Communication device and communication method for multilink address resolution

Abstract

To facilitate the provision of communication devices and communication methods for multilink address resolution. [Solution] A requesting communication device that makes an ARP request to an AP MLD including multiple cooperating APs includes a transmitting unit that sends an ARP request to the AP MLD including the IP address to be resolved, and a receiving circuit that, if the target IP address corresponds to a non-AP MLD, receives an ARP response that includes the MLD MAC address of the non-AP MLD as the source MAC address, and receives a frame that includes the MLD MAC address of the requesting communication device as the receiving address directly from the non-AP MLD via the link.

Description

Technical Field

[0001] This embodiment generally relates to a communication device, and more specifically, to a method and apparatus for multi-link address resolution.

Background Art

[0002] In today's world, it is expected that communication devices will operate wirelessly with the same performance as wired computing devices. For example, a user expects to be able to seamlessly view a high-resolution movie streamed to the user's wireless communication device. This presents challenges for the communication device as well as the access point to which the communication device wirelessly connects.

[0003] The Institute of Electrical and Electronics Engineers (IEEE) 802.11 group recently formed an 802.11 Task Group (TG) to address these challenges. Multi-link operation in the 2.4 GHz, 5 GHz, and 6 GHz frequency bands has been identified as a key candidate technology for such communication. Multi-channel aggregation across multiple links is a natural way to improve the throughput of communication data by several times.

[0004] To enable such multi-link operation between an access point (AP) multi-link device (MLD) and a non-AP MLD, a multi-link setup may be performed through one of the supported links to establish an association with the affiliated station (STA) in one or more links.

[0005] However, in the context of MLD, there has been no discussion until now regarding multilink address resolution that supports legacy STA to resolve the link layer address (e.g., MAC address) of a peer device from a given internet layer address (e.g., IP address).

[0006] Therefore, there is a need for communication devices and communication methods that can solve the aforementioned problems. Furthermore, other desirable features and characteristics will become apparent from the following detailed description and the attached claims, in conjunction with the attached drawings and this background art of the present disclosure. [Overview of the project] [Means for solving the problem]

[0007] Non-limiting and exemplary embodiments facilitate the provision of communication devices and communication methods for multilink address resolution.

[0008] In a first embodiment, the Disclosure provides one of a plurality of communication devices coordinating with a first multilink device (MLD), the communication device comprising: a receiver that, in operation, receives a first data frame from a requesting communication device, the address resolution request including the Internet Protocol (IP) address of the first MLD; and a circuit that, in operation, determines whether the requesting communication device is coordinating with a second MLD and generates a second data frame including an address resolution response, the address resolution response including, in response to a determination that the requesting communication device is not coordinating with the second MLD, the media access control (MAC) address of the communication device, or in response to a determination that the requesting communication device is coordinating with the second MLD, the MLD MAC address of the first MLD.

[0009] In a second aspect, the Disclosure provides one of a plurality of access points (APs) that are linked to an AP MLD, the AP comprising: a receiver that, during operation, receives a first data frame from a requesting communication device, the address resolution request comprising the IP address of a first MLD associated with the AP MLD, the first MLD comprising a plurality of communication devices; and a circuit that, during operation, determines whether the requesting communication device is linked to a second MLD associated with the AP MLD, and generates a second data frame comprising an address resolution response, the address resolution response comprising, in response to the determination that the requesting communication device is not linked to the second MLD, the MAC address of one of the plurality of communication devices linked to the first MLD, or in response to the determination that the requesting communication device is linked to the second MLD, the MLD MAC address of the first MLD.

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

[0011] Any additional benefits and advantages of the disclosed embodiments will become apparent from the specification and drawings. Such benefits and / or advantages may be obtained individually from the various embodiments and features of the specification and drawings, and it is not necessary for all of them to be provided in order to obtain one or more of such benefits and / or advantages.

[0012] The attached figures, in which similar reference figures refer to identical or functionally similar elements across separate views, are incorporated herein, together with the following detailed description, to form part of this specification, illustrating various embodiments and serving to illustrate various principles and advantages according to these embodiments. [Brief explanation of the drawing]

[0013] [Figure 1] This diagram shows a schematic representation of the proxy ARP function of an access point (AP). [Figure 2] The configuration of MLD is shown. [Figure 3] This schematic diagram shows the direct link communication between an AP (Access Point) of an AP-MLD (Application Programming Device) and a STA (Staff Unit) that is either connected to or not connected to a non-AP MLD (Application Programming Device). [Figure 4] An example of the configuration of a communication device according to this disclosure is shown. The communication device may be implemented as an access point (AP) and a station (STA) and configured for multilink address resolution according to this disclosure. [Figure 5] A flowchart 500 illustrating the communication method described herein is shown. [Figure 6A] A schematic diagram is shown illustrating an example configuration of communication between the AP MLD for multilink address resolution and the network interface layer of the AP MLD with its Internet layer, according to the first embodiment of this disclosure. [Figure 6B] A schematic diagram is shown illustrating an example of a configuration for communication between a non-AP MLD and its Internet layer for multilink address resolution, according to the first embodiment of this disclosure. [Figure 7] A flowchart illustrating communication between an AP MLD and a non-AP MLD for multilink address resolution according to the first embodiment of this disclosure is shown. [Figure 8] A flowchart illustrating communication between two non-AP MLDs via an AP MLD for multilink address resolution, according to a first embodiment of this disclosure, is shown. [Figure 9]A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution is shown according to a first embodiment of this disclosure. [Figure 10] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution is shown according to a first embodiment of this disclosure. [Figure 11A] A schematic diagram is shown illustrating an example of the configuration of communication between the AP-MLD and the network interface layer of the AP-MLD with the Internet layer for multilink address resolution, according to a second embodiment of this disclosure. [Figure 11B] A schematic diagram is shown illustrating an example configuration of communication between non-AP-MLD and non-AP-MLD network interface layers with their Internet layer for multilink address resolution, according to a second embodiment of this disclosure. [Figure 12] An example of a data frame format according to a second embodiment of this disclosure is shown. [Figure 13] A flowchart illustrating communication between an AP MLD and a non-MLD STA for multilink address resolution according to a second embodiment of this disclosure is shown. [Figure 14] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution, according to a second embodiment of this disclosure, is shown. [Figure 15] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution, according to a second embodiment of this disclosure, is shown. [Figure 16] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution, according to a second embodiment of this disclosure, is shown. [Figure 17] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution, according to a second embodiment of this disclosure, is shown. [Figure 18] A flowchart showing communication between non-AP MLDs via AP MLD for multi-link address resolution according to a third embodiment of the present disclosure is shown. [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. [Figure 20] An example format of an Ethertype 89-0d data frame used to include an MLD address query frame according to a third embodiment of the present disclosure is shown. [Figure 21] An example architecture of the MAC address of a STA or MLD according to a fourth embodiment of the present disclosure is shown. [Figure 22] A flowchart showing communication between two non-AP MLDs via AP MLD for multi-link address resolution according to a fourth embodiment of the present disclosure is shown. [Figure 23] A flowchart showing communication between a non-AP MLD and a non-MLD STA via AP MLD for multi-link address resolution according to a fourth embodiment of the present disclosure is shown. [Figure 24A] A flowchart showing 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. [Figure 24B] A flowchart showing 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. [Figure 25] A flowchart showing communication between a non-AP MLD and a non-MLD STA via AP MLD for multi-link address resolution according to a fifth embodiment of the present disclosure is shown. [Figure 26] A flowchart showing communication between two non-AP MLDs via AP MLD for multi-link address resolution according to a fifth embodiment of the present disclosure is shown. [Figure 27]A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution is shown according to a fifth embodiment of this disclosure. [Figure 28] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution is shown according to a fifth embodiment of this disclosure. [Figure 29] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution is shown according to a fifth embodiment of this disclosure. [Figure 30] A flowchart illustrating communication between a non-AP MLD and a non-MLD STA via an AP MLD for multilink address resolution is shown according to a fifth embodiment of this disclosure. [Figure 31] An example configuration of a communication device and two communication devices cooperating with the communication device is shown. The communication device may be implemented as an AP MLD, and each of the cooperating communication devices may be implemented as an AP configured for multilink address resolution according to this disclosure. [Figure 32] An example configuration of a communication device and two communication devices cooperating with the communication device is shown. The communication device may be implemented as a non-AP MLD, and each of the cooperating communication devices may be implemented as an STA configured for multilink address resolution according to this disclosure. [Modes for carrying out the invention]

[0014] Those skilled in the art will notice that the elements in the figures are shown for conciseness and clarity and are not necessarily drawn to scale. For example, the dimensions of some elements in explanatory diagrams, block diagrams, or flowcharts may be exaggerated relative to others to aid in the accurate understanding of this embodiment.

[0015] The following detailed description is essentially illustrative and is not intended to limit the embodiments or the uses and applications of the embodiments. Furthermore, it is not bound by the prior background art or any theory presented in this detailed description. In addition, other desirable features and characteristics will become apparent from the following detailed description and the appended claims when considered together with the accompanying drawings and this background art of the disclosure.

[0016] In the context of IEEE 802.11 (Wi-Fi) technology, a station, often referred to synonymously as an STA, is a communication device capable of using the 802.11 protocol. 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 a wireless medium (WM).

[0017] For example, an STA may be a laptop, a desktop personal computer (PC), a personal digital assistant (PDA), an access point in a wireless local area network (WLAN), or a Wi-Fi phone. An STA may be fixed or mobile. In a WLAN environment, the terms "STA," "wireless client," "user," "user device," and "node" are often used synonymously.

[0018] Similarly, an AP (Access Point), which can be referred to synonymously with a Wireless Access Point (WAP) in the context of IEEE 802.11 (Wi-Fi) technology, is a communication device that allows a STA (Standalone Device) to connect to a wired network in a WLAN. APs typically connect to a router (via a wired network) as standalone devices, but they can also be integrated with or employed within a router.

[0019] As mentioned above, an STA within a WLAN may function as an AP on different occasions, and vice versa. This is because a communication device in the context of IEEE 802.11 (Wi-Fi) technology may include both STA and AP hardware components. In this way, the communication device may switch between STA mode and AP mode based on the actual WLAN conditions and / or requirements.

[0020] The Address Resolution Protocol (ARP) is used to discover a peer device's link-layer address (e.g., MAC address) when its internet-layer address (e.g., IP address) is known. Each device maintains a temporary "ARP cache" of the mapping between the discovered IPv4 address and MAC address. The following steps are performed in ARP: 1. Source device checks cache: The source device will first check its cache to determine if it already has a resolution for the destination device. If it does, it can skip to the final step of this process, step #9. 2. The source device generates an ARP request message: The source device generates an ARP request message. It places its own data link layer address as the source hardware address (SHA) and its own IP address as the source protocol address (SPA). The source device fills in the destination IP address as the protocol address. (It must leave the target hardware address blank because that's what it's trying to determine!) 3. The source device broadcasts the ARP request message: The source broadcasts the ARP request message on the local network. 4. Local devices process the ARP request message. The message is received by each device on the local network. Once processed, each device searches for a match on the target protocol address. Those that do not find a match will drop the message and take no further action. 5. The destination device generates an ARP response message (unicast): One device whose IP address matches the content of the message's target protocol address will generate an ARP response message. It takes the source hardware address and source protocol address fields from the ARP request message and uses these as the target hardware address and target protocol address values ​​for the response. The device then fills in its own Layer 2 address as the source hardware address and its IP address as the source protocol address. 6. The destination device updates its ARP cache: If the source needs to send an IP datagram to the destination now, the destination will naturally need to send a response to the source soon (after all, most communication on a network is bidirectional). As an optimization, the destination device will then 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 having to perform an unnecessary resolution cycle later. This is sometimes called an opportunistic ARP cache update. 7. The destination device sends an ARP response message: The destination device sends an ARP response message. This response does not need to be broadcast, however, so it is sent unicast to the source device. 8. Source device processes ARP response message: The source device processes the response from the destination. It stores the source hardware address as the destination's Layer 2 address to use when sending its IP datagram. 9. The source device updates its ARP cache: The source device uses the source protocol address and source hardware address to update its ARP cache for future use when sending to this device.

[0021] An ARP probe is an ARP request constructed using an SPA with all zeros. Before beginning to use an IPv4 address (whether received through manual configuration, DHCP, or some other means), a host implementing this specification must test whether that address is already in use by broadcasting an ARP probe packet. The target IP address is set to the IP address being probed. If an ARP response is received, that IP address is already in use by another device.

[0022] Neighbor Discovery (ND) may be used to achieve results similar to ARP, except for IPv6 address and MAC address mapping. ND messages are included within ICMP packets.

[0023] Address resolution in IPv6 is also 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 tracks this information about its neighbors. When a source device needs to send an IPv6 datagram to a neighbor on the local network but does not have its hardware address (e.g., MAC address), the source device initiates the address resolution process.

[0024] For example, device A is the soliciting device attempting to send to device B. Instead of sending an ARP request message (Internet Control Message Protocol (ICMP) type 135), device A generates an ND neighbor solicitation message. If the underlying data link protocol supports multicasting, as Ethernet does, the neighbor solicitation message is not broadcast. Instead, it is sent to the soliciting node address of the device whose IPv6 address we are trying to resolve. Device A does not broadcast the message, but instead multicasts it to the soliciting node multicast address of device B. The ND neighbor solicitation message may have an ICMP type of 135, the IP address of device B (the device to be resolved) in the target address field, and the source, i.e., the L2 address of device A (e.g., MAC address).

[0025] Device B will receive the ND Neighbor Solicitation message and respond to Device A with a Neighbor Advertisement message (ICMP type=136) (unicast). This is similar to an ARP response / response frame and tells Device A its physical address. Device A then adds Device B's information to its neighbor cache. For efficiency, mutual resolution is supported, as in IPv4 address resolution. This is done by assuming that Device A knows its own Layer 2 (L2) address and having Device A include it in the Neighbor Solicitation message. Device B will record this along with A's IP address in its neighbor cache.

[0026] A solicited node multicast address is a special mapping that each device on a multicast-enabled network creates from its unicast address. While solicited node addresses are not unique to each IPv6 address, the probability of any two neighbors on a given network having the same address is small. Each device receiving a multicast neighbor solicitation message must also check to ensure that it is the device whose address the source is trying to resolve. (This is similar to how multicast is handled in IPv4, where a single multicast MAC address can potentially be shared by 32 different IP addresses.) In addition, the proxy ARP function is a discretionary wireless network management (WNM) function that allows an AP to respond to ARP requests (IPv4) or neighbor solicitation messages (IPv6) on behalf of the associated STA, and the AP maintains a hardware address (e.g., MAC address) for each associated station, corresponding to an Internet address (e.g., Internet Protocol (IP) address).

[0027] Figure 1 shows a schematic diagram 100 illustrating the proxy ARP function of access point (AP) 102. AP 102 receives an ARP request from one associated STA (e.g., STA1 104) or from a distribution system (DS) 106, along with 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 the other associated STA (e.g., STA2 108), upon receiving the ARP request packet, AP 102 generates an ARP response packet, inserting the MAC address of the other associated STA (e.g., STA2 108) as the source MAC address within 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 solicitation message, AP102 shall respond with a neighbor advertisement message (IETF RFC (Internet Engineering Task Force Request for Comments) 4861, Section 4.4) that includes the MAC address of the other associated STA (e.g., STA2 108) as the source MAC address, on behalf of the other associated STA (e.g., STA2 108).

[0028] ARP request packets and neighbor solicitation messages are typically broadcast across the entire Layer 2 (L2) domain. Using proxy ARP functionality has the advantage of reducing the number of broadcast frames in the basic service set (BSS).

[0029] In particular, address mismatch issues arise in tunneled direct link setup (TDLS) and during TDLS direct link communication, stemming from assumptions about how ARP / ND operates on MLD. According to the IEEE 802.11 submission (IEEE 802.11-2 / 1692r2), the following solutions are proposed to address address mismatch issues in TDLS setup and TDLS direct path communication: • For frames sent directly to the TDLS peer STA, set the transmitter address (TA) field to the MAC address of the non-AP MLD. • Use the MLD MAC address within the link identifier element, and • Use the MLD MAC address during the TDLS PeerKey (TPK) handshake.

[0030] Figure 2 shows a configuration of the MLD200. According to the 802.11be document 0.3(D0.3) specification, a multilink device (MLD) (e.g., AP MLD200) is defined as a device having one or more interconnected APs (or STAs) (e.g., AP1 202 and AP2 204) and a single MAC SAP206 to logical link control (LLC) including one MAC data service. The value of the Address 2 (Transmitted Address (TA)) field in the MAC header of a frame sent wirelessly by an AP shall be the MAC address of the transmitting AP (e.g., AP1 202 and AP2 204) that is working with the MLD200 corresponding to that link (e.g., Link 1 208, Link 2 210), excluding the individual / group bits, which are set to 1 when the TA field value is a bandwidth signaling TA and to 0 otherwise. Similarly, the value of the Address 1 (Recipient Address (RA)) field in the MAC header of an individually addressed frame sent wirelessly to an AP shall be the MAC address of the receiving AP (e.g., AP1 202 and AP2 204) that is working with the MLD corresponding to that link (e.g., Link 1 208, Link 2 210).

[0031] However, the above definition / addressing rules are for EHT MLD. However, EHT APs are also high-efficiency (HE) / very high-throughput (VHT) / high-throughput (HT) APs and need to support legacy STAs (HE / VHT / HT STAs). Legacy STAs do not understand the concept of MLD MAC addresses. Instead, they will only recognize the BSSID (i.e., L2 MAC address) of the AP they are associated with. This may also be true for non-MLD EHT STAs, which are EHT STAs that do not work with MLD.

[0032] Figure 3 shows a schematic diagram 300 illustrating the communication between AP304 and 306, which are linked to AP-MLD302, and STA324 and 326, which are linked to non-MLD STA342 and non-AP MLD322. Each MLD, i.e., AP MLD302 or non-AP MLD322, has a single MAC SAP308, 328, and if MAC SAP308, 328 is associated with their respective MLD MAC addresses 310, 330, then their IP addresses will be mapped accordingly to the MLD MAC addresses. Here, it is assumed that non-AP MLD322 is associated with AP MLD302 and non-MLD STA342 is associated with AP306.

[0033] In other words, AP304 and 306 of AP MLD302 may communicate directly with STA324 and 326 of non-AP MLD322 via link 1 350 and link 2 352, respectively, while AP2 306 may also communicate directly with legacy STA342 via link 2 352. ARP / ND may 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 AP. However, since the IP address included in the ARP / ND query will be mapped to the MLD MAC address, only the MLD MAC address will be returned by default for all ARP / ND queries, and the AP or STA MAC address will not be returned. In this way, the MLD MAC addresses will be shown in the RA field of frames transmitted between STA326 and 342 over the direct link, but the STA may, as it expects those STA MAC addresses to be shown in the RA field, confirm that they are not the intended recipients of that frame, and as a result may drop the frames transmitted over the direct link.

[0034] 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. In the various embodiments described below, the communication devices and methods aim to address how an MLD should perform ARP from a legacy STA and handle address resolution.

