 2544 and update its neighbor cache to map the non-AP MLD2 IP address (STA-MLD2-IP) in the target address field 2548 to the L2 MAC address (STA4-M) in the target L2 address field 2549. As a result, the ND query is resolved without exchanging data frames with non-AP MLD2 2522.

[0258] Subsequently, STA5 2512 can initiate TDLS discovery by sending a follow-up data frame 2552 carrying a TDLS discovery request 2554 to non-AP MLD2 2522 via AP MLD 2502. The STA MAC address (STA4-M) of non-AP MLD2 2522 stored in the neighbor cache is used in the DA / SA field 2555 of data frame 2552 and the TDLS responder field 2559 (DA field = TDLS responder field) of TDLS discovery request 2554.

[0259] AP2 2504 of AP MLD 2502 can identify, based on the STA MAC address, that subsequent data frame 2552 is directed to its associated non-AP MLD2 2522 STA4 2524, and forward data frame 2552 to STA4 2524. AP MLD 2502 can set the RA field 2553 of data frame 2552 before forwarding data frame 2552 to STA4 2524. In this way, data frame 2552 is correctly received by non-AP MLD2 2522 via AP MLD 2502.

[0260] In response, the non-AP MLD 2522 can send a TDLS discovery response action frame 2562 on the direct link (link 2), in which the TA field 2563 and the TDLS responder field 2569 are set to the STA MAC address of the attached STA (in this case, STA4 2524) that sent the TDLS discovery response action frame 2562.

[0261] Furthermore, since the TA field 2563 and the TDLS responder field 2569 in the link identifier element of the TDLS discovery response frame 2562 relayed on the direct link are both set to the same STA MAC address (STA4-M), no confusion occurs at the receiving location of a legacy STA (STA5 2512). This effectively resolves the second address mismatch issue when a legacy STA initiates a TDLS establishment with a non-AP MLD without requiring changes to the RA / TA setting rules or the use of the MLD MAC address in the TDLS initiator or TDLS responder fields.

[0262] Additionally, since both the DA and TDLS responder fields are set to the STA MAC address (STA4-M) of the peer device, the AP MLD 2502 can correctly identify the link (link 2) to which the TDLS discovery / establishment request frame should be forwarded, and therefore no link crossover issues will occur.

[0263] Subsequently, STA5 2512 can initiate TDLS establishment with STA4 2524 via AP MLD 2502 by sending another data frame 2572 carrying a TDLS establishment request 2574 to AP MLD 2502. The STA MAC address (STA4-M) of the non-APMLD2 2522 stored in the neighbor cache is used to set the DA field 2576 of data frame 2572 and the TDLS responder field 2579 of TDLS establishment request 2574 (DA = TDLS responder).

[0264] AP2 2504 of AP MLD 2502 can identify, based on the STA MAC address, that another data frame 2572 is directed to its associated non-AP MLD2 2522 STA4 2524, and forward the other data frame 2572 to STA4 2524. Before forwarding data frame 2572 to STA4 2524, AP MLD2502 can set the RA field 2553 of data frame 2572 to the STA MAC address (STA4-M) of the non-AP MLD2 2522 corresponding to the link (i.e., link 2) of STA5. Therefore, data frame 2572 is correctly received by non-AP MLD2 2522 via AP MLD 2502.

[0265] In response, the non-AP MLD 2522 can send another data frame 2582 carrying a TDLS establishment response 2584 on the direct link (link 2), where the DA field 2586 and the TDLS initiator field 2588 are set to the MAC address in the TDLS initiator field 2578 of the TDLS establishment request 2574. Thus, TDLS between STA4 2524 and STA5 2512 is successfully established, and the non-MLD STA (STA5 2512) and the non-AP MLD STA (STA4 2524 of the non-AP MLD2 2522) can send and receive data frames 2592 on the direct link, because the RA field 2593 of data frame 2592 can be correctly set to the STA MAC address (STA4-M and STA5-M) accordingly.

[0266] Figure 26 A flowchart 2600 is shown illustrating a second example of communication between AP MLD 2602 and two non-AP MLDs 2612, 2622 for multi-link address resolution according to a fifth embodiment of the present disclosure.

[0267] In this second example, AP MLD 2602 is shown resolving ARP requests and MLD address lookup requests from a non-AP MLD (e.g., non-AP MLD2 2622) on behalf of another non-AP MLD (e.g., non-AP MLD1 2612).

[0268] STA2 2614, a non-AP MLD1 2612, can initiate an ARP query by generating a first data frame 2632 carrying an ARP request 2634 and sending it to non-AP MLD2 2622 via AP MLD 2602 on Link 2 (6GHz band). The ARP request 2634 includes a source hardware field 2636 carrying the MAC address of non-AP MLD1 (STA-MLD1-M) and a destination IP field 2639 carrying the IP address of non-AP MLD2 (STA-MLD2-IP), indicating that non-AP MLD1 2612 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 2622.

[0269] Next, AP22604, which receives the first data frame 2632 on the 6GHz link, can identify the requester (i.e., non-AP MLD1 2612) as MLD based on the source hardware field 2636 of the ARP request 2634, and the destination IP address carried in the destination IP field 2639 of the ARP request 2634 matches the IP address of its associated non-AP MLD2. Therefore, AP MLD 2602 can generate a second data frame 2642 carrying an ARP response 2644, and provide the MLD MAC address (STA-MLD2-M) of non-AP MLD2 2622 as its hardware address in the source hardware field 2646 of the ARP response 2644, and set the b0 bit of the MLD MAC address to 1 for ML indication before sending the second data frame 2642 back to non-AP MLD1 2612.

