A message transmission method and system

Abstract

The application discloses a message transmission method and system. The system comprises a core network EPC and at least one terminal device. After receiving a first address resolution request sent by an uplink device, the core network EPC broadcasts an air interface paging message to the at least one terminal device. The terminal device assembles an address resolution request of an Ethernet structure based on a destination IP to obtain a second address resolution request, and sends the second address resolution request to corresponding respective downlink devices. When the terminal device receives a first address resolution reply sent by the downlink device, the terminal device sends a NAS message to the core network EPC. After receiving the NAS message, the core network EPC sends a second address resolution reply to the uplink device. The second address resolution reply comprises a destination IP and a MAC address of a PGW of the core network EPC. The second address resolution reply indicates that the destination IP has been found, and a proxy address is the MAC address of the PGW. In the application, the search for a device accessed by the uplink device to the destination IP is realized, and the transmission of a two-layer Ethernet message of the uplink device and the downlink device is realized.

Description

Technical Field

[0001] This application relates to the field of digital communication technology, and in particular to a message transmission method and system. Background Technology

[0002] In traditional 4G / 5G wireless networks, the IP data transmitted between the UE (User Equipment) and the core network EPC (Evolved Packet Core) does not contain an Ethernet header. Such networks can only transmit Layer 3 IP packets and cannot transmit Layer 2 Ethernet data. Most current industrial internet systems have adopted Wi-Fi technology, which supports Layer 2 Ethernet data; therefore, most current industrial internet systems use Layer 2 transmission.

[0003] Currently, to upgrade existing networks to 4G wireless networks, a VPN model is typically used during network replanning to achieve mutual backup between the 4G network and WiFi. This involves establishing a Layer 2 VPN at the core network front-end and the UE back-end to ensure normal Ethernet data transmission. However, using the VPN model not only adds extra equipment, increasing the cost and difficulty of the upgrade, but also significantly increases the load by requiring notifications to all UEs for a large number of broadcast messages. Summary of the Invention

[0004] This application provides a message transmission method and system, as follows:

[0005] A message transmission method applied to the core network EPC, the method includes:

[0006] Receive a first address resolution request sent by the uplink device, the first address resolution request including the destination IP;

[0007] The destination IP is encapsulated in an air interface paging message and broadcast through a base station, so that after receiving the air interface paging message, the terminal device obtains the destination IP and generates a second address resolution request, which is then sent to the downstream device of the terminal device.

[0008] Receive a NAS message sent by the terminal device over the air interface. The NAS message includes the destination IP and the device identifier of the terminal device, which is used to indicate that the destination IP belongs to a downstream device of the terminal device.

[0009] A second address resolution response is sent to the uplink device. The second address resolution response includes the destination IP and the MAC address of the PGW of the core network EPC, so that the uplink device sends a unicast message with the MAC address of the PGW as the destination MAC address.

[0010] Optionally, after receiving the NAS message sent by the terminal device, the method further includes:

[0011] Generate and record query results, which include the correspondence between the destination IP and the device identifier of the terminal device.

[0012] Optionally, this method also includes:

[0013] Receive a unicast message encapsulated with the destination IP address, sent by the uplink device with the MAC address of the PGW as the destination MAC address;

[0014] Obtain the device identifier of the terminal device based on the destination IP;

[0015] The unicast message is sent to the terminal device, so that the terminal device forwards the unicast message to the downstream device corresponding to the destination IP based on the destination IP.

[0016] A message transmission method, applied to a terminal device, includes:

[0017] Receive air interface paging messages broadcast by the core network EPC through the base station, wherein the air interface paging messages are encapsulated by the core network EPC based on the destination IP sent by the uplink device;

[0018] Based on the address resolution request of the Ethernet structure assembled from the destination IP, a second address resolution request is obtained, and the second address resolution request is sent to each downstream device of the terminal device;

[0019] In response to receiving a first address resolution reply from the downstream device corresponding to the destination IP, a NAS message is sent to the core network EPC via the air interface, so that the core network EPC records the correspondence between the destination IP and the device identifier of the terminal device, and a second address resolution reply is sent to the uplink device. The first address resolution reply includes the destination IP and the MAC address of the downstream device corresponding to the destination IP, and the second address resolution reply includes the destination IP and the MAC address of the PGW of the core network EPC. The NAS message includes the destination IP and the device identifier of the terminal device, and is used to indicate that the destination IP belongs to the downstream device of the terminal device.

[0020] Optionally, this method also includes:

[0021] Receive a unicast message encapsulated with the destination IP address sent by the core network EPC;

[0022] Based on the destination IP, the unicast message is forwarded to the downstream device corresponding to the destination IP.