[0035] In various embodiments of this disclosure, a multilink device (MLD) may refer to a device operating in two or more frequency bands or links (2.4 GHz, 5 GHz, or 6 GHz). An MLD may comprise two or more communication devices corresponding to two or more links, each operating in a specific frequency band or link. For brevity, each link of an MLD as shown in this disclosure relates to one of many communication devices that work with that MLD, primarily configured to operate in that specific frequency band, in order to send and receive signals to and from another communication device that does not work with that MLD, but also operates in that specific frequency band (2.4 GHz, 5 GHz, or 6 GHz).

[0036] In various embodiments of this disclosure, a non-MLD STA may refer to a legacy (HE / VHT / HT) STA or EHT STA that does not interact with an MLD. Similarly, a non-MLD AP may refer to an EHT AP that does not interact with an MLD.

[0037] In various embodiments of this disclosure, the term “L2 MAC address” refers to the MAC address of a transmitting or receiving STA or AP, while the term “MLD MAC address” refers to the MAC address representing an MLD. For brevity, the letter “M” may be added to the device name (e.g., STA, AP, or MLD) to represent the MAC address of a device. For example, the MLD MAC addresses of an AP MLD and a non-AP MLD would be 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 would be represented as “STA-MLD1-M” and “STA-MLD2-M,” respectively. Similarly, the MAC addresses of an AP and an STA would be 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.

[0038] In this disclosure, similar notation applies to IP addresses. In particular, the letters "IP" are added to the device name (e.g., STA, AP, or MLD) to represent the IP address of a device. 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 there are two non-AP MLDs named "non-AP MLD1" and "non-AP MLD2," their IP addresses would be represented as "STA-MLD1-IP" and "STA-MLD2-IP," respectively. Similarly, the IP addresses of APs and STAs (whether or not they are associated with an MLD) are represented as "AP-IP" and "STA-IP," respectively. When there are two APs named "AP1," "AP2," "STA1," and "STA2," and two STAs, their IP addresses would be represented as "AP1-IP," "AP2-IP," "STA1-IP," and "STA2-IP," respectively.

[0039] In various embodiments of this disclosure, data frames may be used to resolve ARP / ND queries and exchanged between the STA and AP. The data frame may comprise a Receiver Address (RA) field, a Transmitter Address (TA) field, a Destination Address (DA) field, and / or a Source Address (SA) field. The RA field specifies the MAC address of the immediate recipient to which the data frame is being sent. The TA field specifies the MAC address of the immediate sender to which the data frame is being sent. The DA field specifies the MAC address of the destination of the data frame. The SA field specifies the MAC address of the original source of the data frame.

[0040] To resolve an ARP query, the data frame may further include an ARP message (ARP request or ARP response) having a source hardware (Src.Hw) field, a source IP (Src.IP) field, a target hardware (Hw) field, and a target IP field. The source hardware field specifies the MAC address of the sender of the message. The source IP field specifies the IP address of the sender of the message. The target hardware field specifies the MAC address of the receiver to which the message is being sent. The target IP field specifies the IP address of the receiver to which the message is being sent.

[0041] To resolve an ND query, the dataframe may further contain ND messages (neighbor solicitation messages or neighbor advertisement messages). A neighbor solicitation message has a type field with a value of 135, a target address field, and a source L2 address field indicating the L2 MAC address of the sender of the message. A neighbor advertisement message has a type field with a value of 136, a target address field, and a target L2 address field indicating the L2 MAC address of the receiver to which the message is being sent.

[0042] The following sections describe certain exemplary embodiments of multilink address resolution in AP multilink devices (MLDs), non-AP MLDs, and / or non-MLD STAs in the context of legacy (HE / VHT / HT) STAs.

[0043] Figure 4 shows an example configuration of a communication device according to the present disclosure. The communication device may be implemented as an AP and STA and configured for multilink address resolution according to the present disclosure. As shown in Figure 4, the communication device 400 may include a circuit 414, at least one radio transmitter 402, at least one radio receiver 404, and at least one antenna 412 (for brevity, only one antenna is shown in Figure 4 for illustrative purposes). The circuit 414 may include at least one controller 406 for use in performing, with software and hardware assistance, tasks designed to be performed by at least one controller 406, including controlling communication with one or more other communication devices in a multiple input and multiple output (MIMO) wireless network. The circuit 414 may also include at least one transmit signal generator 408 and at least one receive signal processor 410. At least one controller 406 may control at least one transmit signal generator 408 for generating MAC frames (e.g., data frames, administration frames, and action frames) to be sent through at least one radio transmitter 402, and at least one receive signal processor 410 for processing MAC frames (e.g., data frames, administration frames, and action frames) received through at least one radio receiver 404 from one or more other communication devices. The at least one transmit signal generator 408 and the at least one receive signal processor 410 may be standalone modules of a communication device 400 that communicates with at least one controller 406 for the functions described above, as shown in Figure 4. Alternatively, the at least one transmit signal generator 408 and the one receive signal processor 410 may be included in at least one controller. As will be seen to those skilled in the art, the arrangement of these functional modules is flexible and may vary depending on actual needs and / or requirements. Data processing, storage, and other related control devices may be provided on a suitable circuit board and / or within a chipset.In various embodiments, during 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.

[0044] The communication device 400 provides functions required for multilink address resolution during operation. For example, the communication device 400 may be an STA coordinating with a first MLD, and at least one radio receiver 404 of the communication device 400 may, during operation, receive an address resolution request from a requesting communication device (e.g., a non-MLD STA or a non-AP MLD STA) including the Internet Protocol (IP) address of the first MLD. The circuit 414 (e.g., at least one receive signal processor 410 of the circuit 414) may, during operation, process a first data frame to determine whether the requesting communication is coordinating with a second MLD. A circuit (for example, at least one transmit signal generator 408 of circuit 414) may, during operation, generate a second data frame containing an address resolution response, the address resolution response containing either (i) the medium access control (MAC) address of communication device 400 in response to a determination that the requesting communication device is not coordinating with the second MLD, or (ii) the MAC address of the first MLD in response to a determination that the requesting communication device is coordinating with the second MLD. A wireless transmitter 402 may, during operation, transmit the second data frame, for example, to the requesting communication device.

[0045] For example, communication device 400 may be an AP that is working with an AP MLD equipped with proxy ARP functionality to respond to ARP requests on behalf of an associated STA (e.g., a non-MLD STA, or an STA of a first non-AP MLD associated with an AP MLD). At least one radio receiver 404 of communication device 400 may, during operation, receive a first data frame from a requesting communication device (e.g., a non-MLD STA or an STA of a second non-AP MLD), the address resolution request containing the IP address of a first MLD associated with an AP MLD. Circuit 414 (e.g., at least one receive signal processor 410 of circuit 414) may, during operation, process the first data frame to determine whether the requesting communication device is working with a second MLD. A circuit (for example, at least one transmit signal generator 408 of circuit 414) may, during operation, generate a second data frame containing an address resolution response, the address resolution response containing either (i) the MAC address of the associated STA in response to a determination that the requesting communication device is not coordinating with the second MLD, or (ii) the MAC address of the first MLD with which the associated STA is coordinating in response to a determination that the requesting communication device is coordinating with the second MLD. A radio transmitter 402 may, during operation, transmit the second data frame, for example, to the requesting communication device.

[0046] Figure 5 shows a flowchart 500 illustrating the communication method according to the present disclosure. In step 502, the requesting communication device receives a first data frame containing an address resolution request, the address resolution request containing the IP address of the first MLD. In step 504, the requesting communication device determines whether or not it is cooperating with a second MLD. In step 506, the requesting communication device generates a second data frame containing an address resolution response. The address resolution response may contain either (i) the MAC address of one of several communication devices cooperating with the first MLD in response to the determination that the requesting communication device is not cooperating with the second MLD, or (ii) the MAC address of the first MLD in response to the determination that the requesting communication device is cooperating with the second MLD.

[0047] The following sections describe a first embodiment of this disclosure relating to multilink address resolution in AP MLD, non-AP MLD, and / or non-MLD STA, where AP MLD and non-AP MLD use the same MAC SAP for both MLD and non-MLD connections.

[0048] In a first embodiment of this disclosure, the MLD uses the same MAC SAP for both MLD and non-MLD connections. Figures 6A and 6B show schematic diagrams 600 and 620 illustrating an example configuration of AP MLD602 and non-AP MLD622 for multilink address resolution and their respective Internet Layers 604 and 624 at their respective network interface layers, according to a first embodiment of this disclosure. AP MLD602 and non-AP MLD622 each hold a single IP address 606 and 626, which maps to MLD MAC addresses 608 and 628, respectively. For example, AP MLD602 and non-AP MLD622 route all ARP and ND messages received from links 610 and 630 through either the legacy ARP message path or the MLD ARP message path through MAC SAPs 612 and 632 of MLD602 and 622, respectively. As a result, MLD602 and 622 always return their respective MLD MAC addresses 608 and 628 as their hardware / L2 MAC addresses.

[0049] Figure 7 shows a flowchart 700 illustrating communication between an AP MLD702 and a non-AP MLD712 for multilink address resolution according to a first embodiment of the present disclosure. AP MLD702 is associated with two APs (AP1, AP2 704) operating on the 5GHz and 6GHz frequency bands, respectively. AP MLD702 is associated with a non-AP MLD1 712 which is associated with two STAs (STA1, STA2 714) operating on the 5GHz and 6GHz frequency bands, respectively.

[0050] This example shows a non-AP MLD (e.g., non-AP MLD1 712) resolving the IP address of an associated AP MLD (e.g., AP MLD702). The STA2 714 of non-AP MLD1 712 may initiate an ARP query by sending a first data frame 722 to AP MLD702 over the 6GHz link (frequency band), which contains a broadcast address in its DA field 726 and an Address Resolution Request (ARP Request) 724. The broadcast address in the DA field 726 means that the first data frame 722 will be broadcast to all STAs and non-AP MLDs associated with AP MLD702. The ARP Request 724 contains the IP address of AP MLD702 in the Target IP field 728, indicating that non-AP MLD1 712 is attempting to resolve the IP address to obtain the corresponding MAC address of AP MLD702.

[0051] Next, AP2 704 of AP MLD702 receives a first data frame 722 on the 6GHz link with its DA field set to the broadcast address. AP2 704 forwards the first data frame 722', which contains an ARP request 724', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), including non-AP MLD1 712. AP2 704 sets its SA field 727' to the MAC address of non-AP MLD1 712 to indicate that the original source of the first data frame 722' is non-AP MLD1 712. The target IP address contained in the target IP field 728' of the ARP request 724' received by STA2 714 does not match the IP address of that MLD, so STA2 714 either ignores the ARP request 724' or rejects it as a loopback frame.

[0052] On the other hand, since the target IP address included in the target IP field 728 of the ARP request 724 received by AP2 704 matches the IP address of its MLD, AP2 704 may generate a second data frame 732 containing an address resolution response (ARP response) 734 and send it to non-AP MLD1 712 over the 6GHz link. AP MLD 702 provides its MAC address in the source hardware field 736 of the ARP response 734. The ARP response 734 also includes the MAC address and IP address of non-AP MLD1 in the target hardware field 738 and target IP field 739, respectively, indicating non-AP MLD1 712 as the target recipient of the ARP response 734.

[0053] Since the target IP address contained in the target IP field 739 of the ARP response 734 received by STA2 714 matches the IP address of its MLD, STA2 714 may process the second data frame 732 and update its ARP cache to map the IP address of the AP MLD (AP-MLD-IP) in the source IP field 737 of the ARP response 734 to the MAC address of the AP MLD (AP-MLD-M) in the source hardware field 736. As a result, the ARP query is resolved.

[0054] Next, the non-AP MLD712 may send the subsequent data frame (IP packet) 742 to AP MLD702. The IP packet destined for AP-MLD-IP will be addressed to AP-MLD-M at the IP layer, but since the non-AP MLD712 is associated with AP-MLD, it knows all of AP MLD's MAC addresses, and therefore will set the RA field 744 of the data frame containing IP packet 742 to the MAC address of one of AP MLD702's APs (in this case, AP2 704). As can be seen, address resolution works well in this case.

[0055] Figure 8 shows a flowchart illustrating communication 800 between two non-AP MLDs 812 and 822 via AP MLD 802 for multilink address resolution, according to a first embodiment of the present disclosure. AP MLD 802 is associated with two APs (AP1 and AP2 804) operating on the 5GHz and 6GHz frequency bands, respectively. AP MLD 802 is associated with non-AP MLD1 812 and non-AP MLD2 822. Non-AP MLD1 812 is associated with two STAs (STA1 and STA2 814) operating on the 5GHz and 6GHz frequency bands, respectively, and non-AP MLD2 822 is associated with two STAs (STA3 and STA4 824) operating on the 5GHz and 6GHz frequency bands, respectively.

[0056] This example shows a non-AP MLD (e.g., non-AP MLD1 812) resolving the IP address of another non-AP MLD (e.g., non-AP MLD2 822). The STA2 814 of non-AP MLD1 812 may initiate an ARP query by generating a first data frame 832 containing a broadcast address in its DA field 835 and an Address Resolution Request (ARP request) 834, and sending it to AP MLD 802 on the 6GHz link (frequency band). The broadcast address in the DA field 835 indicates that the first data frame 832 is being broadcast to all relevant STAs and non-AP MLDs. The ARP request 834 contains the IP address of non-AP MLD2 822 in its target IP field 839, indicating that non-AP MLD1 812 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 822.

[0057] Next, AP2 804 of AP MLD802, receiving the first data frame 832 on the 6GHz link, forwards the first data frame 832', which contains the ARP request 834', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), including non-AP MLD1 812 and non-AP MLD2 822. The SA field 835' contains the MAC address of non-AP MLD1 812, indicating that the original source of the first data frame 832' is non-AP MLD1 812. The target IP addresses contained in the target IP field 839' of the ARP request 834' received by STA2 814 and AP2 804 do not match the IP addresses of their respective MLDs, so STA2 814 and AP2 804 either ignore the ARP request 834' or reject it as a loopback frame.

[0058] On the other hand, the target IP address included in the target IP field 839' of the ARP request 834' received by STA4 824 matches the IP address of its non-AP MLD2 (STA-MLD2-IP), so STA4 824 may generate a second data frame 842 containing an address resolution response (ARP response) 844 and send it to AP MLD 802 over the 6GHz link. Non-AP MLD2 822 provides its MAC address (STA-MLD2-M) in the source hardware field 846 of the ARP response 844. The ARP response 844 also includes the MAC address and IP address (STA-MLD1-M and STA-MLD1-IP) of non-AP MLD1 812 in the target hardware field 848 and target IP field 849, respectively, indicating non-AP MLD1 812 as the target recipient of the ARP response 844.

[0059] Upon receiving the second data frame 842, AP MLD 802 confirms that the ARP response 844 contained within the second data frame 842 is directed to the associated non-AP MLD (in this case, non-AP MLD1 based on the MAC address (STA-MLD1-M) in the DA field), and forwards the second data frame 842' containing the ARP response 844' to non-AP MLD1 812 (in this case, from AP2 804 to STA2 814 via the 6GHz link) through one of the cooperating APs.

[0060] Since the target IP address contained in the target IP field 849' of the ARP response 844' received by STA2 814 matches the IP address of its MLD (STA-MLD1-IP), non-AP MLD1 812 may then process the second data frame 842' to update its ARP cache in order to map the IP address of non-AP MLD2 (STA-MLD2-IP) in the source IP field 847' of the ARP response 844' to the MAC address of non-AP MLD2 (STA-MLD2-M) in the source hardware field 846'. As a result, the ARP query is resolved.

[0061] Next, non-AP MLD1 812 may send the subsequent data frame (IP packet) 852 to non-AP MLD2 822 via AP MLD802. The IP packet destined for STA-MLD2-IP will be addressed to STA-MLD2-M at the IP layer, with the DA field 855 of the subsequent data frame 852 set to the MLD MAC address of non-AP-MLD2 822 (STA-MLD2-M) at the MLD level, based on the record in its ARP cache.

[0062] Upon receiving IP packet 852, AP MLD 802 confirms that IP packet 852 is destined for the associated non-AP MLD (in this case, non-AP MLD2 (STA-MLD2-M) based on DA field 855) and forwards IP packet 852' to non-AP MLD2 822 (in this case, from AP2 804 to STA4 824 via the 6GHz link) through one of the cooperating APs. Noting that non-AP MLD2 822 is associated with AP MLD 802 and therefore AP MLD 802 knows the L2 MAC address of STA4 824, AP MLD 802 can translate the MLD address of the non-AP MLD (STA-MLD2-M) to the MAC address of STA4 (STA4-M) in RA field 853' when forwarding IP packet 852' to STA4 824. In this way, IP packet 852' will be accurately received by STA4 824 and there will be no issues with the frame transmitted via AP-MLD802.

[0063] However, for ARP performed under this first embodiment of the present disclosure, a frame sent by a non-AP MLD (e.g., non-AP MLD1) directly over the link (without going through AP MLD802) to another non-AP MLD (e.g., non-AP MLD2) would fail because the RA field would be set to the MLD MAC address instead of the STA's L2 MAC address. Returning to the example shown in Figure 8, after the ARP query is resolved, non-AP MLD1 812 may want to send a public action frame (Access Network Query Protocol (ANQP) request frame) 862 directly over the link to non-AP ML2 822. Noting that non-AP MLD1 812 is not associated with non-AP MLD2 822, and therefore the L2 MAC address of STA4 824 may not be known to non-AP MLD1 812, the RA field 863 of the ANQP request frame 862 is set to the MLD MAC address of non-AP MLD2, rather than the L2 MAC address of STA4. This would cause the ANQP request 862 sent over the direct link to be dropped or ignored by STA4 824.

[0064] Figure 9 shows a flowchart 900 illustrating communication between a non-AP MLD 922 and a legacy STA 912 via an AP MLD 902 for multilink address resolution, according to a first embodiment of the present disclosure. The AP MLD 902 is associated with two APs (AP1, AP2 904) operating on the 5GHz and 6GHz frequency bands, respectively. The AP MLD 902 is associated with STA5 912 and the non-AP MLD2 922. The non-AP MLD2 922 is associated with two STAs (STA3, STA4 924) operating on the 5GHz and 6GHz frequency bands, respectively. STA5 912 operates on the 6GHz frequency band.

[0065] This example shows a legacy STA (e.g., STA5 912) resolving the IP address of a non-AP MLD (e.g., non-AP MLD2 922). STA5 912 may initiate an ARP query by generating a first data frame 932 containing a broadcast address in its DA field 935 and an Address Resolution Request (ARP request) 934, and sending it to AP MLD 902 over a 6GHz link (frequency band). The broadcast address in the DA field 935 indicates that the first data frame 932 is being broadcast to all relevant STAs and non-AP MLDs. The ARP request 934 contains the IP address of non-AP MLD2 924 in the target IP field 939, indicating that STA5 912 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 924.

[0066] Next, AP2 904 of AP MLD902, receiving the first data frame 932 on the 6GHz link, forwards the first data frame 932', which contains the ARP request 934', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), including STA5 912 and non-AP MLD2 924. The SA field 935' contains the MAC address of STA5 912, indicating that the original source of the first data frame 932' is STA5 912. The target IP addresses contained in the target IP field 939' of the ARP request 934' received by STA5 912 and AP2 904 do not match their respective L2 and MLD MAC IP addresses, so STA5 912 and AP2 904 either ignore the ARP request 934' or reject it as a loopback frame.