[0270] The non-AP MLD1 2612, receiving the second data frame 2642, can process the ARP reply 2642 and, due to the presence of the ML indication in bit b0, begins to know that the MAC address carried in the source hardware field 2646 is an MLD MAC address. Then, the non-AP MLD1 2612 can recover the original MLD MAC address by setting bit b0 back to 0 and updating its ARP cache to map the IP address of the non-AP MLD2 (STA-MLD2-IP) in the source IP field 2647 to the MLD MAC address of the non-AP MLD2 (STA-MLD2-M) in the source hardware field 2646. As a result, the ARP query is resolved, and due to the presence of the ML indication, STA2 2614 now knows that STA-MLD2-M is an MLD MAC address without exchanging data frames with the non-AP MLD2 2622.

[0271] Since non-AP MLD1 2612 begins to know that non-AP MLD2 2622 is an MLD based on the ML indication in bit b0 of its MLD MAC address, non-AP MLD1 2612 initiates an MLD address query to obtain the STAMAC address of non-AP MLD2 2622 by sending an MLD address query request frame 2652 to non-AP MLD2 2622 via AP2 2604 of AP MLD 2602.

[0272] AP MLD 2602 can identify the associated non-AP MLD (in this case, non-AP MLD2 2622) from the target MLD MAC address field, and resolves the MLD MAC address on behalf of non-AP MLD2 2622 by generating an MLD address query response carrying ML element 2669, which includes the L2 MAC addresses (STA3-M and STA4-M) of all STAs attached to non-AP MLD2 2622 and the identifier of the operating link, and sending it back to non-AP MLD1 2612.

[0273] STA2 2614, a non-AP MLD1 2614, can receive and process the MLD address query response frame 2662 and record the L2 MAC addresses of all STAs attached to the non-AP MLD2 2622 in, for example, their MLD address cache. STA2 2614 can then send an ANQP request frame 2672 to STA4 2624 on the direct link (link 2). STA2 2614 can set the RA field 2673 of the ANQP request frame 2672 to the L2 MAC address of STA4 (STA4-M) based on the recorded L2 MAC address received in the MLD address query response frame 2662. Thus, the ANQP request frame 2672 sent by STA2 2614 to STA4 2624 on the direct link is correctly received.

[0274] Figure 27 A flowchart 2700 is shown illustrating a third example of multi-link resolution communication between AP MLD 2702, non-AP MLD 2712, and non-MLD STA 2722 according to a fifth embodiment of the present disclosure.

[0275] In this third example, AP MLD 2702 is shown representing a conventional STA (e.g., STA5 2722) resolving ARP requests from a non-AP MLD (e.g., non-AP MLD2 2712).

[0276] STA4 2714, which is not an AP MLD2 2712, can initiate an ARP query by generating a first data frame 2732 carrying an ARP request 2734 and sending it to STA5 2722 via AP MLD 2702 on Link 2 (6GHz band). The ARP request 2734 includes a source hardware field 2736 carrying the MAC address of the non-AP MLD2 (STA-MLD2-M) and a destination IP field 2739 carrying the IP address of STA5 (STA5-IP), indicating that the non-AP MLD2 2712 is attempting to resolve the IP address to obtain the corresponding MAC address of STA5 2722.

[0277] Next, AP22704, which receives the first data frame 2732 on the 6GHz link, can identify the requester (i.e., non-AP MLD2 2712) as MLD based on the source hardware field 2736 of the ARP request 2734, and the destination IP address carried in the destination IP field 2739 of the ARP request 2734 matches the IP address of its associated STA5. Therefore, APMLD 2702 can generate a second data frame 2742 carrying an ARP response 2744, and provide the L2 MAC address (STA5-M) of STA5 as its hardware address in the source hardware field 2746 of the ARP response 2744 (keeping the b0 bit of the MAC address 0), and send the second data frame 2742 back to non-AP MLD22712.

[0278] The non-AP MLD2 2712, receiving the second data frame 2742, can process the ARP reply 2744 and, due to the missing ML indication in bit b0, begins to know that the MAC address carried in the source hardware field 2746 is the STA MAC address, not the MLD MAC address. The non-AP MLD1 2712 can update its ARP cache to map the IP address of STA5 (STA5-IP) in the source IP field 2747 to the L2 MAC address of STA5 (STA5-M) in the source hardware field 2746. As a result, the ARP query is resolved, and STA4 2714 now knows that STA5 2722 is a non-MLD or legacy STA without exchanging data frames with STA5 2722.

[0279] Advantageously, since the STA5 2722 never receives ARP requests 2732, it does not perform any opportunistic ARP cache updates on non-AP MLD22712, so address mismatch issues do not occur.

[0280] Subsequently, the non-AP MLD2 2712 can initiate TDLS discovery to STA5 2722 via AP MLD 2702 by generating a follow-up data frame 2752 carrying a TDLS discovery request 2754. Because it knows that STA5 is a non-MLD or traditional STA, it uses the STA MAC address (STA4-M) of one of its affiliated STAs in the TDLS initiator field 2758.

[0281] AP2 2704 of AP MLD 2702 can identify, based on the STA MAC address, that subsequent data frame 2752 is directed to its associated non-AP MLD2 2712 STA4 2714, and forward data frame 2752' to STA5 2722. AP MLD2502 is able to correct the SA field 2755' of data frame 2752' to the MAC address of STA4 (STA4-M) before forwarding data frame 2752' to STA5 2722. Data frame 2752 can still be correctly received by STA5 2722.

[0282] Furthermore, since the SA field 2755' relayed by the AP and the TDLS initiator field 2758' in the link identifier element of the TDLS discovery request frame 2752' are both set to the STA MAC address, no confusion occurs at the receiving peer STA. This effectively solves the first address mismatch problem proposed in IEEE submission (IEEE 802.11-2 / 1692r2) when a non-AP MLD initiates TDLS establishment with a traditional STA, without requiring changes to the RA / TA setting rules or the use of the MLD MAC address in the TDLS initiator or TDLS responder fields.