[0023] A message transmission method, applied to a terminal device, includes:

[0024] Receive a first address resolution request sent by the downstream device, wherein the first address resolution request includes the destination IP;

[0025] The destination IP is encapsulated in a first NAS message and sent to the core network EPC via a base station. After receiving the first NAS message, the core network EPC obtains the destination IP and generates a second address resolution request. The second address resolution request is broadcast to each uplink device of the core network EPC, and a first address resolution reply is received. The first address resolution reply includes the MAC address of the uplink device corresponding to the destination IP.

[0026] Receive a second NAS message sent by the core network EPC over the air interface. The second NAS message includes the destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP.

[0027] Based on the second NAS message, a second address resolution response is generated and sent to the downstream device, so that the downstream device sends a unicast message to the uplink device corresponding to the destination IP. The second address resolution response includes the MAC address of the uplink device corresponding to the destination IP.

[0028] A message transmission method applied to the core network EPC, the method includes:

[0029] Receive the first NAS message encapsulated with the destination IP sent by the terminal device through the base station;

[0030] Obtain the destination IP and generate a second address resolution request, then broadcast the second address resolution request to each uplink device of the core network EPC;

[0031] Receive a first address resolution response, wherein the first address resolution response includes the MAC address of the uplink device corresponding to the destination IP;

[0032] The terminal device sends a second NAS message over the air interface. The second NAS message includes the destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP. This enables the terminal device to generate and send a second address resolution response to the downstream device based on the second NAS message. The downstream device then sends a unicast message to the uplink device corresponding to the destination IP. The second address resolution response includes the MAC address of the uplink device corresponding to the destination IP.

[0033] A message transmission system includes a core network EPC and at least one terminal device;

[0034] The core network EPC is used to encapsulate the first destination IP in the address resolution request sent by the uplink device in an air interface paging message, and broadcast the air interface paging message to at least one of the terminal devices through the base station;

[0035] The terminal device is used to send a resolution request encapsulated with the first destination IP to each of the downstream devices of the terminal device, and in response to receiving the first address resolution reply sent by the downstream device, sends a NAS message to the core network EPC. The first address resolution reply includes the first destination IP and the MAC address of the downstream device, and the NAS message includes the first destination IP and the device identifier of the terminal device.

[0036] After receiving the NAS message, the core network EPC sends a second address resolution response to the uplink device. The second address resolution response includes the first destination IP and the MAC address of the PGW of the core network EPC, so that the uplink device sends a unicast message with the MAC address of the PGW as the destination MAC address.

[0037] Optionally, the core network EPC is further configured to: receive a unicast message encapsulated with the first destination IP sent by the uplink device using the MAC address of the PGW as the proxy address, obtain the device identifier of the terminal device based on the first destination IP, and send the unicast message to the terminal device;

[0038] The terminal device is further configured to: after receiving the unicast message, forward the unicast message to the downstream device based on the first destination IP.

[0039] Optionally, the terminal device is further configured to: receive an address resolution request including a second destination IP sent by any of the downstream devices; encapsulate the second destination IP in a first NAS message; and send the first NAS message to the core network EPC via the base station;

[0040] The core network EPC is also used to broadcast the address resolution request encapsulated with the second destination IP to each uplink device of the core network EPC, and after receiving the MAC address of the uplink device corresponding to the destination IP sent by the uplink device, send a second NAS message to the terminal device. The second NAS message includes the second destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP.

[0041] The terminal device is further configured to generate and send an address resolution reply encapsulated with the MAC address of the uplink device corresponding to the second destination IP to the downstream device after receiving the second NAS message, so that the downstream device can send a unicast message to the uplink device corresponding to the destination IP.

[0042] Optionally, the system further includes: the uplink device and / or the downstream device, wherein the uplink device is connected to the core network EPC via an Ethernet network, and the downstream device is connected to the terminal device via a local area network;

[0043] The uplink device is used to receive the second address resolution reply and then send a unicast message encapsulated with the destination IP address using the MAC address of the PGW as the proxy address.

[0044] After receiving the second address resolution request, the downstream device, upon confirming that the destination IP is the device IP of the downstream device, generates and sends the first address resolution response to the terminal device.