[0067] On the other hand, the target IP address included in the target IP field 939' of the ARP request 934' received by STA4 924 matches the IP address of its non-AP MLD (STA-MLD2-IP), so STA4 924 may generate a second data frame 942 containing an address resolution response (ARP response) 944 and send it to AP MLD 902 over the 6GHz link. Non-AP MLD2 924 provides its MAC address (STA-MLD2-M) in the source hardware field 946 of the ARP response 944. The ARP response 944 also includes the MAC address and IP address (STA5-M and STA5-IP) of STA5 912 in the target hardware field 948 and target IP field 949, respectively, indicating STA5 912 as the target recipient of the ARP response 944.

[0068] Upon receiving the second data frame 942, AP MLD902 confirms that the ARP response 944 contained within 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', including the ARP response 944', to STA5 912 via the cooperating AP (in this case, AP2 904 via the 6GHz link) in the 6GHz band.

[0069] Since the target IP address contained in the target IP field 949' of the ARP response 944' received by STA5 912 matches that IP address (STA5-IP), STA5 912 may then process the second data frame 942' to update its ARP cache in order to map the IP address of the non-AP MLD (STA-MLD2-IP) in the source IP field 947' of the ARP response 944' to the MAC address of the non-AP MLD (STA-MLD2-M) in the source hardware field 946'. As a result, the ARP query is resolved.

[0070] Next, STA5 912 may send the subsequent data frame (IP packet) 952 to non-AP MLD2 922 via AP MLD 902. The IP packet destined for STA-MLD2-IP will have its DA field 955 set to the MLD MAC address of non-AP MLD2 922 (STA-MLD2-M), and will be addressed to STA-MLD2-M at the IP layer.

[0071] Upon receiving IP packet 952, AP MLD902 verifies that IP packet 952 is destined for the associated non-AP MLD (in this case, non-AP MLD2 922 based on the IP address in the target IP field 957 (STA-MLD2 IP)) and forwards IP packet 952' to the target hardware, i.e., non-AP MLD2 922 (in this case, from AP2 904 to STA4 924 via the 6GHz link) through one of the cooperating APs. Noting that non-AP MLD2 922 is associated with AP MLD902, and therefore AP MLD902 knows the L2 MAC address of STA4 924, AP MLD902 can translate the MLD address of non-AP MLD2 (STA-MLD2-M) to the MAC address of STA4 (STA4-M) in the RA field 953' when forwarding IP packet 952' to STA4 924. In this way, IP packet 952' will be accurately received by STA4 924, and there will be no problems with the frame transmitted via AP-MLD902.

[0072] However, for ARP performed under this first embodiment of the present disclosure, frames sent by a legacy STA (e.g., STA5 912) directly over the link (e.g., without going through AP MLD 902) to a non-AP MLD (e.g., non-AP MLD2 922) would fail because the RA field is set to the MLD MAC address of the non-AP MLD2, rather than the L2 MAC address of the STA. Returning to the example shown in Figure 9, after the ARP query has been resolved, STA5 912 may want to send a public action frame (ANQP request frame) 962 directly over the link to the non-AP MLD2 922. Noting that STA5 912 is not associated with the non-AP MLD2 922 and therefore the L2 MAC address of STA4 924 may not be known to STA5 912, 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), rather than the L2 MAC address of STA4. This would cause ANQP request frame 962 sent over a direct link to be dropped or ignored by STA4 924.

[0073] Figure 10 shows a flowchart 1000 illustrating communication between AP MLD 1002, one non-AP MLD2 1012, and a legacy STA5 1022 for multilink address resolution according to a first embodiment of the present disclosure. AP MLD1002 is associated with two APs (AP1, AP2 1004) operating on the 5GHz and 6GHz frequency bands, respectively. AP MLD1002 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 5GHz and 6GHz frequency bands, respectively. STA5 1022 operates on the 6GHz frequency band.

[0074] This example shows a non-AP MLD (e.g., non-AP MLD2 1012) resolving the IP address of a legacy STA (e.g., STA5 1022). STA4 of non-AP MLD2 1012 may initiate an ARP query by generating a first data frame 1032 containing a broadcast address in its DA field 1035 and an Address Resolution Request (ARP request) 1034, and sending it to AP MLD1002 on the 6GHz link (frequency band). The broadcast address in the DA field 1035 indicates that the first data frame 1032 is being broadcast to all relevant STAs and non-AP MLDs. The ARP request 1034 contains the IP address of STA5 1022 in its target IP field 1039, indicating that non-AP MLD2 1012 is attempting to resolve the IP address to obtain the corresponding MAC address of STA5 1022.

[0075] Next, AP2 1004 of AP MLD1002, receiving the first data frame 1032 on the 6GHz link, forwards the first data frame 1032', which contains the ARP request 1034', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), including non-AP MLD2 1012 and STA5 1022. The SA field 1035' contains the MAC address of non-AP MLD2 1012, indicating that the original source of the first data frame 1032' is non-AP MLD2 1012. The target IP addresses contained in the target IP field 1039' of the ARP request 1034' received by STA4 1014 and AP2 1004 do not match their respective L2 and MLD MAC IP addresses, so STA4 1014 and AP2 1004 either ignore the ARP request 1034' or reject it as a loopback frame.

[0076] On the other hand, since the target IP address included in the target IP field 1039' of the ARP request 1034' received by STA5 1022 matches its IP address (STA5-IP), STA5 1022 may generate a second data frame 1042 containing an address resolution response (ARP response) 1044 and send it to AP MLD 1002 over the 6GHz link. STA5 1022 provides its L2 MAC address (STA5-M) in the source hardware field 1046 of the ARP response 1044. The ARP response 1044 also includes the MAC address and IP address of the non-AP MLD2 1012 (STA-MLD2-M and STA-MLD2-IP) in the target hardware field 1048 and target IP field 1049, respectively, indicating the non-AP MLD2 1012 as the target recipient of the ARP response 1044.

[0077] Upon receiving the second data frame 1042, AP MLD 1002 confirms that the ARP response 1044 contained within the second data frame 1042 is directed to the associated STA (in this case, non-AP MLD2 1012 based on the MAC address in the DA field (STA-MLD2-M)), and forwards the second data frame 1042' containing the ARP response 1044' to the non-AP MLD2 1012 (in this case, from AP2 1004 to STA4 1014 via the 6GHz link) through one of the cooperating APs.

[0078] Since the target IP address contained in the target IP field 1049' of the ARP response 1044' received by STA4 1014 matches that IP address (STA-MLD2-IP), STA4 1014 may then process the second data frame 1042' to update its ARP cache in order to map the IP address of STA5 (STA5-IP) in the source IP field 1047' of ARP response 1044' to the MAC address of STA5 (STA5-M) in the source hardware field 1046' of ARP response 1044'. As a result, the ARP query is resolved. STA4 1014 may then process the second data frame 1042' to update its ARP cache in order to map the IP address of STA5 (STA5-IP) in the source IP field 1047' of ARP response 1044' to the MAC address of STA5 (STA5-M) in the source hardware field 1046'. As a result, the ARP query is resolved.

[0079] Next, the non-AP MLD2 1012 may initiate Tunnel Direct Link Setup (TDLS) discovery by sending a subsequent data frame 1052 containing a TDLS discovery request 1054 to STA5 1022 via AP MLD 1002 operating on the 6GHz link. The TDLS discovery request comprises 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 set up a direct link with STA5 1022 (responder).

[0080] Upon receiving the subsequent data frame 1052, AP MLD 1022 verifies that the TDLS discovery request 1054 contained within data frame 1052 is directed to the associated STA (in this case, STA5 1022 based on the MAC address (STA5-M) in the DA field), and forwards data frame 1052' to STA5 1022. Noting that STA5 1022 is associated with AP MLD 1022, and therefore STA5 1022's L2 MAC address is known to AP MLD 1002, AP MLD 1002 sets STA5's MAC address (STA5-M) in the RA field 1053' when forwarding data frame 1052 to STA5 1022. In this way, the data frame will be accurately received by STA5 1022.

[0081] Upon receiving TDLS discovery request 1054', STA5 1022 may send back a TDLS discovery response action frame 1062 to STA4 1014 over the direct link, i.e., the STA's operating link (link 2 or 6GHz frequency band). However, as in the example shown in Figure 9, since STA5 1022 is not associated with non-AP MLD2 1012, and therefore STA4 1014's L2 MAC address may not be known to STA5 1022, the RA field 1063 of the TDLS discovery response action frame 1062 is set to the non-AP MLD2's MLD MAC address (STA-MLD2-M) based on the TDLS initiator field in TDLS discovery request 1054', rather than STA4's L2 MAC address. This would cause the TDLS discovery response action 1062 sent over the direct link to be dropped or ignored by STA4 1014.

[0082] Therefore, according to this disclosure, in order to accurately receive frames transmitted directly over the link by another non-AP MLD or legacy STA, in addition to the usual frame filtering criteria, a non-AP MLD should be configured to also accept certain frames in which the RA field is set to its MLD MAC address. In particular, to avoid unnecessary checking, only the RA field of certain frames is checked for the MLD MAC address, such as (i) data frames in which the frame control fields "To DS" and "From DS" are set to a value of 0 (settings used for peer-to-peer transmission), and (ii) public action frames used for peer-to-peer discovery, such as TLDS discovery response frames and group address request / response frames (used for ANQP request / response).

[0083] However, this violates the 802.11be agreement that the value of the Address 1 (RA) field in the MAC header of individually addressed frames transmitted wirelessly should be the MAC address of the receiving STA that is working with the MLD corresponding to that link (not the MLD MAC address of the MLD).

[0084] Therefore, there is a need for communication equipment and methods that provide a feasible technical solution to address one or more of the above challenges, where multilink address resolution can result in frames transmitted over a direct link being accurately received by another non-AP MLD or legacy STA, in accordance with the 802.11be agreement on setting the RA / TA fields.

[0085] According to a second embodiment of this disclosure, the IP address of an MLD is dynamically mapped to either an MLD MAC address or an L2 MAC address of an MLD. In response to an address resolution request (ARP request or neighbor request message), a determination may be made to determine which MAC address should be returned as the hardware MAC address of the MLD. This depends on whether the requesting STA, which sends an address resolution request to resolve the IP address of another MLD or STA, is an MLD or a non-MLD.

[0086] If the requesting STA is determined to be an MLD, the MLD MAC address is returned as the MLD's hardware MAC address. Conversely, if the requesting STA is determined to be a non-MLD (either an EHT or a legacy STA), the MAC address of the cooperating AP / STA operating on the link from which the address resolution request was received is returned as the MLD's hardware MAC address. Thus, from the perspective of a non-MLD, an MLD is identified by the MAC address of the cooperating AP / STA operating on the same link on which the non-MLD operates. However, if a non-MLD happens to be operating on a link that is not among any of the MLD's setup links, the MLD may be identified by its own MLD MAC address.

[0087] One possible solution to achieve the above is by MLD using different SAPs for MLD and non-MLD / legacy connections. In the following sections, a second embodiment of this disclosure is described with respect to multilink address resolution in AP MLD, non-AP MLD and / or non-MLD STA using different MAC SAPs for MLD and non-AP MLD / legacy connections.

[0088] Frames transmitted by an MLD may include an "ML indication" to indicate that they are transmitted by (or originate from) an MLD. The "ML indication" may be included in all frames transmitted by an MLD, or in frames transmitted / relayed by an AP MLD.

[0089] According to a second embodiment of this disclosure, an MLD address query mechanism is proposed for resolving MLD MAC addresses to L2 MAC addresses, which is shown in the following section with respect to Figure 18.

[0090] Furthermore, the AP MLD may provide a proxy ARP function that dynamically maps the IP address of the associated non-AP MLD to either the non-AP MLD's MLD MAC address or the non-AP MLD's L2 MAC address. To determine which MAC address should be returned as the non-MLD's hardware MAC address in response to an address resolution request (ARP request or neighbor solicitation message), the determination may be performed by the AP MLD on behalf of the non-AP MLD. This depends on whether the requesting STA, which sends the address resolution request to resolve the IP address of the non-AP MLD or STA, is an MLD or a non-MLD.

[0091] 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. Conversely, if the requesting STA is determined to be a non-MLD (either an EHT or a legacy STA), the MAC address of the cooperating STA of the MLD operating on the link from which the address resolution request was received is returned as the MLD's hardware MAC address. However, if the non-MLD is operating on a link that is not among the setup links of any of the associated non-AP MLDs, the AP MLD may return the non-AP MLD's MLD MAC address as its hardware MAC address.

[0092] According to the second embodiment, when forwarding a unicast data frame transmitted by an associated non-AP MLD to an associated non-MLD STA (e.g., a legacy STA), the AP MLD sets the SA field of the data frame being forwarded as the MAC address of the non-AP MLD's STA corresponding to the link on which the frame was received by the AP MLD. Similarly, when forwarding a unicast data frame transmitted by an associated non-MLD STA (e.g., a legacy STA) to an associated non-AP MLD, the AP MLD forwards the frame over the same link on which the frame was received, as long as the non-AP MLD has a cooperating AP operating on that link (i.e., link crossover is not permitted).

[0093] In TDLS frames sent by a non-AP MLD to a non-MLD STA (e.g., a legacy STA), relevant address fields such as the TDLS initiator STA and TDLS responder STA are set as the STA MAC address of the non-AP MLD corresponding to the transmission link (rather than the MLD MAC address).

[0094] Figures 11A and 11B show schematic diagrams 1100 and 1150 illustrating an example configuration of AP MLD1102 and non-AP MLD1152 for multilink address resolution, and their respective network interface layers for communication with their respective Internet Layers 1104 and 1154, according to a second implementation of the present disclosure. AP MLD1102 and non-AP MLD1152 each hold a single IP address 1106, 1156 mapped to MLD MAC addresses 1108, 1158, as well as MAC SAPs for the MLD (e.g., MAC-SAP1 1112, 1162) and AP / STA MAC SAPs for each linked AP / STA within the MLD (e.g., MAC-SAP2 1114, 1154 for AP1 / STA1 and MAC-SAP3 1116, 1156 for AP2 / STA2).

[0095] AP MLD1102 and non-AP MLD1152 use different MAC SAPs for MLD and non-MLD (including legacy STA) connections. The IP address of the MLD is dynamically mapped to either MLD MAC addresses 1108, 1158 or STA MAC addresses 1118, 1120, 1168, 1170. Traffic to / from MLD / DS (including ARP and ND messages) is routed through MLD MAC SAPs 1112, 1162, as indicated by lines 1122, 1172, while traffic to / from non-MLD / DS (including ARP and ND messages) is routed through STA MAC SAPs, as indicated by lines 1124, 1174. ARP / ND 1105, 1155 returns the MAC address of the corresponding MAC SAP through which the ARP / ND request was received. In other words, if an ARP / ND request is received from a non-MLD, the traffic is routed through the STA MAC SAP and the STA MAC address is returned; conversely, if an ARP / ND request is received from an MLD, the traffic is routed through the MLD MAC SAPs 1114, 1116, 1154, and 1156, and therefore the MLD MAC address is returned.

[0096] Furthermore, it is also possible that multiple IP addresses are assigned to the device, with a one-to-one mapping between the IP addresses and the MAC addresses corresponding to each MAC SAP, for example, one IP address corresponding to the MLD MAC address and one IP address corresponding to each AP / STA MAC address.

[0097] Figure 12 shows an example format of data frame 1200 according to a second embodiment of the present disclosure. 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 as 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 fragment subfield, a retry subfield, a power management subfield, a more data subfield, a protected frame subfield, and a +HT subfield.

[0098] 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 serves as an "ML indication" to identify that the transmitting / outgoing device is an MLD. The receiving STA / AP, or the STA / AP of the receiving MLD, uses the presence of the "ML indication" to determine whether the transmitting / outgoing device is an MLD, and therefore to which the received data frame is forwarded to the MAC SAP. In particular, data frames received by a receiving MLD containing such an "ML indication" are forwarded to the MLD MAC SAP, 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 the ARP / ND request was received as the receiving MLD's hardware address. Advantageously, the MLD's hardware MAC address will be precisely mapped based on the ML indication that identifies the type of requesting STA (MLD or non-MLD).

[0099] AP knows the device type of all associated devices, for example, based on capability exchange during association procedures. Even without "ML indication," AP can determine MAC SAP based on TA fields. Data frames from legacy STAs go to AP MAC SAP, while data frames from non-AP MLDs go to MLD MAC SAP.

[0100] Figure 13 shows a flowchart illustrating communication between AP MLD1302 and a non-MLD STA1312 for multilink address resolution according to a second embodiment of the present disclosure. AP MLD1302 is associated with two APs (AP1 and AP2 1304) operating on the 5GHz and 6GHz frequency bands, respectively. AP MLD1302 is associated with STA5 1312 on the 6GHz frequency band.

[0101] This example shows a legacy STA (e.g., STA5 1312) resolving the IPv4 address of an associated AP MLD (e.g., AP MLD1302). STA5 1312 may initiate an ARP query by generating a first data frame 1322 containing a broadcast address in its DA field 1325 and an Address Resolution Request (ARP request) 1324, and sending it to AP MLD1302 over a 6GHz link (frequency 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 contains the IP address of AP MLD1302 (AP-MLD-IP) in the target IP field 1329, indicating that STA5 1312 is attempting to resolve the IP address to obtain the corresponding MAC address of AP-MLD1302.

[0102] Next, AP2 1304 of AP MLD 1302, receiving the first data frame 1322 on the 6GHz link, may forward the first data frame 1322', which contains the ARP request 1324', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), which includes STA5 1312. The SA field 1325' contains the MAC address of STA5, indicating that STA5 was the original source of the first data frame 1322'. The target IP address contained in the target IP field 1329' of the ARP request 1324' received by STA5 1312 does not match its IP address, so STA5 1312 either ignores the ARP request 1324' or rejects it as a loopback frame.

[0103] On the other hand, the target IP address included in the target IP field 1329 of the ARP request 1324 received by AP2 1304 matches the IP address of its MLD, so AP2 1304 may determine the device type of the requesting device 5 1312 by confirming that the originating device is STA5 1312 based on the SA field 1325'. In this case, AP2 1304 may determine that STA5 is not an MLD, and based on this, the ARP request 1324 is forwarded to AP2 MAC SAP (not MLD MAC SAP).

[0104] The second data frame 1332, containing the Address Resolution Response (ARP response) 1334, is generated by AP MLD 1302 and transmitted via AP2's MAC SAP to STA5 1312 from AP2 1304 over the 6GHz link. The ARP response 1334 includes 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 target hardware field 1338, and STA5's IP address in the target IP field 1339, indicating that STA5 1312 is the target recipient of the ARP response 1334.

[0105] Since the target IP address contained in the target IP field 1339 of the ARP response 1334 received by STA5 1312 matches that IP address, STA5 1312 may 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 of the ARP response 1334 to the MAC address of AP2 (AP2-M) in the source hardware field 1336. As a result, the ARP query is resolved.

[0106] Next, STA5 1312 may send the subsequent data frame 1342 to AP2 1304 via AP2 MAC-SAP. Data frame 1342 addressed to AP MLD will be addressed to AP2 at the IP layer, with the RA field 1353 of data frame 1342 set to AP2's MAC address (AP2-M).