[0283] In response, STA5 2722 can send a TDLS discovery response action frame 2762 on the direct link (link 2), in which the TA field 2765 and the TDLS responder field 2769 are set to its own STA MAC address. STA5 2722 can also set the RA field to the L2 MAC address of STA4 based on the TDLS initiator field 2758' of the received data frame 2752'.

[0284] Subsequently, STA5 and STA4 can be in a similar manner. Figure 26 The method described herein utilizes TDLS establishment request / response frame exchange to perform TDLS establishment (not shown). Once TDLS establishment has been performed, STA5 2722 and STA4 2714 (non-AP MLD2 2712) can successfully send / receive corresponding data frames 2772 and 2782 to each other on the direct link, because the RA fields 2773 and 2783 of data frames 2772 and 2782 can be correctly set to the STA MAC addresses (STA4-M and STA5-M) accordingly.

[0285] According to this disclosure, when a non-AP MLD resolves the IP address of a legacy STA, even if the address is resolved correctly and even if the non-AP MLD is informed that the target STA is a legacy STA (e.g., due to the lack of an ML indication in the ARP reply), the non-AP MLD cannot definitively know on which link the legacy STA is operating on. When the non-AP MLD initiates TDLS discovery with a legacy STA, there is a possibility that it selects the wrong link and therefore uses the wrong STA MAC address (e.g., STA3-M) in the TDLS Initiator field of the TDLS discovery frame. Therefore, if the legacy STA uses the TDLS Initiator field to set the RA field of a TDLS discovery response frame sent on a direct link, the non-AP MLD2 will not be able to receive the frame.

[0286] Figure 28 A flowchart 2800 is shown illustrating a fourth example of multi-link resolution communication between AP MLD 2802, non-AP MLD 2812, and non-MLD STA 2822 according to a fifth embodiment of the present disclosure.

[0287] In this fourth example, AP MLD 2802 is shown representing a conventional STA (e.g., STA5 2822) resolving ARP requests from a non-AP MLD (e.g., non-AP MLD2 2812).

[0288] STA3 2814, which is not AP MLD2 2812, can initiate an ARP query by generating a first data frame 2832 carrying an ARP request 2834 and sending it to STA5 2822 via AP MLD 2802 on an operating link different from that of STA5 (in this case, link 1 or the 5GHz band). The ARP request 2834 includes a source hardware field 2836 carrying the MAC address of the non-AP MLD2 (STA-MLD2-M) and a destination IP field 2839 carrying the IP address of STA5 (STA5-IP), indicating that the non-AP MLD2 2812 is attempting to resolve the IP address to obtain the corresponding MAC address of STA5 2822.

[0289] Next, AP12804, which receives the first data frame 2832 on the 5GHz link, can identify the requester (i.e., non-AP MLD2 2812) as MLD based on the source hardware field 2836 of the ARP request 2834, and the destination IP address carried in the destination IP field 2839 of the ARP request 2834 matches the IP address of its associated STA5. Therefore, APMLD 2802 can generate a second data frame 2842 carrying an ARP response 2844, and provide the L2 MAC address (STA5-M) of STA5 as its hardware address in the source hardware field 2846 of the ARP response 2844 (keeping the b0 bit of the MAC address 0), and send the second data frame 2842 back to non-AP MLD2 2812.

[0290] The non-AP MLD2 2812, which receives the second data frame 2842 via STA3 2814 on link 1, can process the ARP reply 2844. Because the ML indicator is missing in bit b0, it begins to recognize that the MAC address carried in the source hardware field 2846 is the STA MAC address, not the MLD MAC address. The non-AP MLD2 2812 can update its ARP cache to map the IP address of STA5 (STA5-IP) in the source IP field 2847 to the L2 MAC address of STA5 (STA5-M) in the source hardware field 2846. As a result, the ARP query is resolved.

[0291] Subsequently, the non-AP MLD2 2812 can initiate TDLS discovery via AP MLD 2802 to STA5 2822's subsequent data frame 2852 by generating a TDLS discovery request 2854 using an incorrect link (i.e., a link on which STA5 2822 is not operating). Because it knows that STA5 is a non-MLD or legacy STA, it uses the STA MAC address of STA3 2814 operating on 5 GHz in the TDLS initiator field 2858, but this STA MAC address happens to be an incorrect address (STA3-M).

[0292] AP MLD 2802 can identify that subsequent data frame 2852 is directed to STA5 2822 based on the STA MAC address. It sets the SA field 2855' of data frame 2852 to the correct STA MAC address (STA4-M) of the TDLS initiator STA4 2816 operating on the STA5's operational link, and forwards data frame 2852' to STA5 2822 via AP2 2802 on the correct link (6GHz band). Thus, data frame 2852 is correctly received by STA5 2822.

[0293] In response, STA5 2822 can send a TDLS discovery response action frame 2862 on the direct link (link 2), in which the TA field 2865 and the TDLS responder field 2869 are set to its own STA MAC address, but the RA field 2863 is set to the MAC address of the incorrect link (STA3-M) based on the TDLS initiator field 2858' of the received data frame 2852'. Therefore, data frame 2862 on the direct link between STA5 2822 and STA4 2816 fails due to the incorrect RA.

[0294] To avoid potential mismatches due to crossover issues, the AP MLD can assist the non-AP MLD by ensuring that ARP replies sent on behalf of a legacy / non-MLD STA are always sent on the link on which the legacy / non-MLD STA is operating, provided that the non-AP MLD is also operating on that link. The non-AP MLD is informed that the peer STA is a legacy / non-MLD STA because the data frame carrying the ARP reply lacks a "ML indicator." The non-AP MLD is implicitly informed of the operating link of the legacy / non-MLD STA based on the link on which the ARP reply is received, thus avoiding crossover issues caused by incorrect TDLS initiator addresses.