[0045] As can be seen from the above technical solutions, the message transmission method and system provided in this application include a core network EPC and at least one terminal device. The method includes the core network EPC receiving a first address resolution request from an uplink device (i.e., a network-side device), broadcasting an air interface paging message to at least one terminal device. The terminal device assembles an Ethernet structure address resolution request based on the destination IP, obtains a second address resolution request, and sends the second address resolution request to the corresponding downstream device. When the terminal device receives a first address resolution reply from the downstream device, it sends a NAS message to the core network EPC. After receiving the NAS message, the core network EPC sends a second address resolution reply to the uplink device. The first address resolution reply includes the destination IP and the MAC address of the downstream device; that is, the first address resolution reply indicates that the destination IP has been found and the MAC address is the MAC address of the downstream device recorded in the first address resolution reply. The NAS message sent by the terminal device to the core network EPC includes the destination IP and the device identifier of the terminal device; that is, the NAS message is used to indicate that the destination IP belongs to a downstream device of the terminal device. The second address resolution response includes the destination IP and the MAC address of the PGW of the core network EPC. That is, the second address resolution response indicates that the destination IP has been found and the proxy address is the MAC address of the PGW. Therefore, through the core network EPC and terminal equipment in this application, the device for finding the destination IP of the uplink device is realized, enabling the uplink device to send unicast messages using the PGW's MAC address as the proxy address, thereby achieving the transmission of Layer 2 Ethernet messages between the uplink device and the downstream devices. Attached Figure Description

[0046] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0047] Figure 1 This application provides a schematic diagram of the structure of a message transmission system according to an embodiment of the present application.

[0048] Figure 2 A flowchart illustrating a specific implementation of a message transmission system provided in this application embodiment;

[0049] Figure 3 This application provides a schematic diagram of a network architecture.

[0050] Figure 4 A signaling diagram of an IP lookup process provided in an embodiment of this application;

[0051] Figure 5 A signaling diagram of an access flow provided in an embodiment of this application;

[0052] Figure 6 Signaling diagram of another IP lookup process provided in an embodiment of this application. Detailed Implementation

[0053] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0054] The message transmission method provided in this application embodiment is applied to, but not limited to, forwarding Layer 2 network data in a 4 / 5G metropolitan area network architecture, that is, transparently transmitting Layer 2 Ethernet messages in a 4 / 5G wireless network. Figure 1 A message transmission system is illustrated, comprising a core network EPC, network-side devices, terminal devices, and their downstream devices. The number of terminal devices and their downstream devices is unlimited. Downstream devices refer to devices connected to the terminal devices via interfaces, and network-side devices refer to the uplink devices of the core network EPC. The uplink devices are connected to the core network EPC via Ethernet communication, and the downstream devices are connected to the terminal devices via a local area network (LAN), such as a LAN formed by wired or Wi-Fi connections.

[0055] It should be noted that the message transmission method provided in this application is applied to realize the transmission of Layer 2 Ethernet messages between network-side devices and downstream devices.

[0056] It should be noted that the message transmission method provided in this application has good applications in industrial internet and small-scale private networks. One possible application scenario is as follows: In practical applications, a wireless Wi-Fi network already exists as an industrial internet network. However, due to the instability of Wi-Fi and the lack of QoS guarantee, a 4G or 5G network needs to be added as a backup to the Wi-Fi. Since Wi-Fi technology is a local area network technology, if 4G / 5G devices are installed in this network, all IoT devices in the entire network will need to be rebuilt. Obviously, the cost of converting a Layer 2 network into a Layer 3 network is very high, and after the conversion, a large number of broadcast messages need to be sent to all terminal devices, resulting in extremely high load. In view of this, the message transmission method provided in this application can realize Layer 2 data (i.e., Layer 2 Ethernet message) transmission without modifying the existing device network.

[0057] Figure 2 The specific implementation flow of a message transmission method provided in the embodiments of this application is as follows: Figure 1 As shown, this method specifically includes:

[0058] S201. The network-side device sends the first address resolution request to the core network EPC.

[0059] In this embodiment, the network-side device refers to the service initiator, and the first address resolution request includes the destination IP, which refers to the IP address of the device to be searched (i.e., the service executor). Specifically, the first address resolution request is used to instruct the device whose IP address is the destination IP.

[0060] S202. After receiving the first address resolution request, the core network EPC encapsulates the destination IP in an air interface paging message and broadcasts the air interface paging message to at least one terminal device through the base station.

[0061] An optional method for the core network EPC to broadcast air interface paging messages via a base station includes: after receiving the first address resolution request, the PGW (PDN Gateway) in the core network EPC forwards the first address resolution request to the MME (Mobility Management Entity). The MME encapsulates the destination IP included in the first address resolution request in an air interface paging message and broadcasts the air interface paging message to the base station. The base station then broadcasts the air interface paging message to each terminal device.

[0062] S203. After receiving the air interface paging message, the terminal device assembles an Ethernet-structured address resolution request based on the destination IP encapsulated in the air interface paging message to obtain a second address resolution request, and sends the second address resolution request to the downstream device of the terminal device.

[0063] S204. After receiving the second address resolution request, the downstream device confirms whether the device IP is the destination IP. If so, it generates and sends the first address resolution reply to the terminal device.

[0064] In this embodiment, the first address resolution response includes the destination IP and the MAC address of the downstream device. The first address resolution response is used to indicate that the destination IP belongs to the downstream device.