[0107] Figure 14 shows a flowchart 1400 illustrating communication between a non-AP MLD1422 and a non-MLD STA1412 via AP MLD1402 for multilink address resolution, according to a first example of a second embodiment of the present disclosure.

[0108] This example shows a legacy STA (e.g., STA5 1412) resolving the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 1422) using a common link (e.g., link 2 or 6GHz frequency band). STA5 1412 may initiate an ARP query by generating a first data frame 1432 containing a broadcast address in its DA field 1435 and an address resolution request (ARP request) 1434, and sending it to AP MLD 1402 on the 6GHz link (frequency band). The broadcast address in the DA field 1435 indicates that the first data frame 1432 is being broadcast to all relevant APs and AP MLDs. The ARP request 1434 contains the IP address of non-AP MLD2 1422 in its target IP field 1439, indicating that STA5 1412 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 1422.

[0109] Next, AP2 1404 of AP MLD1402, receiving the first data frame 1432 on the 6GHz link, may forward the first data frame 1432', which contains the ARP request 1434', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), which includes STA5 1412 and non-AP MLD2 1422. The SA field 1435' contains the MAC address of STA5 1412, indicating that the original source of the first data frame 1434' is STA5 1412. The target IP addresses contained in the target IP field 1439' of the ARP request 1434' received by STA5 1412 and AP2 1404 do not match their respective L2 and MLD MAC IP addresses, so STA5 1412 and AP2 1404 either ignore the ARP request 1434' or reject it as a loopback frame.

[0110] Based on the SA field 1435', STA4 1424 confirms that the ARP request 1434' originates from STA5 1412, and may determine that the requesting device STA5 1412 is non-MLD due to the absence of the "ML indication" in the first data frame 1432'. Based on this, the ARP request 1434' is forwarded to the ARP / IP layer via the STA4 MAC SAP. Non-AP MLD2 1422 may also record link 2 (6GHz frequency band) as the operating link for STA5.

[0111] Since the target IP address included in the target IP field 1439' of ARP request 1434' matches the IP address of non-AP MLD2 (STA-MLD2-IP), non-AP MLD2 may use its STA MAC SAP to generate a second data frame 1442 containing an address resolution response (ARP response) 1444, and send data frame 1442 to AP2 1404 via STA4. The ARP response 1444 included in data frame 1442 contains the MAC address of STA4 (STA4-M) in the source hardware field 1446, the MAC address of STA5 in the target hardware field 1448, and the IP address of STA5 in the target IP field 1449, indicating that STA5 1412 is the target recipient of ARP response 1444.

[0112] Upon receiving the second data frame 1442, AP MLD 1402 verifies, based on the MAC address (STA5-M) in the target hardware field 1448, that the ARP response 1444 contained within the second data frame 1442 is directed to STA5, and forwards the second data frame 1442', including the ARP response 1444', to STA5 1412 via AP2 1404, which is operating on STA5's operational link (link 2). It is noted that the SA field of the second data frame 1442' is set to the MAC address of STA4 (and not the MLD MAC address of a non-AP MLD) to verify that the original transmitting STA of the second data frame 1442 was STA4 1424.

[0113] Upon receiving the second data frame 1442, STA5 1412 may process it and update its ARP cache to map the IP address of the non-AP MLD (STA-MLD2-IP) in the source IP field 1447' of the ARP response 1444' to the MAC address of STA4 (STA4-M) in the source IP field 1446'. As a result, the ARP query is resolved.

[0114] Next, STA4 1424 of the non-AP MLD2 1422 may initiate TDLS discovery by sending a subsequent data frame 1452 containing a TDLS discovery request 1454 to STA5 1412. Since it is now known that the peer device is a non-MLD STA, i.e., STA5 1412, and is operating on link 2, STA4 1424 is used as the TDLS initiator. The TDLS discovery request 1454 comprises 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.

[0115] Upon receiving the subsequent data frame 1452, AP MLD 1402, based on STA5's MAC address (STA5-M) in the TDLS responder field 1459, verifies that the TDLS discovery request 1454 contained within data frame 1452 is directed to STA5 1412, and forwards data frame 1452', received from non-AP MLD2 1422, which contains STA4's MAC address (STA4-M) and TDLS discovery request 1454' in the SA field 1455', to STA5 1412. When forwarding data frame 1452' to STA5 1412, AP MLD 1402 sets STA5's MAC address (STA5-M) in the RA field 1453'. In this way, the data frame will be accurately received by STA5 1412.

[0116] Upon receiving TDLS discovery request 1454', STA5 1412 may send back a TDLS discovery response action frame 1462 to STA4 1424 over the direct link, i.e., STA5's operational link (link 2). Based on the mapping stored in its ARP cache, STA5 1412 can set the RA field 1463 of the TDLS discovery response action frame 1462 to the MAC address of STA4. In this way, frames such as the TDLS discovery response action frame 1462 sent by STA5 1412 to the non-AP MLD 1422 over the direct link are accurately received via STA4 1424.

[0117] This solves the problem of frames transmitted between a legacy STA and a non-AP MLD over a direct link failing to be received correctly, as shown in the first embodiment of this disclosure. Since both the TDLS initiator field and the SA field in the link identifier element of the TDLS discovery request frame relayed by the AP are set as the STA MAC address, there will be no confusion at the receiving peer STA.

[0118] When forwarding a group address data frame received from an associated non-MLD (e.g., 1432), the AP MLD shall forward the frame on the same link (e.g., 6GHz link) on which the frame was received, as long as there is an associated non-AP MLD operating on that link. If there is an associated non-AP MLD operating in power-save mode on that link and another link (e.g., 5GHz link) that is actively operating, the AP shall buffer the data frame on the 6GHz link for such non-AP MLDs and notify the non-AP MLDs of the buffered frame on the 5GHz link, for example, using a TIM element in a DTIM beacon frame. This ensures that the data frame is forwarded via the non-AP MLD's exact STA MAC SAP and that the exact STA MAC address (of the STA operating on the same link as the non-MLD) is returned as the non-AP MLD's hardware MAC address.

[0119] Figure 15 shows a flowchart 1500 illustrating communication between a non-AP MLD1522 and a non-MLD STA1512 via AP MLD1502 for multilink address resolution, according to a second example of a second embodiment of the present disclosure.

[0120] This second example shows a legacy STA (e.g., STA5 1512) resolving the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 1522) without a common link. If the non-MLD is inadvertently operating on a link that is not among some of the related non-AP MLD's setup links, the AP MLD has no choice but to forward any group address data frames received from the related non-MLD that are destined to reach all related non-AP MLDs over all other setup links. This results in multiple ARP requests and ARP responses, and as a result, the legacy STA's ARP can cache any one of the non-AP MLD's multiple STA MAC addresses. In any case, communication between the legacy STA and the non-AP MLD would succeed if it inadvertently occurred via the related AP MLD; however, in this case, there is no direct link between the legacy STA and the non-AP MLD, so direct link communication is not possible regardless of ARP caching.

[0121] Returning to the example, STA5 is operating on link 3, while non-AP MLD2 is operating on links 1 and 2. STA5 1512 may initiate an ARP query by generating a first data frame 1532 containing a broadcast address in its DA field 1535 and an address resolution request (ARP request) 1534, and sending it to AP MLD 1502 in the 2.4GHz frequency band (link 3). The broadcast address in the DA field 1535 indicates that the first data frame 1532 is being broadcast to all relevant STs and non-AP MLDs. The ARP request 1534 contains the IP address of non-AP MLD2 1522 in its target IP field 1539, indicating that STA5 1512 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 1522.

[0122] Next, AP3 1508 of AP MLD 1502, having received the first data frame 1532 on the 2.4GHz link, may forward the first data frame 1532', which includes the ARP request 1534', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), which includes STA3 1524, STA4 1526, and STA5 1512, on all three links (2.4, 5, and 6GHz links). The SA field 1535' contains the MAC address of STA5 1512, indicating that the original source of the first data frame 1532' is STA5 1512.

[0123] Since the target IP address included in the target IP field 1539' of ARP request 1534' matches the IP address of non-AP MLD2 1522 (STA-MLD2-IP), non-AP MLD2 1522 may receive two ARP requests 1534' via both STA3 1524 and STA4 1526. Both STA3 1524 and STA4 1526, based on the SA field 1535', confirm that ARP request 1534' originates from STA5 1512, and due to the absence of the "ML indication" in the first data frame 1532', they may determine that the requesting device STA5 1512 is non-MLD. Based on this, ARP request 1534' is forwarded to STA3 and STA4 MAC SAPs.

[0124] Non-AP MLD2 1522 may generate a second data frame 1542 containing an address resolution response (ARP response) 1544 via its respective STA MAC SAP and transmit the data frame 1542 to AP1 1504 and AP2 1506 via the 5GHz frequency band (Link 1) and the 6GHz frequency band (Link 2), respectively. The two ARP responses 1544 contained within the data frame 1542 generated by STA3 1524 and STA4 1526 include their respective MAC addresses (STA3-M / STA4-M) in the source hardware field 1546, the MAC address of STA5 in the target hardware field 1548, and the IP address of STA5 in the target IP field 1549, indicating that STA5 1512 is the target recipient of the ARP response 1544.

[0125] Having received both of the second data frames 1542, AP MLD 1502, based on the MAC address (STA5-M) in the target hardware field 1548, verifies that the ARP response 1544 contained within the second data frame 1542 is directed to STA5 1512, and forwards the second data frame 1552', which contains the ARP response 1544', to STA5 1512 via AP3 1508 operating on the STA5 operational link (link 3). It should be noted that the SA field 1545' of the second data frame 1542' is set to the MAC addresses of STA3 and STA4 to identify that the original transmitting STAs of the second data frame 1542 were STA3 1524 and STA4 1524, respectively.

[0126] Upon receiving ARP responses 1544' contained within two second data frames 1542, STA5 1512 may process them and update its ARP cache twice to map the IP address of the non-AP MLD (STA-MLD2-IP) in the source IP field 1547' of ARP response 1544' to both MAC addresses (STA3-M / STA4-M) in the source hardware field 1546'. However, the MAC address updated later (e.g., STA4-M) will remain in the ARP cache as the MAC address of the non-AP MLD2.

[0127] Next, STA4 1526 of the non-AP MLD2 1522 may initiate TDLS discovery by sending a subsequent data frame 1552 containing a TDLS discovery request 1554 to STA5 1512. STA4 1526 is used as the TDLS initiator. The TDLS discovery request 1554 comprises a TDLS initiator field set in the MAC address of STA4 and a TDLS responder field 1559 set in the MAC address of STA5 1512.

[0128] Upon receiving the subsequent data frame 1522, AP MLD 1502, based on STA5's MAC address (STA5-M) in the TDLS responder field 1559, verifies that the TDLS discovery request 1554 contained in data frame 1552 is directed to STA5 1512. It then forwards data frame 1552', received from non-AP MLD2 1522 and containing STA4's MAC address (STA4-M) in the SA field 1555' and the TDLS discovery request 1554', to STA5 1512 via STA5's operational link. AP MLD 1502 can translate STA5's MAC address (STA5-M) in the RA field 1553' when forwarding data frame 1552' to STA5 1512. In this way, the data frame will be accurately received by STA5 1512.

[0129] Upon receiving TDLS discovery request 1554', STA5 1512 may send a TDLS discovery response action frame 1562 over link 3. Based on the mapping stored in its ARP cache, STA5 1512 sets the RA field 1563 of the TDLS discovery response action frame 1562 to the MAC address of STA4 (STA4-M). However, since the non-AP MLD2 does not have a cooperating STA operating on link 3, the frame sent from STA5 1512 to the non-AP MLD2 1522 will fail even if the RA is set correctly.

[0130] Figure 16 shows a flowchart 1600 illustrating communication between AP MLD1602, non-AP MLD1622, and non-MLD STA1612 for multilink address resolution, according to a third example of a second embodiment of the present disclosure.

[0131] This third example is the same as the first example shown in Figure 14, but it considers a scenario where the AP MLD1402 replicates broadcast data on all links (link 1 and link 2).

[0132] Even if a non-MLD operates on one of several setup links of an associated non-AP MLD, the presence of other legacy STAs or non-AP MLDs on other links may leave the AP MLD with no choice but to forward any group address data frames received from the associated non-MLD across all setup links. This can result in multiple ARP requests and ARP responses. However, the AP MLD can help the legacy STA maintain an accurate ARP cache by forwarding only ARP responses received on the link where the legacy STA (addressed in the DA field) is operating. It is also possible that a non-AP MLD might initiate a TDLS discovery / setup request frame on the wrong link with a legacy STA without knowing which link is operational. In such cases, the AP MLD may assist the legacy STA by forwarding the TDLS discovery / setup request frame over the correct link, and may even modify the SA and TDLS initiator fields to reflect the initiator, the correct STA of the non-AP MLD (the one operating on the same link as the legacy STA, STA4 in this example). This, however, requires the AP MLD to inspect the tunnel data frame and modify the data frame payload.

[0133] This third example shows a legacy STA (e.g., STA5 1612) resolving the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 1622) using a common link (e.g., Link 2 or the 6GHz frequency band). STA5 1612 may initiate an ARP query by generating a first data frame 1632 containing a broadcast address in its DA field 1635 and an address resolution request (ARP request) 1634, and sending it to AP MLD 1602 on the 6GHz link (frequency band). The broadcast address in the DA field 1635 indicates that the first data frame 1632 is being broadcast to all relevant STAs and non-AP MLDs. The ARP request 1634 contains the IP address of non-AP MLD2 1622 in the target IP field 1639, indicating that STA5 1612 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 1622.

[0134] Next, AP2 1606 of APMLD 1602, receiving the first data frame 1632 on the 6GHz link, may forward the first data frame 1632', which includes the ARP request 1634', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), which includes STA3 1624, STA4 1626, and STA5 1612, on all links (5 and 6GHz links). The SA field 1635' contains the MAC address of STA5 1612, indicating that the original source of the first data frame 1634' was STA5 1612.

[0135] Since the target IP address included in the target IP field 1639' of ARP request 1634' matches the IP addresses of STA3 1624 and STA4 1626 (STA-MLD2-IP), a non-AP MLD2 may receive two ARP requests 1634' via both STA3 1624 and STA4 1626. Both STA3 1624 and STA4 1626, based on the SA field 1635', confirm that ARP request 1634' originates from STA5 1612, and due to the absence of the "ML indication" in the first data frame 1632', they may determine that the requesting device STA5 1612 is a non-MLD. Based on this, ARP request 1634' is forwarded to STA3 and STA4 MAC SAPs.

[0136] STA3 1624 and STA4 1626 may use their respective STA MAC SAPs to generate a second data frame 1642 containing an address resolution response (ARP response) 1644, and transmit the data frame 1642 to AP1 1604 and AP2 1606, respectively, via the 5GHz frequency band (Link 1) and the 6GHz frequency band (Link 2). The two ARP responses 1644 contained within the data frame 1642 generated by STA3 1624 and STA4 1626 include their respective MAC addresses (STA3-M / STA4-M) in the source hardware field 1646, the MAC address of STA5 in the target hardware field 1648, and the IP address of STA5 in the target IP field 1649, indicating that STA5 1612 is the target recipient of the ARP response 1644.

[0137] Having received both second data frames 1642, AP MLD1602 verifies, based on the MAC address (STA5-M) in the DA field, that the ARP response 1644 contained within the second data frame 1642 is directed to STA5 1612. Noting that STA5 1612 operates on link 2 (6GHz frequency band), AP MLD1602 forwards only the second data frame 1642' containing the ARP response 1644' received on STA5's operating link to STA5 1612 via AP2 1606 operating on that link, and does not forward the second data frame 1642' containing the ARP response 1644' received on the other link (link 1). It is noted that the SA field 1645' of the second data frame 1642' is set to the MAC address of STA4 to identify that the original transmitting STA of the second data frame 1642 is STA4 1624.

[0138] Upon receiving the ARP response 1644' contained within the second data frame 1642', STA5 1612 may process the ARP response and update its ARP cache to map the IP address of the non-AP MLD (STA-MLD2-IP) in the source IP field 1647' of ARP response 1644' to STA4-M in the source hardware field 1646'.

[0139] Next, the non-AP MLD2 1622 may initiate TDLS discovery by sending a subsequent data frame 1652 containing a TDLS discovery request 1654 to STA5 1612 through one of its cooperating STAs (in this case, STA3 1624 via link 1). The TDLS discovery request 1654 comprises 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.

[0140] Upon receiving the subsequent data frame 1652 via link 1, AP1 1604 of AP MLD1602 confirms, based on the MAC address of STA5 (STA5-M) in the TDLS responder field 1659, that the TDLS discovery request 1654 contained in data frame 1652 is directed to STA5 1612. Noting that STA5 1612 operates on link 2, AP1 1604 corrects the MAC addresses in the SA field 1655' and TDLS initiator field 1658' to relate to STA4 1626 (STA4-M) operating on the same link as STA5 1612, and can then forward data frame 1652', received from non-AP MLD2 1622 and containing the corrected SA field 1655' and TDLS initiator field 1658', to STA5 1612 via AP2 1606 operating on STA5's operating link. In this way, even though non-AP MLD2 1622 transmitted data frame 1642 over the wrong link, data frame 1642 is accurately received by STA5 1612.

[0141] Upon receiving the TDLS discovery request 1654', STA5 1612 may send back the TDLS discovery response action 1662 to the source directly over the link. Based on the TDLS initiator field 1658', STA5 1612 can set the RA field 1663 of the TDLS discovery response action frame 1662 to the MAC address of STA4. As a result, the TDLS discovery response action frame 1662 sent to the non-AP MLD 1622 over the direct link is accurately received by STA4 1626. In this way, communication over the direct link is successful. All subsequent data frames sent by STA5 to the non-AP MLD2 over the direct link will also be successful, as the RA can be accurately set to STA4 based on the mapping from STA-MLD2-IP to STA4-M in STA5's ARP cache.

[0142] Figure 17 shows a flowchart 1700 illustrating communication between a non-AP MLD1722 and a non-MLD STA1712 via AP MLD1702 for multilink address resolution, according to a fourth example of a second embodiment of the present disclosure.

[0143] This fourth example shows a legacy STA (e.g., STA5 1712) resolving the IPv6 address of a non-AP MLD (e.g., non-AP MLD2 1722) using a common link (e.g., Link 2 or the 6GHz frequency band). This fourth example is similar to the first example, except that STA5 1712 resolves an IPv6 address instead of an IPv4 address. STA5 1712 may initiate an ND query by generating a first data frame 1732 containing a broadcast address in its DA field 1735 and a neighbor solicitation message 1734, and sending it to AP MLD 1702 on the 6GHz link (frequency band). The broadcast address in the DA field 1735 indicates that the first data frame 1732 is being broadcast to all relevant APs and AP MLDs. The neighbor solicitation message includes the IP address of non-AP MLD2 1722 in the target IP field 1738, indicating that STA5 1712 is attempting to resolve the IP address to obtain the corresponding MAC address of non-AP MLD2 1722.