[0295] Figure 29 A flowchart 2900 is shown illustrating a fifth example of communication between AP MLD 2902, non-AP MLD 2912, and non-MLD STA2922 for multi-link resolution according to a fifth embodiment of the present disclosure.

[0296] In this fifth example, AP MLD 2902 is shown representing a conventional STA (e.g., STA5 2922) resolving an ARP request from a non-AP MLD (e.g., non-AP MLD2 2912).

[0297] STA3 2914, which is not AP MLD2 2912, can initiate an ARP query by generating a first data frame 2932 carrying an ARP request 2934 on an operating link different from that of STA5 (in this case, link 1 or the 5GHz band) and sending it to STA5 2922 via AP MLD 2902. The ARP request 2934 includes a source hardware field 2936 carrying the MAC address of the non-AP MLD2 (STA-MLD2-M) and a destination IP field 2939 carrying the IP address of STA5 (STA5-IP), indicating that the non-AP MLD2 2912 is attempting to resolve the IP address to obtain the corresponding MAC address of STA5 2922.

[0298] Even if ARP request 2934 is received on a link (link 2) that is different from the operating link of a traditional STA, AP MLD 2902, which receives the first data frame 2932, can identify the requester (i.e., non-AP MLD2 2912) as MLD based on the source hardware field 2936 of ARP request 2934, and the destination IP address carried in the destination IP field 2939 of ARP request 2934 matches the IP address of its associated STA5. Therefore, AP MLD 2902 can generate a second data frame 2942 and intentionally send ARP response 2944 back to non-AP MLD22912 via AP2 2906 on the link where the target STA (STA5 2922) operates, and provide the L2 MAC address (STA5-M) of STA5 as its hardware address in the source hardware field 2946 of ARP response 2944.

[0299] The non-AP MLD2 2912, which receives the second data frame 2942 via STA4 2816 on link 2, can process ARP reply 2944. Because the ML indicator is missing in bit b0, it begins to recognize that the MAC address carried in the source hardware field 2946 is the STA MAC address, not the MLD MAC address. The non-AP MLD2 2912 can update its ARP cache to map the IP address of STA5 (STA5-IP) in the source IP field 2947 to the L2 MAC address of STA5 (STA5-M) in the source hardware field 2946. As a result, the ARP query is resolved. Furthermore, the non-AP MLD2 2912 also records link 2 as the operational link for STA5 based on the link in which ARP reply 2944 was received.

[0300] Subsequently, the non-AP MLD2 2912 can initiate TDLS discovery to STA5 2922 via AP MLD 2902 on the correct link (link 2) (i.e., the operational link of STA5) by generating a follow-up data frame 2952 carrying a TDLS discovery request 2954. Since it knows that STA5 is a non-MLD or legacy STA, the correct STA MAC address (STA4-M) of the non-AP MLD 2912 is used as the TDLS initiator field 2958 of the TDLS discovery request 2954 in the follow-up data frame 2952.

[0301] The AP MLD 2902 can identify that subsequent data frame 2952 is directed to STA5 2922 based on the STA MAC address, and forward data frame 2952 to STA5 2922. The AP MLD 2902 sets the SA field 2955' of data frame 2952' to the MAC address of STA4 (STA4-M), and forwards data frame 2952 to STA5 2922 on the correct link. In this way, data frame 2952 can still be correctly received by STA5 2922.

[0302] In response, STA5 2922 can send a TDLS discovery response action frame 2962 on the direct link (link 2), in which the TA field 2965 and the TDLS responder field 2969 are set to its own STA MAC address. STA5 2822 is able to set the correct link MAC address (STA4-M) to the RA field 2863 based on the TDLS initiator field 2958' of the received data frame 2952', and the TDLS discovery response action frame 2962 is correctly received by STA4 2916.

[0303] As a result, STA5 2922 and STA4 2916 of non-AP MLD2 2912 can send / receive corresponding data frames 2972 ​​and 2982 to each other on the direct link, because the RA fields 2973 and 2983 of data frames 2972 ​​and 2982 can be correctly set to the STA MAC addresses (STA5-M and STA4-M) accordingly.

[0304] Figure 30 A flowchart 3000 is shown illustrating a sixth example of a fifth embodiment of the present disclosure, illustrating communication between AP MLD 3002, non-AP MLD 3012, and non-MLD STA 3022 for multi-link resolution.

[0305] The sixth example is Figure 28This is a continuation of the fourth example shown, where the original TDLS discovery request frame is sent on the wrong link with the wrong TDLS initiator address. In this sixth example, an explicit solution to the cross-reference presented in the fifth example of the fifth embodiment of this disclosure is shown by using the MLD address lookup mechanism to discover the operational link of a non-MLD STA, referencing AP MLD 3002, non-AP MLD (e.g., non-AP MLD2 3012), and a traditional STA (e.g., STA5 3022). In this sixth example, the MLD address lookup mechanism is not used to resolve the STA MAC address of the MLD, but rather to discover the operational link of the non-MLD STA. Alternatively, a non-AP MLD may blindly retry the TDLS discovery request on another link if it fails to receive a TDLS discovery response frame.

[0306] Following the APR query and the transmission of subsequent data frames carrying the TDLS discovery request, STA5 3022 can base its analysis on the TDLS initiator field in the TDLS discovery request. Figure 30 (Not shown in the image), a TDLS discovery response action frame carrying an error RA field 3033 (e.g., set to the STA MAC address (STA3-M) of STA3 3014) is sent to STA4 3016 on the direct link. As a result, all frames on the direct link will fail due to the error RA.

[0307] Since the TDLS discovery response frame 3032 was not received from STA5 3022 on the direct link, non-AP MLD2 3012 can infer that the TDLS discovery request frame may have been sent on the wrong link. Non-AP MLD2 3012 can then send an MLD address query request frame 3042 to STA5 3022 via AP2 3004 (non-AP MLD 3002). AP MLD 2902, receiving the MLD address query request frame 3042, can recognize that the MAC address carried in the target MLD MAC address field 3048 of the MLD address query request 3042 matches the MAC address of its associated STA5, indicating that non-AP MLD2 is attempting to resolve the IP address to obtain the corresponding MAC address and operating link of STA5 3022. Therefore, AP MLD 3002 can generate an MLD address query response frame 3052 to provide this information to non-AP MLD2 3012 on behalf of STA5 3022. Specifically, the MLD address query response frame 3052 includes an ML element carrying a single link information field, wherein the value of the link ID subfield 3059a is 2 to indicate that the operating link of the target STA is link 2, and the address field 3059b indicates the MAC address of the target STA, namely, STA5 3022.

[0308] After receiving information about the correct link for sending data frames, non-AP MLD2 can re-initiate TDLS discovery by sending a data frame 3062 carrying a TDLS discovery request 3064 to STA5 3022 on the correct (given) link received via APMLD 3002 in the MLD address query response frame 3052. The correct link (STA MAC address), i.e., STA4-M, is used in the TDLS initiator field 3068 of the TDLS discovery request 3064.

[0309] AP MLD 3002 can identify that data frame 3062 is directed to STA5 3022 based on the STA MAC address in the TDLS responder field 3069, and forward it to STA5 3022. AP MLD 2902 sets the SA field 3065' of data frame 3062' to the MAC address of STA4 (STA4-M) to indicate the source of data frame 3062'. In this way, data frame 2952 is correctly received by STA5 3022 via AP MLD 3002.

[0310] Next, in response, STA5 3022 can send a TDLS discovery response action frame 3072 to STA4 3016 (not AP MLD3012) via the direct link (link 2). STA5 3022 is able to correctly set the MAC address of STA4 in the RA field 3073. Thus, since the RA fields 3073 and 3083 are correctly set to the STA's MAC address, the TDLS discovery response action frame 3072 from STA5 3022 to STA4 3016 on the direct link, and any subsequent data frames 3072, are correctly received by STA4.

[0311] This disclosure states that: (i) the IP address of the MLD is dynamically mapped to either the MLD MAC address or the L2 MAC address of the MLD. If the requesting station is an MLD, the MLD MAC address is returned as the hardware MAC address of the MLD; otherwise, if the requesting station is a non-MLD (EHT or traditional STA), the MAC address of the associated AP / STA operating on the link in which the ARP request or neighbor request is received is returned as the hardware MAC address of the MLD; (ii) Frames sent by the MLD carry an “ML indication” to indicate that they were sent by (or originated from) the MLD; (iii) An MLD address lookup mechanism is proposed to perform the resolution of the MLD MAC address to the L2 MAC address; (iv) Proxy ARP dynamically maps the IP address of the associated station’s MAC address to one of the MLD MAC address or the MLD’s L2 MAC address, depending on whether the requesting station is an MLD or a non-MLD, wherein the proxy ARP also responds to the MLD address lookup request on behalf of the associated non-AP MLD and also sets the “ML indication” in the ARP / ND response; and (v) AP MLD only forwards ARP / ND responses received from the associated MLD in the same BSS that is being operated by the non-MLD STA addressed in the DA.

[0312] Figure 31An example configuration of a communication device 3100 and two communication devices 3102, 3104 attached to the communication device 3100 is shown. According to this disclosure, the communication device 3100 is implemented as an AP MLD, and each of the attached communication devices 3102, 3104 can be implemented as an AP and configured for multi-link address resolution. The communication device 3100 also includes a storage module 3101 for storing its MLD MAC address, a first functional module 3106 for generating and processing MLD address query-related services, and a second functional module 3108 for generating and processing frames for proxy ARP-related services. The communication device 3100 also includes an MLD MAC SAP 3110 for communicating with the Internet layer, which includes an ARP module 3114 and an ICMP module 3116 for generating and processing ARP and ND query frames, respectively. Each of the communication devices 3102, 3104 attached to the communication device provides a link to and / or a distribution system (DS) associated with other external communication devices / equipment and / or distribution systems (DS), and is capable of sending / receiving signals to and from them. Each auxiliary communication device 3102, 3104 includes a MAC layer 3120 and a PHY (physical) layer 3122. The MAC layer includes a storage module 3121 for storing its AP MAC address and an optional AP MAC SAP 3124 for direct communication with the Internet layer for traffic to / from a legacy STA. The PHY layer is connected to a radio transmitter, radio receiver and antenna for sending / receiving signals to / from the corresponding link 3118.

[0313] According to this disclosure, as shown in line 3126, traffic (including ARP and ND messages) from MLD to DS / from DS to MLD is routed via MLD MAC SAP 3110, and as shown in line 3128, traffic (including ARP and ND messages) from non-MLD to DS / from DS to non-MLD is routed via AP MAC SAP 3124. ARP / ND returns the MAC address of the corresponding MAC SAP through which ARP / ND requests are received.

[0314] Figure 32An example configuration of a communication device 3200 and two communication devices 3202 and 3204 attached to the communication device 3200 is shown. According to this disclosure, the communication device 3200 is implemented as a non-AP MLD, and each of the attached communication devices 3202 and 3204 can be implemented as an AP and configured for multi-link address resolution. The communication device 3200 also includes a storage module 3201 for storing its MLD MAC address and a functional module 3206 for generating and processing MLD address query-related services. The communication device 3200 also includes an MLD MAC SAP 3210 for communicating with the Internet layer, which includes an ARP module 3214 and an ICMP module 3216 for generating and processing ARP and ND query frames, respectively. Each of the communication devices 3202 and 3204 attached to the communication device provides a link to other external communication devices / equipment and is capable of sending / receiving signals to / from them. Each auxiliary communication device 3202, 3204 includes a MAC layer 3220 and a PHY (physical) layer 3222. The MAC layer includes a storage module 3221 for storing its STA MAC address and an optional STA MAC SAP 3224 for direct communication with the Internet layer for traffic to / from a legacy STA. The PHY layer is connected to a radio transmitter, radio receiver and antenna for sending / receiving signals to / from the corresponding link 3218.