[0144] Next, AP2 1704 of AP MLD1702, receiving the first data frame 1732 on the 6GHz link, may forward the first data frame 1732', which includes the neighbor solicitation message 1734', to all relevant STAs and / or non-AP MLDs in the Basic Service Set (BSS), which includes STA5 1712 and non-AP MLD2 1722. The SA field 1735' contains the MAC address of STA5 1712, indicating that the original source of the first data frame 1732' is STA5 1712. Since the target IP addresses included in the target address field of the neighbor solicitation message 1734' do not match their respective L2 and MLD MAC IP addresses, STA5 1712 and AP2 1704 either ignore the neighbor solicitation message 1734' or reject it as a loopback frame.

[0145] On the other hand, the target IP address included in the target IP field 1738' of the neighbor solicitation message 1734' received by STA4 1724 matches the IP address of its non-AP MLD2 (STA-MLD2-IP). Therefore, STA4 1724 can confirm, based on the SA field 1735', that the neighbor solicitation message 1734' originates from STA5 1712, and may determine that the requesting device STA5 1712 is a non-MLD due to the absence of the "ML indication" in the first data frame 1732'. Based on this, the neighbor solicitation message 1734' is forwarded to the STA4 MAC SAP. The non-AP MLD2 1722 may also record link 2 (6GHz frequency band) as the operating link for STA5.

[0146] STA4 1724 may use its STA MAC SAP to generate a second data frame 1742 containing a neighbor advertisement message 1734, and send the second data frame 1742 to AP2 1704 via the operational link. The neighbor advertisement message 1744 contained within the second data frame 1742 includes the MAC address of STA4 (STA4-M) in the target L2 address field 1749.

[0147] Upon receiving the second data frame 1742, AP MLD 1702, based on the MAC address (STA5-M) in the DA field 1745, verifies that the neighbor advertisement message 1744 contained within the second data frame 1742 is directed to STA5, and forwards the second data frame 1742', including the neighbor advertisement message 1744', to STA5 1712 via AP2 1704, which is operating on STA5's operational link (link 2). It should be noted that the SA field 1745' of the second data frame 1742' is set to the MAC address of STA4 to identify that the original sending STA of the second data frame 1742 was STA4 1724.

[0148] Upon receiving the second data frame 1742, STA5 1712 may process it and update its ARP cache to map the IP address of the non-AP MLD (STA-MLD2-IP) in the target IP field 1748' of the neighbor advertisement message 1744' to the MAC address of STA4 (STA4-M) in the target L2 address field 1749'. As a result, the ND query is resolved.

[0149] Next, STA5 1712 may send the subsequent data frame (IP packet) 1752 to non-AP-MLD2 1722 via AP MLD 1702. The IP packet destined for STA-MLD2-IP will be addressed to STA-4 at the IP layer, with the DA field 1755 of IP packet 1752 set to the MAC address of STA4 1724 at the MLD level.

[0150] Upon receiving IP packet 1752, AP MLD1702 confirms that IP packet 1752 is destined for the STA (in this case, STA4 of non-AP MLD2 1722 based on DA field 1755) that is associated with the non-AP MLD, and forwards IP packet 1752' received from STA5 1712 to non-AP MLD2 1722 via one of the cooperating APs (in this case, AP2 1704 over the 6GHz link). Noting that non-AP MLD2 1722 is associated with AP MLD1702, and therefore AP MLD1702 knows the L2 MAC address of STA4 1724, AP MLD1702 sets the MAC address of STA4 (STA4-M) in RA field 1753' when forwarding IP packet 1752' to STA4 1724. In this way, IP packet 1752' will be accurately received by STA4 1724.

[0151] Based on SA field 1755', STA4 1724 confirms that data frame 1752' originates from STA5 1712, and due to the absence of the "ML indication" in data frame 1752', it may determine that the requesting device STA5 1712 is not MLD. Based on this, data frame 1752' is forwarded to STA4 MAC SAP.

[0152] Subsequently, STA5 1712 may send the ANQP request frame 1762 to STA4 1724 over the direct link, i.e., the operating link of STA5 (link 2). Based on the mapping stored in its ARP cache, STA5 1712 can set the RA field 1763 of the ANQP request frame 1762 to the MAC address of STA4 (STA4-M). In this way, the ANQP request frame 1762 sent by STA5 1712 to STA4 1724 over the direct link is accurately received. This solves the problem of frames transmitted between a legacy STA and a non-AP MLD over the direct link failing to be accurately received, as shown in Figure 9 in the first embodiment.

[0153] The following sections describe a third embodiment of this disclosure relating to multilink address resolution in AP MLD, non-AP MLD, and / or non-MLD STA using an MLD address query mechanism.

[0154] As described in the first embodiment, when a non-AP MLD resolves the IP address of another non-AP MLD, the ANQP request frames subsequently sent by the non-AP MLD to the other non-AP MLD on the direct link will fail because the RA is set to the MLD MAC address instead of the STA's MAC address.

[0155] According to a third embodiment of this disclosure, an MLD address query mechanism is proposed to resolve MLD MAC addresses to L2 MAC addresses in order to solve the above-mentioned problems.

[0156] A non-AP MLD or EHT STA may initiate an MLD MAC address query to request the peer non-AP MLD to provide its L2 MAC address (STA MAC address) after obtaining the peer non-AP MLD's MLD MAC address (for example, through an ARP / ND procedure as shown in Figure 8) and before initiating frame exchange on a direct link with the peer non-AP MLD. The non-AP MLD can recognize that the peer device is an MLD due to the presence of the ML indication. The non-AP MLD may initiate an MLD MAC address query by sending an MLD address query request frame to other related non-AP MLDs via an AP MLD (transparent or non-transparent). In particular, the MLD address query request frame would be transparent to the AP MLD if it is used so that the data frame contains the MLD address query, i.e., the AP MLD may not be aware of the contents 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 non-transparent.

[0157] Figure 18 shows a flowchart 1800 illustrating communication between AP MLD1802 and two non-AP MLDs 1812 and 1822 for multilink address resolution using management frames, according to a third embodiment of the present disclosure. In this example, STA2 1814 would want to initiate a direct link transmission with non-AP MLD2 1822, but due to the presence of ML indications in the ARP / ND query, it recognizes that the peer (non-AP MLD) is an MLD and the MAC address of non-AP MLD2, however STA2 1814 does not recognize the STAs that are working with non-AP MLD2 1822 and their STA MAC addresses. STA2 may send an MLD address query request frame 1832 to non-AP MLD2 via AP2 1804 of AP MLD1802 operating on link 2. The MLD address query request frame 1832 includes a target MLD MAC address field 1838 containing the MAC address of non-AP MLD2 1822, indicating non-AP MLD2 1822 as the target recipient of the MLD address query request frame 1832.

[0158] AP2 1804 of AP MLD1802, upon receiving the MLD address query request frame 1832, verifies that the MLD address query request frame 1832 is directed to the 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 the MLD address query request frame 1832' to non-AP MLD2 1822 using AP2 1804.

[0159] Since the MAC address contained in the target MAC address field 1838' of the MLD address query request frame 1832' received by STA4 1824 matches the MAC address of its non-AP MLD2 (STA-MLD2-M), non-AP MLD2 1822 may generate an MLD address query response frame 1842 containing an ML element 1849 with the L2 MAC addresses of all STAs working with non-AP MLD2 1822 and identifiers of the operational link, and send it back through AP2 1804 to the source, non-AP MLD1 1812, identified based on the source MAC address field 1839'.

[0160] AP2 1804 of AP MLD1802, upon receiving MLD address query response 1842, verifies 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 uses AP2 1804 to forward the MLD address query response frame 1842' to non-AP MLD1 1812.

[0161] STA2 1814 of non-AP MLD1 1812 may receive and process the MLD address query response frame 1842' and record the L2 MAC addresses and operating links of all STAs cooperating with non-AP MLD2 1822, for example, in the MLD address cache. Subsequently, STA2 1814 may send the ANQP request frame 1852 to STA4 1824 over the direct link (link 2). Based on the recorded L2 MAC address received in the MLD address query response frame 1842, STA2 1814 can set the RA field 1853 of the ANQP request frame 1852 to the L2 MAC address of STA4 (STA4-M). In this way, the ANQP request frame 1852 sent by STA2 1814 to STA4 1824 over the direct link is received accurately.

[0162] Figure 19 shows an 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. The MLD address query request frame 1900 comprises 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 dialog 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 may be grouped as a MAC header, and the category field 1902 and action field 1904, the dialog token field, the target MLD MAC address field 1906 and the source MAC address field 1908 may be grouped as 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 transmitting STA or the MLD MAC address of the transmitting MLD.

[0163] The MLD address query response frame 1920 comprises 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 dialog token field, a target MAC address field 1926 and an ML element and FCS. The frame control field, duration field, address 1 field, address 2 field, address 3 field, sequence control, and HT control field may be grouped as a MAC header, and the category field 1922 and action field 1924, the dialog token field, the target MAC address field 1926 and the ML element 1928 may be grouped as 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 target MAC address field 1926 is set to the MAC address of the source MAC address 1908 in the MLD address query request 1900.

[0164] The ML element 1928 further comprises a multilink control field having an element ID field, a length field, an element ID extension field, a type subfield 1930, and a presence bitmap subfield; a common information field having one or more MLD MAC address subfields; and one or more link information fields, each having a link ID subfield and one or more STA MAC address subfields. The type subfield 1930 of the multilink control field is set to correspond to an MLD address query type, and one or more STA MAC address subfields contained within 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 contains an identifier for the link on which the STA operates.

[0165] Alternatively, encapsulated data frames (e.g., Ethertype89-0d data frames containing a TDLS payload) may be used as MLD address query request and response frames. Figure 20 shows an example format of Ethertype89-0d data frames 2000, 2020 according to a third embodiment of the present disclosure.

[0166] An Ethertype89-0d data frame comprises 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 Subnetwork 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 field may be grouped as a MAC header, and the LLC field, SNA field, payload type field, and payload field may be grouped as a frame body. The SNA field 2002 is set to the Ethertype of 89-0d, and the payload type field 2004 is set to correspond to TDLS. The payload field 2006 comprises a category field 2008, a TDLS action field 2010, a dialog token field, a target 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 MLD MAC address of the sending STA or the MLD MAC address of the sending MLD.

[0167] As an alternative to the MLD address query request frame 1900, the Ethertype89-0d data frame 2000 comprises 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 subnetwork 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, and HT control field may be grouped as a MAC header, and the LLC field, SNAP field, payload type field, and payload field may be grouped as a frame body. The SNAP field 2002 is set to Ethertype 89-0d, and the payload type field 2004 is set to correspond to TDLS. The payload field 2006 comprises a category field 2008, a TDLS action field 2010, a dialog token field, a target MLD MAC address field 2012, and a source MAC address field 2014. The category field 2008 is set to correspond to a 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.

[0168] As an alternative to the MLD address query response frame 1920, the Ethertype89-0d data frame 2020 may contain the same frame as that in the Ethertype89-0d data frame used as the MLD address query request frame, except that the payload field 2022 comprises a category field 2024, a TDLS action field 2026, a dialog token field, a target MAC address field 2028, and an 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 target MAC address field 2028 is set to the MAC address of the source MAC address 2014 of the MLD address query request contained in the Ethertype89-0d data frame 2000. The ML element 2030 may have the same settings as the ML element 1928 in the MLD address query response frame 1920, as previously described and shown in Figure 19.

[0169] The following sections describe a fourth embodiment of this disclosure in which, with respect to multilink address resolution in AP MLD, non-AP MLD, and / or non-MLD STA, individual / group bits of their MAC addresses are used in the address field as an "ML indication" for multilink address resolution.

[0170] In the address field containing the MAC address of the transmit / transmit STA within the data and management frames, the individual / group bit (b0) of the MAC address is used as an "ML indication" to distinguish the L2 MAC address of the transmit / transmit STA from the MLD MAC address of the cooperating MLD. Figure 21 shows an example MAC address architecture 2100 according to a fourth embodiment of this disclosure. The MAC address consists of six octets. The first three octets 2102 are Organizationally Unique Identifiers (OUIs), and the last three octets 2104 are device-specific numbers known as Network Interface Controller (NIC) specifics. The first octet 2106 of the three OUI octets 2102 contains 8 bits b0-b7, with the b0 bit 2108, i.e., the least significant bit, being the individual / group bit. The individual / group (b0) bit 2108 can be set and used as an "ML indication". In particular, the b0 bit is set to 0 to indicate the L2 MAC address and to 1 to indicate the MLD MAC address. The b0 bit (individual / group bit) is also used to indicate "bandwidth signaling TA" within certain control frames, but not within data and management frames, and is therefore noteworthy for its use as "ML indication".

[0171] A non-AP MLD shall set the b0 bit to 1 in the TA field of the frame when it sends a frame to a peer device, and when an AP MLD relays a data frame sent by a non-AP MLD to another AP MLD, it shall set the b0 bit to 1 in the SA field of that data frame. Noting that the b0 bit is always set to 0 in data / management frames by pre-EHT STAs, b0 must not be set to 1 in frames addressed to (pre-EHT) legacy STAs or non-MLD EHT STAs.

[0172] If the b0 bit of the frame received from the peer device is set to 1, the receiving MLD is notified that the transmitting / outgoing device is an MLD, otherwise it is a legacy STA or a non-MLD EHT STA. The MLD must then recover its MLD MAC address by setting the b0 bit to 0, and may then take further action, such as forwarding to the correct MAC SAP, or attempting to resolve the peer MLD's L2 MAC address.

[0173] If the same MAC address is used for both the MLD MAC address and the L2 MAC address, then in both cases the same MAC address will be mapped to an IP address, so how the b0 bit is set is irrelevant.

[0174] In addition, a non-AP MLD may set the b0 bit to 1 in any address field containing its MLD MAC address (including address fields included in the data frame payload) when sending a frame to a peer device, for example, in the TDLS initiator / TDLS responder field in a TDLS discovery / setup frame. If the b0 bit is not set by the transmitting non-AP MLD, an AP MLD associated with the transmitting non-AP MLD may help set the b0 bit to 1 in an address field containing the transmitting MLD's MLD MAC address (including address fields included in the data frame payload) in a frame relayed by the AP to another non-AP MLD, for example, in the TDLS initiator / TDLS responder field in a TDLS discovery / setup frame.

[0175] In addition, if the b0 bit of the frame received from the peer device is set to 1, the receiving MLD's target application (TDLS) is notified that the transmitting / outgoing device is an MLD, or otherwise a legacy STA. The receiving MLD must restore its original MLD MAC address by resetting the b0 bit to 0. If the outgoing device is an MLD, the application may take further action, for example, by performing an MLD address query to request the peer MLD's STA MAC address.

[0176] According to this disclosure, the ARP / ND protocol for MLDs is "enhanced" to be MLD-aware. Advantageously, an MLD-aware ARP / ND protocol allows adaptive hardware resolution to function correctly, even if a single MLD MAC SAP is used for a legacy STA. Specifically, the ARP / ND protocol sets b0 to 1 in the source hardware address field of the transmitted 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 (known by the b0 bit in the source hardware address in the request frame being set to 1), the ARP / ND returns the MLD MAC address of the MLD as its hardware MAC address. If the requesting device is not an MLD (for example, known by the b0 bit in the source hardware address in the request frame being set to 0), ARP / ND will return the MAC address of the MLD's accompanying STA operating on the link from which the request frame was received as its hardware MAC address, and the MAC address of the MLD's accompanying STA may be provided to the ARP / ND protocol by the MLD in an ARP / ND message.

[0177] In addition, if the b0 bit is set to 1 in the resolved hardware address, ARP / ND is notified that the peer device is an MLD, and otherwise a legacy STA. The MLD needs to restore its original MLD MAC address by resetting the b0 bit to 0. However, since legacy ARP / ND may not understand that b0 is used as an ML indication and may record an incorrect MLD MAC address, the "enhanced" version of the ARP / ND protocol may only be used when all systems use the modified ARP / ND protocol.

[0178] Figure 22 shows a flowchart 2200 illustrating communication between AP MLD2202 and two non-AP MLD2212,2222 for multilink address resolution according to a fourth embodiment of the present disclosure.

[0179] This example shows 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). The STA2 2214 of non-AP MLD1 2212 may initiate an ARP query by generating a first data frame 2232 containing an ARP request 2234 and sending it to non-AP MLD2 2222 via AP2 2204 of AP MLD2202 on link 2 (6GHz frequency band). The ARP request 2234 includes a source hardware field 2236 containing the MAC address of non-AP MLD1 (STA-MLD1-M) with the b0 bit set to 1 as an "ML indication". When forwarding data frame 2232, the AP MLD may also set the b0 bit 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 target IP field 2239 of the first data frame 2232 matches the IP address of non-AP MLD2 2222, STA4 2224 generates a second data frame 2242 containing an ARP request 2244 and sends the data frame 2242 back to non-AP MLD1 2212 via AP2 2204. Because the requesting device is known to be an MLD due to the presence of the "ML indication", the generated ARP response 2242 has a source hardware field 2246 containing the MLD MAC address of non-AP MLD2 (STA-MLD2-M). In addition, the b0 bit of the MLD MAC address is set to 1 as the "ML indication" that non-AP MLD2 2222 is an MLD.

[0180] Upon receiving the second data frame 2242, STA2 2214 may process the MLD MAC address of the non-AP MLD2 in the source hardware field 2246 of the ARP response 2242, for example, by restoring the original MLD MAC address by resetting the setting of b0 to 0, and by mapping the IP address of the non-AP MLD2 (STA-MLD2-IP) in the source IP field 2247 to the MAC address of the non-AP MLD2 (STA-MLD2-M). As a result, the ARP query is resolved.

[0181] Next, non-AP MLD1 2212 may initiate TDLS discovery by sending a subsequent data frame 2252 containing a TDLS discovery request 2254 to non-AP MLD2 2222 through one of its cooperating 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 the b0 bit set to 1 as an "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 may also set the b0 bit of the SA field to 1 to indicate that the originating device is an MLD. The frame 2252 transmitted via AP MLD is accurately received by non-AP MLD2 2222.

[0182] In particular, non-AP MLD2 2222 recognizes that the peer device is an MLD due to the presence of an "ML indication" in the data frame containing the TDLS discovery request 2254, but does not know the STA MAC address of non-AP MLD1 2212. Therefore, before sending a TDLS discovery response action frame directly over the link in response to the TDLS discovery request 2254, non-AP MLD2 2222 sends an MLD address query request frame 2262 to non-AP MLD1 2212 via AP2 2204.

[0183] Since the target IP address contained in the target MAC address field 2268 of the MLD address query request frame 2262 received by STA2 2214 matches the MAC address of its non-AP MLD1 (STA-MLD1-M), STA2 2214 may generate an MLD address query response frame 2272 containing an ML element 2279 with the L2 MAC addresses (STA1-M and STA2-M) of all STAs working with the non-AP MLD1 2212, and send it back to the non-AP MLD2 2222.

[0184] STA4 2224 of non-AP MLD2 2222 receives and processes the MLD address query response frame 2272 to record the L2 MAC address and operating link of non-AP MLD1 2212, for example, in its MLD address cache. Subsequently, STA4 2224 may then send a TDLS discovery response action frame 2282 to STA2 2214 over the direct link (link 2). Based on the recorded L2 MAC address received in the MLD address query response frame 2272, STA4 2224 can accurately set the RA field 2283 of the TDLS discovery response action frame 2282 to the L2 MAC address of STA2 (STA2-M). In this way, this ensures that the TDLS discovery response action frame 2282 sent from STA4 2224 to STA2 2214 over the direct link is accurately received.