[0315] According to this disclosure, as shown in line 3226, traffic (including ARP and ND messages) from MLD to DS / from DS to MLD is routed via MLD MAC SAP 3210, and as shown in line 3228, traffic (including ARP and ND messages) from non-MLD to DS / from DS to non-MLD is routed via STA MAC SAP 3224. ARP / ND returns the MAC address of the corresponding MAC SAP through which ARP / ND requests are received.

[0316] This disclosure can be implemented in software, hardware, or software working in conjunction with hardware. Each functional block used in the description of each of the above embodiments can be implemented partially or entirely by an LSI such as an integrated circuit, and each process described in each embodiment can be controlled partially or entirely by the same LSI or a combination of LSIs. An LSI can be formed as a single chip, or it can be formed as a single chip to include some or all of the functional blocks. An LSI can include data inputs and outputs coupled thereto. Depending on the level of integration, the LSI herein can be referred to as an IC, a system LSI, a super LSI, or an ultra-LSI. However, the technology for implementing an integrated circuit is not limited to LSIs and can be implemented using dedicated circuitry, general-purpose processors, or special-purpose processors. Furthermore, FPGAs (Field Programmable Gate Arrays) or reconfigurable processors that are programmable after the LSI is manufactured can be used, wherein the connections and settings of the circuit cells configured within the LSI can be reconfigured. This disclosure can be implemented as digital or analog processing. If future integrated circuit technologies replace LSIs due to advancements in semiconductor technology or other derivative technologies, the functional blocks can be integrated using future integrated circuit technologies. Biotechnology can also be applied.

[0317] This disclosure can be implemented by any type of apparatus, device or system having communication capabilities, which are referred to as communication devices.

[0318] Some non-limiting examples of such communication devices include telephones (e.g., cellular phones, smartphones), tablets, computers, personal computers (PCs) (e.g., laptops, desktops, netbooks), cameras (e.g., digital still / video cameras), digital players (digital audio / video players), wearable devices (e.g., wearable cameras, smartwatches, tracking devices), game consoles, digital book readers, remote health / telemedicine (remote health and medicine) devices, and vehicles that provide communication capabilities (e.g., cars, airplanes, ships) and various combinations thereof.

[0319] Communication devices are not limited to portable or mobile devices, and may also include any kind of non-portable or fixed device, equipment or system, such as smart home devices (e.g., home appliances, lighting, smart meters, control panels), vending machines and any other “thing” in a network of “Internet of Things (IoT)”.

[0320] Communication may include the exchange of data through, for example, cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0321] The communication device may include a controller or sensor coupled to a communication device that performs the communication functions described in this disclosure. For example, the communication device may include a controller or sensor that generates control signals or data signals used by a communication means performing the communication functions of the communication device.

[0322] The communication device may also include infrastructure such as base stations, access points, and any other means, equipment, or systems that communicate with or control such devices as those in the non-limiting examples above.

[0323] A non-limiting example of a station could be one of a first plurality of stations attached to a multi-link station logical entity (i.e., such as an MLD), wherein, as part of the first plurality of stations attached to the multi-link station logical entity, the stations of the first plurality of stations share a common media access control (MAC) data service interface at the upper layer, wherein the common MAC data service interface is associated with a common MAC address or traffic identifier (TID).

[0324] Therefore, it can be seen that this embodiment provides communication devices and methods for operation on multiple links in order to fully realize the throughput gain of multi-link communication, especially for multi-link secure retransmission.

[0325] Although exemplary embodiments have been presented in the foregoing detailed description of these embodiments, it should be understood that numerous variations exist. It should also be understood that the exemplary embodiments are examples and are not intended to limit the scope, applicability, operation, or configuration of this disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient roadmap for implementing the exemplary embodiments, and it should be understood that various changes can be made to the steps and methods of operation described in the exemplary embodiments, as well as the functionality and arrangement of the modules and structures of the device described in the exemplary embodiments, without departing from the scope of the subject matter set forth in the appended claims.

[0326] According to this disclosure, the following examples have been shown:

[0327] 1. A communication device attached to a plurality of communication devices of a first multi-link device (MLD), the communication device comprising:

[0328] The receiver receives a first data frame carrying an address resolution request from the requesting communication device. The address resolution request carries the Internet Protocol IP address of the first MLD.

[0329] The circuit determines whether the requesting communication device is attached to a second MLD; and generates a second data frame carrying an address resolution response, which carries the Media Access Control (MAC) address of the communication device in response to determining that the requesting communication device is not attached to the second MLD, or carries the MLD MAC address of the first MLD in response to determining that the requesting communication device is attached to the second MLD.

[0330] 2. According to the communication device of Example 1, the address resolution request is one of the Address Resolution Protocol (ARP) request packets and the neighbor request message; and the address resolution response is one of the ARP response packets and the neighbor advertisement message.

[0331] 3. The communication device according to Example 1, wherein a first data frame carries an indication of whether the communication device is attached to a second MLD, and the determination is based on the indication; and in response to the determination, a second data frame carries an indication of whether the communication device is attached to a first MLD.

[0332] 4. The communication apparatus according to Example 3, wherein the indication is carried in the protocol version subfield of the frame control field of the first data frame and the second data frame, respectively.

[0333] 5. The communication device according to Example 3, wherein the indication is carried in the least significant bits of the MAC address associated with the requesting communication device carried in the first data frame and the second data frame.

[0334] 6. The communication apparatus according to Example 1, wherein the receiver further receives an MLD address query request frame carrying the MLD MAC address of the first MLD; and the circuitry is further configured to:

[0335] Generate an MLD address query response frame, which carries the MAC address and the identifier of the operating link for each of the multiple communication devices.

[0336] 7. The communication device according to Example 6, wherein the MLD address query request frame and the MLD address query response frame are pre-configured action frames or are encapsulated in pre-configured data frames.

[0337] 8. The communication device according to Example 7, wherein the MLD address query request frame is received from another communication device that is attached to or not attached to the MLD.

[0338] 9. According to the communication device of Example 3, the circuit is further configured as follows:

[0339] Set the least significant bit of at least one of the following: (i) the sender address field in the address resolution request, including the MAC address associated with the requesting communication device to carry an indication, and (ii) the sender address field in the address resolution response, including the MLD MAC address of the first MLD to carry an indication.

[0340] 10. The communication device according to Example 1, wherein, in response to determining that the communication device is attached to the second MLD, the circuitry is further configured to:

[0341] The least significant bit of the MAC address of the TDLS initiator communication device is set in the TDLS request frame sent to the TDLS responder communication device that establishes the TDLS direct link in the tunnel. The TDLS initiator communication device is one of the communication devices and the requesting communication device, and the TDLS responder communication device is the remaining one of the communication devices and the requesting communication device. The least significant bit indicates the association between the TDLS initiator communication and the MLD.

[0342] 11. The communication device according to Example 1, wherein the communication device is an access point (AP) and the first MLD is an APMLD.

[0343] 12. The communication apparatus according to Example 11, wherein, in response to determining that the requesting communication apparatus is not attached to the second MLD, and the destination address field of the first data frame carries either a broadcast address or an MLD MAC address associated with the AP MLD, the circuitry is further configured to:

[0344] The first data frame is forwarded only to one or more communication devices in the basic service set, in which the requesting communication device is associated with one or more communication devices.

[0345] 13. The communication apparatus according to Example 11, wherein, in response to determining that the requesting communication apparatus is associated with a second MLD, and the destination field of the first data frame carries the MAC address of another communication apparatus not attached to the MLD but associated with one of a plurality of communication apparatuses attached to the AP MLD, the circuitry is further configured to:

[0346] The first data frame is forwarded only to one or more communication devices in the basic service set, in which the requesting communication device is associated with one or more communication devices.

[0347] 14. The communication device according to Example 1, wherein the communication device is a station and the first MLD is a non-AP MLD.

[0348] 15. An AP among a plurality of APs attached to an access point AP MLD, the AP comprising:

[0349] The receiver receives a first data frame carrying an address resolution request from the requesting communication device. The address resolution request carries the IP address of a first MLD associated with the AP MLD. The first MLD includes multiple communication devices.

[0350] The circuit determines whether the requesting communication device is attached to a second MLD associated with the AP MLD; and generates a second data frame carrying an address resolution response, in response to determining that the requesting communication device is not attached to the second MLD, the address resolution response carrying the MAC address of a communication device among a plurality of communication devices attached to the first MLD, or in response to determining that the requesting communication device is attached to the second MLD, the address resolution response carrying the MLD MAC address of the first MLD.

[0351] 16. According to the AP in Example 15, the address resolution request is one of the ARP request packets and the neighbor request message; and the address resolution response is one of the ARP response packets and the neighbor advertisement message.

[0352] 17. According to the AP of Example 15, wherein the receiver also receives an MLD address query request frame carrying the MLD MAC address of the first MLD; and the circuit is further configured to:

[0353] An MLD address query response frame is generated, which carries the MAC address and the identifier of the operating link of each of the plurality of communication devices attached to the first MLD.

[0354] 18. According to the AP of Example 15, wherein the receiver also receives an MLD address query request frame carrying the MAC address of the associated communication device; and the circuit is further configured to:

[0355] Generate an MLD address query response frame, which carries the MAC address of the associated communication device and the identifier of the operating link.

[0356] 19. According to the AP of Example 15, wherein, in response to determining that the requesting communication device is not attached to the second MLD, and the destination address field of the first data frame carries either a broadcast address or an MLD MAC address of an MLD associated with the AP MLD that includes the first MLD, the circuitry is further configured to:

[0357] The first data frame is forwarded only to one or more communication devices in the basic service set, in which the requesting communication device is associated with one or more communication devices.

[0358] 20. According to the AP of Example 15, wherein, in response to determining that the requesting communication device is associated with a second MLD, and the destination field of the first data frame carries the MAC address of another communication device not attached to the MLD but associated with one of the APs attached to the AP MLD, the circuitry is further configured to:

[0359] The first data frame is forwarded only to one or more communication devices in the basic service set, in which the requesting communication device is associated with one or more communication devices.

[0360] 21. According to the AP in Example 15, the circuit is further configured as follows:

[0361] The least significant bit of the sender address field in the address resolution response, which includes the MLD MAC address of the first MLD, is set to indicate that the communication device is associated with the first MLD.

[0362] 22. According to the AP in Example 19 or 30, the circuit is further configured to:

[0363] The least significant bit of the sender address field is set. The sender address field includes the MAC address associated with the requesting communication device carried in the address resolution request carried in the first data frame. The least significant bit indicates whether the requesting communication device is associated with the second MLD.

[0364] 23. A communication method, comprising:

[0365] Receive a first data frame carrying an address resolution request from the requesting communication device. The address resolution request carries the IP address of the first MLD.

[0366] Determine whether the requesting communication device is attached to the second MLD; and

[0367] A second data frame carrying an address resolution response is generated in response to determining that the requesting communication device is not attached to the second MLD. The address resolution response carries the MAC address of the communication device among a plurality of communication devices attached to the first MLD. Alternatively, in response to determining that the requesting communication device is attached to the second MLD, the address resolution response carries the MLD MAC address of the first MLD.