[0185] Figure 23 shows a flowchart illustrating communication between AP MLD2302, STA6 2312, and non-AP MLD 2322 for multilink address resolution according to a fourth embodiment of the present disclosure.

[0186] This example demonstrates an EHT non-MLD STA (e.g., STA6 2312) resolving the IPv4 address of a non-AP MLD (e.g., non-AP MLD2 2322). Again, this example assumes that the non-AP MLD2 2322 uses a single MLD MAC SAP for both MLD and non-MLD connections, i.e., it always returns the MLD MAC address as its hardware address.

[0187] STA6 2312 may initiate an ARP query by generating a first data frame 2332 containing an ARP request 2334 and sending it to non-AP MLD2 2332 via AP2 2304 of AP MLD2302 on link 2 (6GHz frequency band). The ARP request 2334 has a source hardware field 2336 containing the MAC address of STA6 (with the b0 bit remaining 0). STA4 2324 of non-AP MLD2 2322 receives the first data frame 2332 on link 2. Since the target 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 containing an ARP response 2344 and sends the data frame 2342 back to non-AP MLD1 2312 via AP2 2304. Similarly, the ARP response 2344 includes a source hardware field 2346 containing the MAC address of the non-AP MLD2 (STA-MLD2-M).

[0188] Upon receiving the second data frame 2342, STA6 2314 may process the MLD MAC address of the non-AP MLD2 in the source hardware field 2346 of the ARP response 2344 and update its ARP cache to map the IP address of the non-AP MLD2 (STA-MLD2-IP) in the source IP field 2347 to the MAC address of the non-AP MLD2 (STA-MLD2-M). As a result, the ARP query is resolved.

[0189] Next, the non-AP MLD2 2322 may initiate TDLS discovery by sending a subsequent data frame 2352 containing a TDLS discovery request 2354 to STA6 2312 through one of its cooperating STAs (in this case, from STA4 2324 through AP2 2304 on link 2 to STA6 2312). The TDLS discovery request 2354 includes a TDLS initiator field 2358 set in the MAC address of the non-AP MLD2 (STA-MLD2-M) with the b0 bit set to 1 as an "ML indication" to show that the non-AP MLD2 2222 is an MLD, and a TDLS responder field 2359 set in the MAC address of STA6 2312. The frame 2352 transmitted via the AP MLD is accurately received by STA6 2312.

[0190] In particular, STA6 2312 recognizes that the peer device is an MLD due to the presence of an "ML indication" in the data frame containing the TDLS discovery request, but does not know the exact STA MAC address of the non-AP MLD2 2322. Therefore, before sending a TDLS discovery response action frame in response to the TDLS discovery request 2354, STA6 2312 sends an MLD address query request frame 2362 to the non-AP MLD2 2322 via AP2 2304.

[0191] Since the target IP address contained in the target MAC address field 2368 of the MLD address query request frame 2362 received by STA4 2324 matches the MLD MAC address of non-AP MLD1 (STA-MLD2-M), STA4 2324 may generate an MLD address query response frame 2372 containing the L2 MAC addresses of all STAs (STA3-M and STA4-M) that are working with non-AP MLD2 2322, as well as an ML element 2379 containing an identifier for the operational link, and send it back to STA6 2312.

[0192] STA6 2312 may receive and process the MLD address query response frame 2372 and record the L2 MAC address and operating link of the non-AP MLD2 2322, for example, in its MLD address cache. Subsequently, STA6 2312 may then send the TDLS discovery response action frame 2382 to STA4 2324 over the direct link (link 2). Based on the recorded L2 MAC address received in the MLD address query response frame 2372, STA5 2312 may set the RA field 2383 of the TDLS discovery response action frame 2382 to the L2 MAC address of STA4 (STA4-M). In this way, this ensures that the TDLS discovery response action frame 2382 sent by STA6 2312 to STA4 2324 over the direct link is received correctly. Similarly, such a TDLS setup may allow for an additional data frame 2392 from STA4 2324 to STA6 2312 of non-AP MLD2 2322 over the direct link.

[0193] This example illustrates that even if an EHT STA (non-MLD) operates on a single link, it can operate correctly on a direct link with a non-AP-MLD that does not make special considerations for single-link devices (e.g., in response to an ARP request from a single-link device, it returns its MLD MAC address instead of its L2 MAC address). The EHT STA behaves this way thanks to its ability to utilize EHT features such as ML indications and MLD address queries, and with little assistance from the AP MLD (e.g., by setting the ML indication in the SA field of the forwarded frame). This specification also demonstrates that even if an MLD address query request frame is forwarded by the AP MLD on the wrong link, and then an MLD address response is sent by the non-AP MLD on the wrong link, the response frame is correctly received by the EHT STA, and the EHT STA is able to decode the AP MLD's beacon frame, etc., and find the link ID assigned to the different link, and thus extract the correct L2(STA) MAC address of the non-AP MLD based on the link ID.

[0194] The following section describes a fifth embodiment of this disclosure relating to multilink address resolution in AP MLDs with proxy ARP functionality, non-AP MLDs, and / or non-MLD STAs.

[0195] When AP MLD enables the proxy ARP service, AP MLD shall maintain hardware-to-Internet address mappings for each associated station (non-AP MLD and non-MLD STA), and shall upload the mappings when the Internet addresses of the associated stations change. When an IPv4 address resolved by an ARP request or ARP probe, or an IPv6 address resolved by a neighbor solicitation message, is used by a non-AP STA currently associated with the BSS, the proxy ARP service shall respond to the ARP request or ARP probe or neighbor solicitation message on behalf of that STA.

[0196] When an AP MLD receives an ARP request from a requesting station or DS, accompanied by the target IP address corresponding to the associated non-AP MLD, the AP MLD shall determine whether the requesting station is a non-AP MLD and (i) if the requesting station is a non-AP MLD or the request is from a DS, insert the MLD MAC address of the non-AP MLD as the source MAC address in 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 STA of the non-AP MLD operating on the link from which the request was received as the source MAC address in the ARP response packet.

[0197] Similarly, when an AP MLD receives a neighbor solicitation message from a requesting station or DS, accompanied by a target IP address corresponding to the associated non-AP MLD, the AP MLD shall determine whether the requesting station is a non-AP MLD and (i) if the requesting station is a non-AP MLD or the request is from a DS, insert the non-AP MLD's MLD MAC address as the source MAC address in 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 from which the request was received as the source MAC address in the neighbor advertisement message.

[0198] Furthermore, the AP MLD also sets the least significant bit b0 (individual / group bit) of the source MAC address to 1 in order to indicate the MLD MAC address in the ARP response packet or neighbor advertisement message sent on behalf of the associated MLD.

[0199] According to the fifth embodiment, when the proxy ARP function is enabled for the AP MLD, the AP MLD may also respond to MLD address query requests on behalf of the associated non-AP MLD or non-MLD STA. When the MLD MAC address being resolved in an MLD address query request is used by the non-AP MLD or non-MLD STA currently associated with the AP MLD, the proxy ARP service may respond to the MLD address query request on behalf of the non-AP MLD or non-MLD STA.

[0200] In particular, when an AP MLD receives an MLD address query request frame from a requesting station, along with the target MLD MAC address corresponding to the related non-AP MLD or non-MLD STA, the AP MLD shall construct an ML element containing the STA MAC addresses and operational link identifiers of all the related non-AP MLD's cooperating STAs, as well as the corresponding link IDs, and respond to the requesting station with an MLD address query response frame containing the ML element.

[0201] While it is natural for the MLD address query function to be packaged within the proxy ARP service, since MLD address query is a new feature in EHT, the AP MLD may enable the MLD address query function even if the proxy ARP service is not supported by the AP MLD, i.e., the function may be decoupled from the proxy ARP service. In addition, an AP MLD implementing the proxy ARP service may also implement the transmission of gratuitas ARP / unsolicited neighbor advertisements. A gratuitas ARP request is an ARP request packet in which both the source and destination IPs are set to the IP of the machine issuing the packet, and the destination MAC is the broadcast address ff:ff:ff:ff:ff:ff. Normally, no ARP response packet will occur. A gratuitas ARP response is a response to which no request was made. Similarly, an unsolicited neighbor advertisement is a message sent without anyone requesting it, i.e., without receiving a corresponding neighbor solicitation message. When enabled, AP MLDs may also send Gratuitas ARP packets or unsolicited neighbor advertisements that include the MLD MAC address of the associated non-AP MLD as the hardware address when the associated non-MLD's IP address or MLD MAC address changes. Typically, these are sent to a broadcast address or an all-host multicast address (ff02::1). These can cause associated legacy STAs to mistakenly upload their ARP cache with the MLD MAC address (instead of the STA MAC address). To prevent this, AP MLDs shall use unicast Gratuitas ARP or unicast unsolicited neighbor advertisement messages that include the correct STA MAC address as the source hardware address to each associated legacy STA after the broadcast Gratuitas ARP or multicast unsolicited neighbor advertisement. Alternatively, broadcast transmission of Gratuitas ARP / unsolicited neighbor advertisements is not implemented in EHT APs / AP MLDs.

[0202] Figure 24A shows a flowchart illustrating communication between a distribution system 2402, AP MLD2412, and a non-AP MLD2422 for multilink address resolution according to a fifth embodiment of the present disclosure.

[0203] This example shows AP MLD2412 resolving an ARP request from DS (e.g., PC2402) on behalf of the associated non-AP MLD (e.g., non-AP MLD1 2422). PC2402 may initiate an ARP query to resolve the IP address of non-AP MLD1 2422 associated with AP MLD2412 by generating an Ethernet frame 2432 containing ARP request 2434 and sending it to AP MLD2412 connected to PC2402 via Ethernet interface (I / F) 2404. ARP request 2434 has a source hardware field 2436 containing the PC's MAC address (PC-M) and a target IP field 2439 containing the IP address of non-AP MLD1 2422 (STA-MLD1-IP), indicating that PC2402 is attempting to resolve the IP address of non-AP MLD1 2422.

[0204] Since the target IP field 2439 of the first data frame 2432 matches the IP address of its associated non-MLD2 2422, AP MLD2412 may generate a second data frame 2442 containing the ARP response 2444, providing the MLD MAC address of non-AP MLD1 2422 (STA-MLD1-M) as its hardware address in the source hardware field 2446 of the ARP response 2444, and send the second data frame 2442 back to PC2402 via the Ethernet I / F 2404 through AP2 2414.

[0205] Upon receiving the second data frame 2442, PC2402 may process the MLD MAC address of the non-AP MLD1 contained in the source hardware field 2446 of the ARP response 2442 and update its ARP cache to map the IP address of the non-AP MLD1 in the source IP field 2447 to the MLD MAC address of the non-AP MLD1 (STA-MLD1-M). As a result, the ARP query is resolved without exchanging data frames with the non-AP MLD1 2422.

[0206] Next, PC2402 may wish to send the data to non-AP MLD1 2422 via AP MLD2412 by sending the subsequent Ethernet frame 2452 to AP MLD2412. Based on the mapping stored in its ARP cache, PC2402 can set the Dest. (destination) field of Ethernet frame 2452 to the MLD MAC address of non-AP MLD1. Upon receiving the subsequent Ethernet frame 2452, AP MLD2412 generates a corresponding data frame 2456, translates the MLD MAC address of non-AP MLD1, sets the MAC address of one of the linked STAs of non-AP MLD1 2422 (in this case, the MAC address of STA2 2424 (STA2-M)) in the RA field 2457 of data frame 2456, and forwards data frame 2456 to non-AP MLD1 2422. Since the RA field 2457 of data frame 2456 matches that of STA2 2424, data frame 2456 is accurately received by STA2 2424.

[0207] Figure 24B shows a flowchart illustrating communication between a distribution system 2402, AP MLD2404, and a non-MLD STA2426 for multilink address resolution according to a fifth embodiment of the present disclosure.

[0208] This example shows AP MLD2412 resolving an ARP request from DS (e.g., PC2402) on behalf of an associated non-MLD STA (e.g., STA5 2426). PC2402 may initiate an ARP query to resolve the IP address of the non-AP MLD1 2422 associated with AP MLD2412 by generating an Ethernet frame 2462 containing ARP request 2464 and sending it to AP MLD2412 connected to PC2402 via Ethernet interface (I / F) 2404. ARP request 2464 has a source hardware field 2466 containing the MAC address of the PC (PC-M) and a target IP field 2439 containing the IP address of STA5 2426 (STA5-IP), indicating that PC2402 is attempting to resolve the IP address of STA5 2426.

[0209] Since the target IP address 2469 of the first data frame 2462 matches the IP address of its associated STA5 2426, AP MLD2412 may generate a second data frame 2472 containing the ARP response 2474, providing the MLD MAC address of STA5 2426 (STA5-M) as its hardware address in the source hardware field 2476 of the ARP response 2474, and send the second data frame 2472 back to PC2402 via the Ethernet I / F2404 through AP2 2414.

[0210] Upon receiving the second frame 2472, PC2402 may process the MAC address of STA5 contained in the source hardware field 2476 of the ARP response 2444 and update its ARP cache to map the IP address of STA5 (STA5-IP) in the source IP field 2477 to the MAC address of STA5 (STA5-M). As a result, the ARP query is resolved without exchanging data frames with STA5 2426.

[0211] Next, PC2402 may wish to send the data to STA5 2426 via AP MLD2412 by sending the subsequent Ethernet frame 2482 to AP MLD2412. Based on the mapping stored in its ARP cache, PC2402 can set the Dest. field of Ethernet frame 2482 to the MAC address of STA5. Upon receiving the subsequent Ethernet frame 2482, AP MLD2412 may 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 that of STA5 2426, data frame 2486 is accurately received by STA5 2426.

[0212] Figure 25 shows a flowchart 2500 illustrating communication between AP MLD2502, non-AP MLD2 2522, and non-MLD STA2512 for multilink address resolution, according to a first example of a fifth embodiment of the present disclosure.

[0213] In this first example, an AP MLD is shown resolving a neighbor request message from a non-MLD STA (e.g., STA5 2512) on behalf of a non-AP MLD (e.g., non-AP MLD2 2522).

[0214] STA5 2512 may initiate an ND query by generating a first data frame 2532 containing a neighbor solicitation message 2534 and sending it to AP MLD2502 on link 2 (6GHz frequency band). The neighbor solicitation message 2534 contains the IP address of the non-AP MLD2 2522 in the target address field 2568, indicating that STA5 2512 is attempting to resolve the IP address to obtain the corresponding MAC address of the non-AP MLD2 2522.

[0215] Next, AP2 2504 of AP MLD2502, having received the first data frame 2532 on the 6GHz link, may, based on the source L2 address field of the neighbor solicitation message 2534, verify that the requesting STA (i.e., STA5 2512) is a legacy STA and that the target IP address included in the target address field 2538 of the neighbor solicitation message 2534 matches the address of its associated non-AP MLD2 2522 IP. Therefore, AP2 2504 may generate a second data frame 2542 containing a neighbor advertisement message 2544, providing the STA MAC address of the non-AP MLD2 2522 (STA4-M) corresponding to the link of STA5 (i.e., link 2) as its hardware address in the target L2 address 2549 of the neighbor advertisement message 2544, instead of the MLD MAC address, and send the second data frame 2542 back to STA5 2512 via AP2 2504 through the operating link of STA5.

[0216] Since a non-AP MLD (e.g., non-AP MLD2 2522) contains multiple STA MAC addresses, it is noteworthy that, as long as there is a common link between the legacy STA requesting address resolution (e.g., STA5 2512) and the target non-AP MLD, the AP MLD will return the STA MAC address of the collaborating STA of the non-AP MLD operating on the common link as the non-AP MLD's hardware address (target L2 address). This will ensure that the legacy STA and the non-AP MLD can communicate directly over the link (common link). However, if there is no common link between the legacy STA and the non-AP MLD, the AP MLD may return either the non-AP MLD's MLD MAC address or the MAC address of the collaborating STA as the non-AP MLD's hardware address (target L2 address).

[0217] STA5 2512, receiving the second data frame 2542 sent by AP MLD2502 on behalf of non-AP MLD2 2522, may process the STA MAC address contained within the target L2 address 2549 of the neighbor advertisement message 2544 and update its neighbor cache to map the IP address of non-AP MLD2 in the target address field 2548 (STA-MLD2-IP) to the L2 MAC address in the target L2 address field 2549 (STA4-M). As a result, the ND query is resolved without exchanging the data frame with non-AP MLD2 2522.

[0218] Next, STA5 2512 may initiate TDLS discovery by sending a subsequent data frame 2552 containing a TDLS discovery request 2554 to non-AP MLD2 2522 via AP MLD2502. 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 in the TDLS responder field 2559 of the TDLS discovery request 2554 (DA field = TDLS responder field).

[0219] AP2 2504 of AP MLD2502 may forward data frame 2552 to STA4 2524, after confirming, based on the STA MAC address, that the subsequent data frame 2552 is destined for STA4 2524 of its associated non-AP MLD2 2522. AP MLD2502 may set its RA field 2553 before forwarding data frame 2552 to STA4 2524. In this way, data frame 2552 is accurately received by the non-AP MLD2 2522 via AP MLD2502.

[0220] Non-AP MLD2522 may respond by sending a TDLS discovery response action frame 2562 over the direct link (link 2), where the TA field 2563 and TDLS responder field 2569 are set to the STA MAC address of the cooperating STA (in this case, STA4 2524) that is sending the TDLS discovery response action frame 2562.

[0221] Furthermore, since both the TDLS responder field 2569 and the TA field 2563 within the link identifier element of the TDLS discovery response action frame 2562, which is relayed and sent over the direct link, are set to the same STA MAC address (STA4-M), there is no confusion in the receiving legacy STA (STA5 2512). This effectively resolves the second address mismatch problem when a legacy STA initiates a TDLS setup with a non-AP MLD without needing to change the RA / TA setting rules or using the MLD MAC address in the TDLS initiator or TDLS responder field.

[0222] In addition, since not only the TDLS responder field but also the DA is set to the peer device's STA MAC address (STA4-M) here, AP MLD2502 can accurately identify the link (link 2) that should be used to forward the TDLS discovery / setup request frame to the non-AP MLD2 2522, and therefore, the link crossover problem does not occur.

[0223] Next, STA5 2512 may initiate TDLS setup with STA4 2524 via AP MLD2502 by sending a further data frame 2572 containing TDLS setup request 2574 to AP MLD2502. The STA MAC address (STA4-M) of the non-AP MLD2 2522 stored in the neighbor cache is used not only to set the TDLS responder field 2579 of TDLS setup request 2574, but also to set the DA field 2576 of data frame 2572 (DA = TDLS responder).

[0224] AP2 2504 of AP MLD2502 may forward the additional data frame 2572 to STA4 2524, after confirming, based on the STA MAC address, that the additional data frame 2572 is destined for STA4 2524 of its associated non-AP MLD2 2522. Before forwarding the data frame 2572 to STA4 2524, AP MLD2502 may set its RA field 2553 to the STA MAC address (STA4-M) of the non-AP MLD2 2522 corresponding to the STA5 link (i.e., link 2). In this way, the data frame 2572 is accurately received by the non-AP MLD2 2522 via AP MLD2502.