Claims

1. A communication device attached to a plurality of communication devices of a first multi-link device (MLD), the communication device comprising: The receiver receives a first data frame carrying an address resolution request from the requesting communication device, the address resolution request carrying the Internet Protocol IP address of the first MLD; The circuit determines whether the requesting communication device is attached to the second MLD; And generate a second data frame carrying an address resolution response, in response to determining that the requesting communication device is not attached to the second MLD, the address resolution response carrying the media access control (MAC) address of the communication device, or in response to determining that the requesting communication device is attached to the second MLD, the address resolution response carrying the MLD MAC address of the first MLD.

2. The communication device according to claim 1, wherein, The address resolution request is one of the Address Resolution Protocol (ARP) request packets and the Neighbor Request message; and the address resolution response is one of the ARP response packets and the Neighbor Advertisement message.

3. The communication device according to claim 1, wherein, The first data frame carries an indication of whether the requesting communication device is attached to the second MLD, and the determination is based on the indication; In response to the determination, the second data frame carries an indication of whether the communication device is attached to the first MLD.

4. The communication device according to claim 3, wherein, The indication is carried in the protocol version subfield of the frame control field of the first data frame and the second data frame, respectively.

5. The communication device according to claim 3, wherein, The indication is carried in the least significant bits of the MAC address associated with the requesting communication device, which is carried in the first and second data frames.

6. The communication device according to claim 1, wherein, The receiver also receives an MLD address query request frame carrying the MLD MAC address of the first MLD; and the circuit is further configured to: An MLD address query response frame is generated, the MLD address query response frame carrying the MAC address and the identifier of the operating link of each of the plurality of communication devices.

7. The communication device according to claim 6, wherein, The MLD address query request frame and the MLD address query response frame are pre-configured action frames or encapsulated in pre-configured data frames.

8. The communication device according to claim 7, wherein, The MLD address query request frame is received from another communication device, which may or may not be attached to the MLD.

9. The communication device according to claim 3, wherein, The circuit is also configured to: The least significant bit of at least one of the following is set: (i) the sender address field in the address resolution request, the sender address field including a MAC address associated with the requesting communication device to carry the indication, and (ii) the sender address field in the address resolution response, the sender address field including the MLD MAC address of the first MLD to carry the indication.

10. The communication device according to claim 1, wherein, In response to determining that the requesting communication device is attached to the second MLD, the circuit is further configured to: The least significant bit of the MAC address of the TDLS initiator communication device is set in the TDLS request frame sent to the TDLS responder communication device that establishes the tunnel direct link. The TDLS initiator communication device is one of the communication device and the requesting communication device, and the TDLS responder communication device is the remaining one of the communication device and the requesting communication device. The least significant bit indicates the association between the TDLS initiator communication and the MLD.

11. The communication device according to claim 1, wherein, The communication device is an access point (AP), and the first MLD is an AP MLD.

12. The communication device according to claim 1, wherein, The communication device is a station, and the first MLD is a non-AP MLD.

13. An AP among a plurality of APs attached to an access point AP MLD, the AP comprising: The receiver receives a first data frame carrying an address resolution request from a requesting communication device. The address resolution request carries the IP address of a first MLD associated with the AP MLD, and the first MLD includes multiple communication devices. The circuit determines whether the requesting communication device is attached to a second MLD associated with the AP MLD; And generate a second data frame carrying an address resolution response, in response to determining that the requesting communication device is not attached to the second MLD, the address resolution response carrying the MAC address of the communication device among the plurality of communication devices attached to the first MLD, or in response to determining that the requesting communication device is attached to the second MLD, the address resolution response carrying the MLD MAC address of the first MLD.

14. The AP according to claim 13, wherein, The address resolution request is one of the Address Resolution Protocol (ARP) request packets and the Neighbor Request message; and the address resolution response is one of the ARP response packets and the Neighbor Advertisement message.

15. The AP according to claim 13, wherein, The receiver also receives an MLD address query request frame carrying the MLD MAC address of the first MLD; and the circuit is further configured to: An MLD address query response frame is generated, the MLD address query response frame carrying the MAC address and the identifier of the operating link of each of the plurality of communication devices attached to the first MLD.

16. The AP according to claim 13, wherein, The receiver also receives an MLD address query request frame carrying the MAC address of the associated communication device; and the circuit is further configured to: An MLD address query response frame is generated, which carries the MAC address of the associated communication device and the identifier of the operating link.

17. The AP according to claim 13, wherein, In response to determining that the requesting communication device is not attached to the second MLD, and that the destination address field of the first data frame carries either a broadcast address or the MLD MAC address of the first MLD associated with the AP MLD, the circuit is further configured to: The first data frame is forwarded only to one or more communication devices in a basic service set, where the requesting communication device is associated with the one or more communication devices.

18. The AP according to claim 13, wherein, In response to determining that the requesting communication device is associated with the second MLD, and that the destination address field of the first data frame carries the MAC address of another communication device not attached to the MLD but associated with one of the APs attached to the AP MLD, the circuit is further configured to: The first data frame is forwarded only to one or more communication devices in a basic service set, where the requesting communication device is associated with the one or more communication devices.

19. The AP according to claim 13, wherein, The circuit is also configured to: The least significant bit of the sender address field in the address resolution response, which includes the MAC address of the first MLD, is set to indicate that the communication device is associated with the first MLD.

20. A communication method, comprising: Receive a first data frame carrying an address resolution request from the requesting communication device, the address resolution request carrying the IP address of the first MLD; Determine whether the requesting communication device is attached to the second MLD; as well as A second data frame carrying an address resolution response is generated in response to determining that the requesting communication device is not attached to the second MLD, wherein the address resolution response carries the MAC address of a communication device among a plurality of communication devices attached to the first MLD, or in response to determining that the requesting communication device is attached to the second MLD, wherein the address resolution response carries the MLD MAC address of the first MLD.

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