[0225] Non-AP MLD2522 may respond by sending another data frame 2582 over the direct link (link 2) containing a TDLS setup response 2584, where the DA field 2586 and the TDLS initiator field 2588 are set to the MAC addresses in the TDLS initiator field 2578 of the TDLS setup request 2574. In this way, the TDLS between STA4 2524 and STA5 2512 is successfully set up, and the non-MLD STA (STA5 2512) and the non-AP MLD STA (STA4 2524 of non-AP MLD2 2522) can appropriately set the RA field 2593 of data frame 2592 as the STA MAC addresses (STA4-M and STA5-M), so that data frame 2592 can be sent and received from each other over the direct link.

[0226] Figure 26 shows a flowchart 2600 illustrating communication between AP MLD2602 and two non-AP MLD2612,2622 for multilink address resolution, according to a second example of a fifth embodiment of the present disclosure.

[0227] This second example shows AP MLD2602 resolving ARP requests and MLD address query requests from a non-AP MLD (e.g., non-AP MLD1 2612) on behalf of another non-AP MLD (e.g., non-AP MLD2 2622).

[0228] The STA2 2614 of the non-AP MLD1 2612 may initiate an ARP query by generating a first data frame 2632 containing an ARP request 2634 and sending it to the non-AP MLD2 2622 via AP MLD2602 on link 2 (6GHz frequency band). The ARP request 2634 comprises a source hardware field 2636 containing the MAC address of the non-AP MLD1 (STA-MLD1-M) and a target IP field 2639 containing the IP address of the non-AP MLD2 (STA-MLD2-IP), indicating that the non-AP MLD1 2612 is attempting to resolve the IP address to obtain the corresponding MAC address of the non-AP MLD2 2622.

[0229] Next, AP2 2604 of AP MLD2602, receiving the first data frame 2632 on the 6GHz link, may, based on the source hardware field 2636 of the ARP request 2634, verify that the requester (i.e., non-AP MLD1 2612) is an MLD and that the target IP address included in the target IP field 2639 of the ARP request 2634 matches the IP address of its associated non-AP MLD2. Therefore, AP MLD2602 may generate a second data frame 2642 containing the ARP response 2644, providing the MLD MAC address of non-AP MLD2 2622 (STA-MLD2-M) as its hardware address in the source hardware field 2646 of the ARP response 2644, and further 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.

[0230] Upon receiving the second data frame 2642, non-AP MLD1 2612 processes the ARP response and recognizes that the MAC address contained in the source hardware field 2646 is an MLD MAC address due to the presence of the ML indication in the b0 bit. Non-AP MLD1 2612 may then update its ARP cache to map the IP of non-AP MLD2 (STA-MLD2-IP) in the source IP field 2647 to the MLD MAC address of non-AP MLD2 (STA-MLD2-M) in the source hardware field 2646 by restoring the original MLD MAC address by resetting the b0 bit to 0. As a result, the ARP query is resolved and STA2 2614 now recognizes that STA-MLD2-M is an MLD MAC address without exchanging data frames with non-AP MLD2 2622 due to the presence of the ML indication.

[0231] Non-AP MLD1 2612 recognizes that non-AP MLD2 2622 is an MLD based on the ML indication in the b0 bit of its MLD MAC address, and therefore non-AP MLD1 2612 initiates an MLD address query to obtain the STA MAC 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 MLD2602.

[0232] AP MLD2602 may resolve the MLD MAC address on behalf of non-AP MLD2 2622 by generating an MLD address query response that returns to non-AP MLD1 2612, which includes an ML element 2669 containing the L2 MAC addresses of all STAs (STA3-M and STA4-M) interacting with non-AP MLD2 2622, as well as the identifier of the operational link, after confirming from the target MLD MAC address corresponding to the associated non-AP MLD (in this case, non-AP MLD2 2622).

[0233] STA2 2614 of non-AP MLD1 2612 may receive and process the MLD address query response frame 2662 and record the L2 MAC addresses of all STAs cooperating with non-AP MLD2 2622, for example, in its MLD address cache. Subsequently, STA2 2614 may send an ANQP request frame 2672 to STA4 2624 over the direct link (link 2). Based on the recorded L2 MAC addresses received in the MLD address query response frame 2662, STA2 2614 can set the RA field 2673 of the ANQP request frame 2672 to the L2 MAC address of STA4 (STA4-M). In this way, the ANQP request frame 2672 sent by STA2 2614 to STA4 2624 over the direct link is received accurately.

[0234] Figure 27 shows a flowchart 2700 illustrating communication between AP MLD2702, non-AP MLD2712, and non-MLD STA2722 for multilink resolution, according to a third example of a fifth embodiment of the present disclosure.

[0235] This third example shows AP MLD2702 resolving ARP requests from a non-AP MLD (e.g., non-AP MLD2 2712) on behalf of a legacy STA (e.g., STA5 2722).

[0236] STA4 2714 of non-AP MLD2 2712 may initiate an ARP query by generating a first data frame 2732 containing an ARP request 2734 and sending it to STA5 2722 via AP MLD2702 on link 2 (6GHz frequency band). The ARP request 2734 comprises a source hardware field 2736 containing the MAC address of the non-AP MLD2 (STA-MLD2-M) and a target IP field 2739 containing the IP address of STA5 (STA5-IP), indicating that the non-AP MLD2 2712 is attempting to resolve an IP address to obtain the corresponding MAC address of STA5 2722.

[0237] Next, AP2 2704 of AP MLD2702, having received the first data frame 2732 on the 6GHz link, may, based on the source hardware field 2736 of the ARP request 2734, verify that the requester (i.e., non-AP MLD2 2712) is an MLD and that the target IP address included in the target IP field 2739 of the ARP request 2734 matches the IP address of its associated STA5. Therefore, AP MLD2702 may generate a second data frame 2742 containing the ARP response 2744, providing the L2 MAC address of the STA5 (STA5-M) as its hardware address in the source hardware field 2746 of the ARP response 2744 (the b0 bit of the MAC address remained 0), and send the second data frame 2742 back to non-AP MLD2 2712.

[0238] Upon receiving the second data frame 2742, non-AP MLD2 2712 processes the ARP response 2744 and recognizes that, due to the absence of an ML indication in the b0 bit, the MAC address contained in the source hardware field 2746 is an STA MAC address and not an MLD MAC address. Non-AP MLD1 2712 may update its ARP cache to map the IP address of STA5 in the source IP field 2747 (STA5-IP) to the L2 MAC address of STA5 in the source hardware field 2746 (STA5-M). As a result, the ARP query is resolved and STA4 2714 now recognizes that STA5 is a non-MLD or legacy STA without exchanging data frames with STA5 2722.

[0239] Advantageously, STA5 2722 never receives ARP request 2732, and therefore does not perform opportunistic ARP cache updates for non-AP MLD2 2712, thus avoiding the address mismatch problem.

[0240] Next, the non-AP MLD2 2712 may initiate TDLS discovery by generating a subsequent data frame 2752 containing a TDLS discovery request 2754 to STA5 2722 via AP MLD2702. Since it recognizes that STA5 is a non-MLD or legacy STA, the STA MAC address (STA4-M) of one of its cooperating STAs is used in the TDLS initiator field 2758.

[0241] AP2 2704 of AP MLD2702 may forward data frame 2752' to STA5 2722 after confirming, based on the STA MAC address, that the subsequent data frame 2752 is directed to STA4 2714 of its associated non-AP MLD2 2712. AP MLD2502 may correct its SA field 2755' to the MAC address of STA4 (STA4-M) before forwarding data frame 2752' to STA5 2722. Data frame 2752 can still be received accurately by STA5 2722.

[0242] Since both the TDLS initiator field 2758' and the SA field 2755' within the link identifier element of the TDLS discovery request frame 2752' relayed by the AP are set as the STA MAC address, there should be no confusion at the receiving peer STA. This effectively resolves the first address mismatch problem raised in the IEEE submission (IEEE 802.11-2 / 1692r2) without requiring a change in the RA / TA setting rules or using the MLD MAC address in the TDLS initiator or TDLS responder field when a non-AP MLD initiates a TDLS setup with a legacy STA.

[0243] STA5 2722 may respond by sending a TDLS discovery response action frame 2762 over the direct link (link 2), where the TA field 2765 and the TDLS responder field 2769 are set to its own STA MAC address. STA5 2722 may then set the RA field to the L2 MAC address of STA4 based on the TDLS initiator field 2758' of the received data frame 2752'.

[0244] Next, STA5 and STA4 may perform TDLS setup (not shown) by exchanging TDLS setup request / response frames in the same manner as described in Figure 26. Once TDLS setup is performed, STA5 2722 and STA4 2714 (non-AP MLD2 2712) can accurately set the RA fields 2773 and 2783 of data frames 2772 and 2782 as STA MAC addresses (STA4-M and STA5-M), respectively, so that data frames 2772 and 2782 can be successfully sent and received directly over the link.

[0245] 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 it is notified that the target STA is a legacy STA (for example, due to the absence of an ML indication in the ARP response), the non-AP MLD cannot be certain that the legacy STA is operating on which link. When the non-AP MLD initiates TDLS discovery with the legacy STA, it may select the wrong link, thereby potentially using the wrong STA MAC address (e.g., STA3-M) in the TDLS initiator field of the TDLS discovery frame. As a result, if the legacy STA uses the TDLS initiator field to set the RA field of the TDLS discovery response action frame sent over the direct link, the non-AP MLD2 will fail to receive the frame.

[0246] Figure 28 shows a flowchart 2800 illustrating communication between AP MLD2802, non-AP MLD2812, and non-MLD STA2822 for multilink resolution, according to a fourth example of a fifth embodiment of the present disclosure.

[0247] This fourth example shows AP MLD2802 resolving ARP requests from a non-AP MLD (e.g., non-AP MLD2 2812) on behalf of a legacy STA (e.g., STA5 2822).

[0248] The STA3 2814 of the non-AP MLD2 2812 may initiate an ARP query by generating a first data frame 2832 containing an ARP request 2834 and sending it to the STA5 2822 via the AP MLD2802 on a different link from the operating link of the STA5 (in this case, link 1 or the 5GHz frequency band). The ARP request 2834 comprises a source hardware field 2836 containing the MAC address of the non-AP MLD2 (STA-MLD2-M) and a target IP field 2839 containing the IP address of the STA5 (STA5-IP), indicating that the non-AP MLD2 2812 is attempting to resolve an IP address to obtain the corresponding MAC address of the STA5 2822.

[0249] Next, AP1 2804 of AP MLD2802, having received the first data frame 2832 on the 5GHz link, may, based on the source hardware field 2836 of the ARP request 2834, verify that the requester (i.e., non-AP MLD2 2812) is an MLD and that the target IP address included in the target IP field 2839 of the ARP request 2834 matches the IP address of its associated STA5. Therefore, AP MLD2802 may generate a second data frame 2842 containing the ARP response 2844, providing the L2 MAC address of the STA5 (STA5-M) as its hardware address in the source hardware field 2846 of the ARP response 2844 (the b0 bit of the MAC address remains 0), and send the second data frame 2842 back to non-AP MLD2 2812.

[0250] Upon receiving the second data frame 2842 over link 1 via STA3 2814, the non-AP MLD2 2812 processes the ARP response 2844 and recognizes that, due to the absence of an ML indication in the b0 bit, the MAC address contained in the source hardware field 2846 is the STA MAC address and not the MLD MAC address. The non-AP MLD2 2812 may update its ARP cache to map the IP address of STA5 in the source IP field 2847 (STA5-IP) to the L2 MAC address of STA5 in the source hardware field 2846 (STA5-M). As a result, the ARP query is resolved.

[0251] Next, the non-AP MLD2 2812 may initiate TDLS discovery by generating a subsequent data frame 2852 containing a TDLS discovery request 2854 to STA5 2822 via AP MLD2802, using an incorrect link, i.e., a link on which STA5 2822 does not operate. This is because, since STA5 is recognized as a non-MLD or legacy STA, the STA MAC address of STA3 2814 operating on 5GHz is used in the TDLS initiator field 2858, but that STA MAC address is inadvertently an incorrect address (STA3-M).

[0252] AP MLD2802 may, based on the STA MAC address, confirm that the subsequent data frame 2852 is directed to STA5 2822, set the SA field 2855' of data frame 2852' to the TDLS initiator to the exact STA MAC address (STA4-M) of STA4 2816 operating on the STA5 operating link, and forward data frame 2852' to STA5 2822 via AP2 2802 over the correct link (6GHz frequency band). In this way, data frame 2852 is accurately received by STA5 2822.

[0253] STA5 2822 may respond by sending a TDLS discovery response action frame 2862 over the direct link (link 2), where the TA field 2865 and TDLS responder field 2869 are set to its own MAC address, but the RA field 2863 is set as the MAC address of the wrong link (STA3-M) based on the TDLS initiator field 2858' of the received data frame 2852'. In this way, data frame 2862 over the direct link between STA5 2822 and STA4 2816 fails due to the wrong RA.

[0254] To avoid potential mismatches caused by crossover issues, AP MLDs can assist non-AP MLDs by ensuring that ARP responses sent on behalf of legacy / non-MLD STAs are always sent on the same link, as long as the non-AP MLD operates on that link. Non-AP MLDs are notified that the peer STA is a legacy / non-MLD STA due to the absence of an "ML indication" in the data frame containing the ARP response. Non-AP MLDs are implicitly notified of the operating link of the legacy / non-MLD STA based on the link on which the ARP response was received, thereby avoiding crossover issues caused by incorrect TDLS initiator addresses.

[0255] Figure 29 shows a flowchart 2900 illustrating communication between AP MLD2902, non-AP MLD2912, and non-MLD STA2922 for multilink resolution, according to a fifth example of a fifth embodiment of the present disclosure.

[0256] This fifth example shows AP MLD2902 resolving ARP requests from a non-AP MLD (e.g., non-AP MLD2 2912) on behalf of a legacy STA (e.g., STA5 2922).

[0257] The STA3 2914 of the non-AP MLD2 2912 may initiate an ARP query by generating a first data frame 2932 containing an ARP request 2934 and sending it to the STA5 2922 via AP MLD2902 on a different link from the operating link of the STA5 (in this case, link 1 or the 5GHz frequency band). The ARP request 2934 comprises a source hardware field 2936 containing the MAC address of the non-AP MLD2 (STA-MLD2-M) and a target IP field 2939 containing the IP address of the STA5 (STA5-IP), indicating that the non-AP MLD2 2912 is attempting to resolve an IP address to obtain the corresponding MAC address of the STA5 2922.

[0258] Even if ARP request 2934 is received on a link different from the legacy STA's operating link (link 2), AP MLD 2902, upon receiving the first data frame 2932, may, based on the source hardware field 2936 of ARP request 2934, verify that the requester (i.e., non-AP MLD2 2912) is an MLD and that the target IP address included in the target IP field 2939 of ARP request 2934 matches the IP address of its associated STA5. Therefore, AP MLD 2902 may intentionally generate a second data frame 2942 and send back ARP response 2944 to non-AP MLD2 2912 via AP2 2906 on the link on which the target STA (STA5 2922) operates (i.e., link 2), providing the STA5's L2 MAC address (STA5-M) as its hardware address in the source hardware field 2946 of ARP response 2944.

[0259] Upon receiving the second data frame 2942 over link 2 via STA4 2916, the non-AP MLD2 2912 may process the ARP response 2944 and recognize that, due to the absence of an ML indication in the b0 bit, the MAC address contained in the source hardware field 2946 is the STA MAC address and not the MLD MAC address. The non-AP MLD2 2912 may update its ARP cache to map the IP address of STA5 in the source IP field 2947 (STA5-IP) to the L2 MAC address of STA5 in the source hardware field 2946 (STA5-M). As a result, the ARP query is resolved. Furthermore, the non-AP MLD2 2912 records link 2 as the operating link for STA5 based on the link on which the ARP response 2944 is received.

[0260] Next, the non-AP MLD2 2912 may initiate TDLS discovery by generating a subsequent data frame 2952 containing a TDLS discovery request 2954 to STA5 2922 via AP MLD2902 on the correct link (link 2), i.e., the operating link of STA5. Since it recognizes that STA5 is a non-MLD or legacy STA, the exact STA MAC address (STA4-M) of the non-AP MLD2912 is used as the TDLS initiator field 2958 of the TDLS discovery request 2954 in the subsequent data frame 2952.

[0261] AP MLD2902 may, based on the STA MAC address, confirm that the subsequent data frame 2952 is destined for STA5 2922 and forward data frame 2952 to STA5 2922. AP MLD2902 will set the SA field 2955' of data frame 2952' to the MAC address of STA4 (STA4-M) and forward data frame 2952' to STA5 2922 over the correct link. In this way, data frame 2952 can also be accurately received by STA5 2922.

[0262] STA5 2922 may respond by sending a TDLS discovery response action frame 2962 over the direct link (link 2), with the TA field 2965 and TDLS responder field 2969 set to its own STA MAC address. Based on the TDLS initiator field 2958' of the received data frame 2952', STA5 2922 may set the RA field 2963 to the MAC address of the correct link (STA4-M), and the TDLS discovery response action frame 2962 will be accurately received by STA4 2916.

[0263] As a result, STA5 2922 and STA4 2916 (non-AP MLD2 2912) can accurately set the RA fields 2973 and 2983 of data frames 2972 ​​and 2982 as appropriate STA MAC addresses (STA5-M and STA4-M), allowing them to directly send and receive each other's data frames 2972 ​​and 2982 over the link.

[0264] Figure 30 shows a flowchart 3000 illustrating communication between an AP MLD 3002, a non-AP MLD 3012, and a non-MLD STA 3022 for multilink resolution, according to a sixth example of a fifth embodiment of the present disclosure. The sixth example is a continuation of the fourth example shown in Figure 28, in which the original TDLS discovery request frame is sent over the wrong link using the wrong TDLS initiator address. In this sixth example, with respect to the AP MLD 3002, a non-AP MLD (e.g., non-AP MLD2 3012), and a legacy STA (e.g., STA5 3022), a clear solution to the crossover issued in the fifth example of the fifth embodiment of the present disclosure for discovering the operational link of the non-MLD STA is shown through the use of an MLD address query mechanism. In this sixth example, the MLD address query mechanism is used not 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 could also try groping its way to another link to retry the TDLS discovery request if it fails to receive the TDLS discovery response action frame.

[0265] After sending subsequent dataframes including APR queries and TDLS discovery requests, STA5 3022 may send a TDLS discovery response action frame to STA4 3016 on the direct link that contains an incorrect RA field 3033 based on the TDLS initiator field in the TDLS discovery request (not shown in Figure 30) (for example, set to the STA MAC address (STA3-M) of STA3 3014). As a result, all frames on the direct link will fail due to the incorrect RA.

[0266] Due to the failure to receive the TDLS discovery response action frame 3032 from STA5 3022 on the direct link, the non-AP MLD2 3012 may infer that the TDLS discovery request frame may have been sent on the wrong link. The non-AP MLD2 3012 may send the MLD address query request frame 3042 to STA5 3022 via AP2 3004 of AP MLD3002. Upon receiving the MLD address query request frame 3042, AP MLD3002 may confirm that the MAC address contained in the target MLD MAC address field 3048 of the MLD address query request frame 3042 matches the MAC address of its associated STA5, and that the non-AP MLD2 is attempting to resolve the IP address to obtain the corresponding MAC address and operating link of STA5 3022. Therefore, AP MLD3002 may generate an MLD address query response frame 3052 to provide such information to a non-AP MLD2 3012 on behalf of STA5 3022. In particular, the MLD address query response frame 3052 comprises an ML element that includes a single link information field having a link ID subfield 3059a with a value of 2, indicating that the operating link of the target STA is link 2, and an address field 3059b indicating the MAC address of the target STA, i.e., STA5 3022.

[0267] After receiving information about the correct link for transmitting the data frame, the non-AP MLD2 may restart TDLS discovery by sending a data frame 3062 containing a TDLS discovery request 3064 to STA5 3022 via AP MLD 3002 on the correct (given) link received 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.

[0268] Based on the STA MAC address within the TDLS responder field 3069, AP MLD3002 may confirm that the data frame 3062 is directed to STA5 3022 and transfer it to STA5 3022. To indicate the source of the data frame 3062’, AP MLD3002 will set the SA field 3065’ of the data frame 3062’ to the MAC address of STA4 (STA4-M). In that way, the data frame 3062 is accurately received by STA5 2922 via AP MLD3002.

[0269] Next, in response, STA5 3022 may send a TDLS discovery response action frame 3072 to STA4 3016 of non-AP MLD3012 via the direct link (Link 2). STA5 3022 can accurately set the MAC address of STA4 within the RA field 3073. In that way, since the RA fields 3073, 3083 are accurately set as the MAC address of the STA, the TDLS discovery response action frame 3072 and any subsequent data frames 3072 from STA5 3022 to STA4 3016 on the direct link are accurately received by STA4.

[0270] The present disclosure shows the following, namely, (i) the IP address of the MLD is dynamically mapped to either one of the MLD MAC address or the L2 MAC address of the MLD. If the requesting station is the MLD, the MLD MAC address is returned as the hardware MAC address of the MLD, and if the requesting station is not the MLD (either an EHT or a legacy STA), the MAC address of the associated AP / STA operating on the link where the ARP request or neighbor solicitation was received is returned as the hardware MAC address of the MLD, (ii) frames transmitted by the MLD include an "ML indication" to indicate that it is transmitted (or originated) by the MLD, (iii) an MLD address query mechanism is proposed to resolve from the MLD MAC address to the L2 MAC address, (iv) proxy ARP dynamically maps the MAC address of the associated station to either one of the MLD MAC address or the L2 MAC address of the MLD depending on whether the requesting station is the MLD or not, and proxy ARP also responds to the MLD address query request and sets the "ML indication" in the ARP / ND response on behalf of the associated non-AP MLD, and (v) the AP MLD simply forwards the ARP / ND response received from the associated MLD within the same BSS where the non-MLD STA addressed in the DA operates.

[0271] Figure 31 shows an example configuration of a communication device 3100 and two communication devices 3102 and 3104 that work in conjunction with the communication device 3100. The communication device 3100 is implemented as an AP MLD, and each of the cooperating communication devices 3102 and 3104 may be implemented as an AP configured for multilink address resolution according to this disclosure. The communication device 3100 further comprises 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 further comprises an MLD MAC SAP 3110 used to communicate with the Internet Layer, each comprising an ARP module 3114 and an ICMP module 3116 for generating and processing frames for ARP and ND queries, respectively. Each of the communication devices 3102 and 3104, which are linked to the communication device, provides a link to other external communication devices and / or distribution systems (DS), and is associated with them and capable of sending and receiving signals to and from them. Each linked communication device 3102 and 3104 comprises a MAC layer and a PHY (physical) layer. The MAC layer includes a storage module 3121 that stores its AP MAC address and an optional AP MAC SAP 3124 for direct communication with the Internet layer for traffic to and from legacy STAs. The PHY layer connects to a radio transmitter, radio receiver, and antenna used to send and receive signals to and from other communication devices via the corresponding link 3118.

[0272] According to this disclosure, traffic to and from a DS (including ARP and ND messages) from / to an MLD is routed through the MLD MAC SAP 3110, as indicated by line 3126, while traffic to and from a DS (including ARP and ND messages) that is not MLD is routed through the AP MAC SAP 3124, as indicated by line 3128. The ARP / ND returns the MAC address of the corresponding MAC SAP that the ARP / ND received through it.

[0273] Figure 32 shows an example configuration of a communication device 3200 and two communication devices 3202 and 3204 that work in conjunction with the communication device 3200. The communication device 3200 is implemented as a non-AP MLD, and each of the cooperating communication devices 3202 and 3204 may be implemented as an STA configured for multilink address resolution according to this disclosure. The communication device 3200 further comprises a storage module 3201 for storing its MLD MAC address and a function module 3206 for generating and processing MLD address query-related services. The communication device 3200 further comprises an MLD MAC SAP 3210 used to communicate with the Internet Layer, each having an ARP module 3214 and an ICMP module 3216 for generating and processing frames for ARP and ND queries. Each of the communication devices 3202 and 3204 working in conjunction with the communication device can provide links to other external communication devices / devices and be associated with them to send and receive signals to and from them. Each collaborative communication device 3202, 3204 comprises a MAC layer and a PHY (physical) layer. The MAC layer includes a memory module 3221 that stores its STA MAC address and an optional STA MAC SAP 3210 for direct communication with the Internet layer for traffic to / from legacy STAs. The PHY layer connects to radio transmitters, radio receivers, and antennas used to send and receive signals to / from other communication devices via the corresponding link 3218.

[0274] According to this disclosure, traffic to and from a DS (including ARP and ND messages) from / to an MLD is routed through the MLD MAC SAP 3210 as indicated by line 3226, while traffic to and from a DS (including ARP and ND messages) that is not MLD is routed through the STA MAC SAP 3210 as indicated by line 3228. The ARP / ND returns the MAC address of the corresponding MAC SAP that the ARP / ND received through it.

[0275] This disclosure can be implemented by software or software in conjunction with hardware. Each functional block used in the description of each embodiment above can be implemented partially or entirely by an LSI, for example, an integrated circuit, and each process described in each embodiment may be controlled partially or entirely by the same LSI or a combination of multiple LSIs. The LSI may be formed individually as multiple chips, or a single chip may be formed to include some or all of the functional blocks. The LSI may include data inputs and outputs coupled thereto. In this specification, LSIs may be referred to as ICs, system LSIs, super LSIs, or ultra LSIs depending on the degree of integration. However, the techniques for implementing integrated circuits are not limited to LSIs and may be implemented using dedicated circuits, general-purpose processors, or dedicated processors. In addition, FPGAs (field-programmable gate arrays) that can be programmed after the manufacture of the LSI, or reconfigurable processors that can reconfigure the connections and settings of circuit cells located inside the LSI, may be used. This disclosure can be implemented as digital or analog processing. If future integrated circuit technology replaces LSIs as a result of advances in semiconductor technology or other derivative technologies, then functional blocks could be integrated using future integrated circuit technology. Biotechnology could also be applied.

[0276] This disclosure can be implemented by any type of device, apparatus, or system having communication capabilities, which is called a communication device.

[0277] Some non-limiting examples of such communication devices include telephones (e.g., cellular phones, smartphones), tablets, 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, telehealth / telemedicine (remote health and medicine) devices, and vehicles that provide communication functionality (e.g., automobiles, aircraft, ships) and various combinations thereof.

[0278] Communication devices are not limited to portable or mobile devices, and may include any type of non-portable or fixed device, device or system, such as smart home devices (e.g., appliances, lighting, smart meters, control panels), vending machines, and any other “thing” in an Internet of Things (IoT) network.

[0279] Communication may include, for example, the exchange of data through cellular systems, wireless LAN systems, satellite systems, and various combinations thereof.

[0280] A communication device may include devices such as controllers or sensors coupled to a communication device that performs the communication functions described in this disclosure. For example, a communication device may include controllers or sensors that generate control signals or data signals used by the communication device that performs the communication functions of the communication device.

[0281] Communication devices may also include infrastructure facilities such as base stations and access points, and other devices, devices, or systems that communicate with or control devices in the above-mentioned, non-limiting examples.

[0282] An example of an unrestricted station is one of a first group of stations interacting with a multilink station logical entity (i.e., an MLD), where several stations share a common medium access control (MAC) data services interface to a higher layer, and the common MAC data services interface is associated with a common MAC address or traffic identifier (TID).

[0283] Therefore, it can be seen that this embodiment provides a communication device and method for operation across multiple links, particularly for secure retransmission over multiple links, in order to fully realize the throughput gain of multilink communication.

[0284] While the preceding detailed description of this embodiment presents exemplary embodiments, a vast number of variations naturally exist. Furthermore, the exemplary embodiments are examples and are not intended to limit the scope, applicability, operation, or configuration of this disclosure. Rather, the preceding detailed description will provide a useful roadmap for implementing the exemplary embodiments, and various modifications may be made to the function and arrangement and operation methods of the steps described in the exemplary embodiments, and to the modules and structures of the devices described in the exemplary embodiments, without departing from the scope presented in the appended claims.

[0285] According to this disclosure, the following examples were provided, namely, 1. One of several communication devices that are in conjunction with a first multilink device (MLD), wherein the communication device is A receiver that, during operation, receives a first data frame containing an address resolution request from a requesting communication device, wherein the address resolution request contains the Internet Protocol (IP) address of a first MLD, and the receiver A circuit that, during operation, determines whether the requesting communication device is coordinating with a second MLD and generates a second data frame including an address resolution response, wherein the address resolution response includes, in response to the determination that the requesting communication device is not coordinating with the second MLD, the medium access control (MAC) address of the communication device, or in response to the determination that the requesting communication device is coordinating with the second MLD, the MLD MAC address of the first MLD, and A communication device equipped with the following features.

[0286] 2. A communication device according to Example 1, in which an address resolution request is one of an Address Resolution Protocol (ARP) request packet and a neighbor solicitation message, and an address resolution response is one of an ARP response packet and a neighbor advertisement message.

[0287] 3. A communication device according to Example 1, wherein the first data frame includes an indication of whether the requesting communication device is coordinating with the second MLD, and the determination is made based on the indication, and in response to the determination, the second data frame includes an indication of whether the communication device is coordinating with the first MLD.

[0288] 4. The indication is included in the protocol version subfield of the frame control field of the first data frame and the second data frame, respectively, in the communication device according to Example 3.

[0289] 5. The indication is included in the least significant bit of the MAC address relating to the requesting communication device, as in Example 3.

[0290] 6. The receiver further receives an MLD address query request frame including the MLD MAC address of the first MLD, and the circuit further generates an MLD address query response frame including the MAC address of each of the plurality of communication devices and the identifier of the operating link The communication device according to Example 1, further configured as such.

[0291] 7. The MLD address query request frame and the MLD address query response frame are preconfigured action frames or encapsulated within a preconfigured data frame. The communication device according to Example 6.

[0292] 8. The MLD address query request frame is received from another communication device that is or is not in cooperation with the MLD. The communication device according to Example 7.

[0293] 9. The circuit is further configured to set at least one least significant bit of (i) the source address field in an address resolution request with the MAC address related to the requesting communication device for including an indication, and (ii) the source address field in an address resolution response with the MLD MAC address of the first MLD for including an indication. The communication device according to Example 3.

[0294] 10. In response to the determination that the requesting communication device is in cooperation with the second MLD, the circuit sets the least significant bit of the MAC address of the tunnel direct link setup (TDLS) initiator communication device in the TDLS request frame transmitted to the TDLS responder communication device further configured as such, The TDLS initiator communication device is one of the communication device and the requesting communication device, the TDLS responder communication device is the remaining one of the communication device and the requesting communication device, and the least significant bit indicates the association of the TDLS initiator communication with the MLD. The communication device according to Example 1.

[0295] 11. The communication device is an access point (AP), and the first MLD is the AP MLD, as in Example 1.

[0296] 12. In response to the determination that the requesting communication device is not in conjunction with the second MLD and the destination address field of the first data frame contains either the broadcast address or the MLD MAC address of the MLD associated with the AP MLD, the circuit: The first data frame is forwarded only to one or more communication devices in the basic service set associated with the requesting communication device. A communication device of Example 11, further configured as follows.

[0297] 13. In response to the determination that the requesting communication device is associated with the second MLD and the destination field of the first data frame contains the MAC address of another communication device that is not associated with the MLD but is associated with one of several communication devices that are associated with the AP MLD, the circuit: The first data frame is forwarded only to one or more communication devices in the basic service set associated with the requesting communication device. A communication device of Example 11, further configured as follows.

[0298] 14. The communication device is a station, and the first MLD is a non-AP-MLD, as in Example 1.

[0299] 15. One of several access points (APs) that are working in conjunction with AP MLD, where the AP is: A receiver that, during operation, receives a first data frame from a requesting communication device, the address resolution request includes the IP address of a first MLD associated with an AP MLD, and the first MLD comprises a plurality of communication devices. A circuit that, during operation, determines whether a requesting communication device is coordinating with a second MLD associated with an AP MLD, and generates a second data frame including an address resolution response, wherein the address resolution response, in response to the determination that the requesting communication device is not coordinating with the second MLD, includes the MAC address of one of several communication devices coordinating with the first MLD, or in response to the determination that the requesting communication device is coordinating with the second MLD, includes the MLD MAC address of the first MLD, and An access point (AP) equipped with [a specific feature].

[0300] 16. An address resolution request is one of the ARP request packet and neighbor solicitation message, and an address resolution response is one of the ARP response packet and neighbor advertisement message, according to Example 15 of the AP.

[0301] 17. The receiver further receives an MLD address query request frame containing the MLD MAC address of the first MLD, and the circuit then... Generate an MLD address query response frame containing the MAC address and operating link identifier of each of the multiple communication devices interacting with the first MLD. AP configured as shown in Example 15.

[0302] 18. The receiver further receives an MLD address query request frame containing the MAC address of the associated communication device, and the circuit then... Generates an MLD address query response frame containing the MAC address of the related communication device and the identifier of the operating link. AP, further configured as shown in Example 15.

[0303] 19. In response to the determination that the requesting communication is not in conjunction with the second MLD and the destination address field of the first data frame contains either the broadcast address or the MLD MAC address of an MLD associated with the AP MLD, including the first MLD, the circuit: The requesting communication device forwards the first data frame only to one or more communication devices in the associated basic service set. AP, further configured as shown in Example 15.

[0304] 20. In response to the determination that the requesting communication device is associated with the second MLD and the destination field of the first data frame contains the MAC address of another communication device that is not associated with the MLD but is associated with one of the APs that is associated with the AP MLD, the circuit: The requesting communication device forwards the first data frame only to one or more communication devices in the associated basic service set. AP, further configured as shown in Example 15.

[0305] 21. The circuit is, To indicate that the communication device is associated with the first MLD, set the least significant bit of the source address field in the address resolution response containing the MLD MAC address of the first MLD. AP, further configured as shown in Example 15.

[0306] 22. Before transferring the first data frame, the circuit sets the least significant bit of the source address field, which contains the MAC address relating to the requesting communication device included in the address resolution request included in the first data frame. It is further configured in this way, The least significant bit indicates whether the requesting communication device is associated with the second MLD. AP by Example 19 or 30.

[0307] 23. A step of receiving a first data frame from a requesting communication device, wherein the address resolution request includes the IP address of the first MLD, A step of determining whether the requesting communication device is in cooperation with the second MLD, A step of generating a second data frame containing an address resolution response, wherein the address resolution response, in response to a determination that the requesting communication device is not in cooperation with the second MLD, contains the MAC address of one of the multiple communication devices in cooperation with the first MLD, or in response to a determination that the requesting communication device is in cooperation with the second MLD, contains the MLD MAC address of the first MLD. A communication method that includes the following features.

Claims

1. A requesting communication device that makes an Address Resolution Protocol (ARP) request to an Access Point Multilink Device (AP MLD) which includes multiple cooperative access points (APs), A transmission unit that sends an ARP request to the aforementioned AP MLD, which includes the target IP address, which is the Internet Protocol (IP) address to be resolved. If the target IP address corresponds to a non-access point multilink device (non-AP MLD), the receiving circuit receives an ARP response that includes the MLD medium access control (MLD MAC) address of the non-AP MLD as the source MAC address, and receives a frame that includes the MLD MAC address of the requesting communication device as the receiving address directly from the non-AP MLD via the link. A requesting communication device equipped with the following features.

2. If the target IP address corresponds to a station (STA), the receiving circuit receives the ARP response which includes the MAC address of the STA as the source MAC address. The requesting communication device according to claim 1.

3. The requesting communication device is a different non-AP MLD from the non-AP MLD corresponding to the target IP address. The requesting communication device according to claim 1.

4. The receiving circuit maintains a mapping between the MLD MAC address and IP address for each non-AP MLD, and updates the mapping between the MLD MAC address and IP address if the IP address of the non-AP MLD changes. The requesting communication device according to claim 1.

5. The ARP response is one given by the AP MLD that received the ARP request, instead of the non-AP MLD. The requesting communication device according to claim 1.

6. The least significant bit of the first octet among the six octets included in the MAC address of the requesting communication device is used as an MLD indicator to show whether or not the MAC address of the requesting communication device is an MLD MAC address. The requesting communication device according to claim 1.

7. The MLD indication is set to 1 if the MAC address of the requesting communication device is the MLD MAC address, and to 0 if it is the MAC address of STA. The requesting communication device according to claim 6.

8. The aforementioned ARP request is for finding a device having the aforementioned target IP address. The requesting communication device according to claim 7.

9. A communication method for a requesting communication device that makes an Address Resolution Protocol (ARP) request to an Access Point Multilink Device (AP MLD) including multiple cooperative access points (APs), An ARP request is sent to the aforementioned AP MLD, including the target IP address, which is the Internet Protocol (IP) address to be resolved. If the target IP address corresponds to a non-access point multilink device (non-AP MLD), an ARP response is received that includes the MLD media access control (MLD MAC) address of the non-AP MLD as the source MAC address, and a frame including the MLD MAC address of the requesting communication device as the receiving address is received directly from the non-AP MLD via the link. Communication method.

10. If the target IP address corresponds to a station (STA), the ARP response received includes the MAC address of the STA as the source MAC address. The communication method according to claim 9.

11. The requesting communication device is a different non-AP MLD from the non-AP MLD corresponding to the target IP address. The communication method according to claim 9.

12. For each non-AP MLD, maintain the mapping between the MLD MAC address and its IP address, and update the mapping between the MLD MAC address and its IP address if the IP address of the non-AP MLD changes. The communication method according to claim 9.

13. The ARP response is one given by the AP MLD that received the ARP request, instead of the non-AP MLD. The communication method according to claim 9.

14. The least significant bit of the first octet among the six octets included in the MAC address of the requesting communication device is used as an MLD indicator to show whether or not the MAC address of the requesting communication device is an MLD MAC address. The communication method according to claim 9.

15. The MLD indication is set to 1 if the MAC address of the requesting communication device is the MLD MAC address, and to 0 if it is the MAC address of STA. The communication method according to claim 15.

16. The aforementioned ARP request is for finding a device having the aforementioned target IP address. The communication method according to claim 15.

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