[0065] S205. Upon receiving the first address resolution reply, the terminal device sends a NAS message to the core network EPC.

[0066] In this embodiment, the terminal device sends a NAS (Non-Access-stratum) message to the MME. The NAS message includes the destination IP and the device identifier of the terminal device, denoted as the device ID (identification), which indicates that the destination IP has been found and that the destination IP belongs to a downstream device of the terminal device.

[0067] S206. After receiving the NAS message, the core network EPC generates and records the query results.

[0068] In this embodiment, the query results include the correspondence between the destination IP and the device ID of the terminal device. The terminal device corresponding to the destination IP refers to the terminal device connected to the downstream device to which the destination IP belongs.

[0069] In this embodiment, after receiving the NAS message, the MME generates and records the query results, that is, the MME records which terminal device the target IP's downstream device is connected to.

[0070] S207. The core network EPC sends a second address resolution response to the network-side device.

[0071] In this embodiment, the second address resolution response includes the destination IP address and the MAC address of the PGW of the core network EPC. The second address resolution response is used to indicate that the destination IP address has been found and that the proxy address is the MAC address of the PGW of the core network EPC.

[0072] S208. After receiving the second address resolution reply, the network-side device sends a unicast message to the core network EPC.

[0073] In this embodiment, after receiving the second address resolution reply, the network-side device resolves the proxy address and sends a unicast message with the proxy address as the target address. Since the target address is the MAC address of the PGW of the core network EPC, the core network EPC can receive the unicast message.

[0074] S209. After receiving a unicast message, the core network EPC obtains the device ID of the terminal device corresponding to the destination IP based on the query result, and sends the assembled message to the terminal device corresponding to the destination IP, i.e., the target terminal.

[0075] It should be noted that the core network EPC sends the assembled message to the target terminal by sending the assembled message to the base station corresponding to the target terminal. The base station then sends the assembled message to the target terminal. Specifically, the IP packets of PC1 and PC3 (the first packet) are treated as data and encapsulated in the IP packets between PC1 and UE1. The IP communication between PC1 and UE1 is a traditional 4G Layer 3 communication network. After UE1 receives the IP packet, it removes the IP header. The data part at this time is exactly the IP packet of PC1 and PC3 (including the IP header and IP data part).

[0076] S210. After receiving the assembly message, the target terminal forwards the assembly message to the downstream device to which the destination IP belongs, based on the MAC address of the downstream device.

[0077] As can be seen from the above technical solutions, the message transmission method and system provided in this application involves the core network EPC receiving a first address resolution request sent by an uplink device (i.e., a network-side device). The core network EPC then broadcasts an air interface paging message to at least one terminal device via a base station. The terminal device assembles an Ethernet structure address resolution request based on the destination IP to obtain a second address resolution request, and sends the second address resolution request to the corresponding downstream device. At this time, the terminal device can broadcast the second address resolution request to each of its downstream devices. If the terminal device identifies that the destination IP belongs to its downstream device, it can also directly send the second address resolution request to the downstream device corresponding to the destination IP, or use other sending methods. When the terminal device receives the first address resolution reply sent by the downstream device, it sends a NAS message to the core network EPC. After receiving the NAS message, the core network EPC sends a second address resolution reply to the uplink device. The first address resolution reply includes the destination IP and the MAC address of the downstream device; that is, the first address resolution reply indicates that the destination IP has been found and the MAC address is the MAC address of the downstream device recorded in the first address resolution reply. The NAS message sent by the terminal device to the core network EPC includes the destination IP and the terminal device's device ID. In other words, the NAS message indicates that the destination IP belongs to a downstream device of the terminal device. The second address resolution response includes the destination IP and the MAC address of the core network EPC's PGW. That is, the second address resolution response indicates that the destination IP has been found and the proxy address is the PGW's MAC address.

[0078] As can be seen, by using the core network EPC and terminal equipment, the device that is the destination IP of the uplink device can be found, so that the uplink device can send unicast messages using the MAC address of the PGW as the proxy address.

[0079] Furthermore, after the core network EPC receives the unicast message containing the destination IP encapsulated by the uplink device, which uses the MAC address of the PGW as the proxy address, it obtains the device ID of the terminal device based on the destination IP, thus determining which specific terminal device the downstream device is under; and sends the unicast message to the terminal device. After receiving the unicast message containing the destination IP, the terminal device forwards the unicast message to the downstream device based on the first address resolution reply and the destination IP.

[0080] It is evident that the message transmission system built through the core network EPC and terminal equipment enables Layer 2 Ethernet message transmission between uplink devices and downstream devices.

[0081] Figure 3A specific network architecture is shown, which includes network-side device PC1 (IP address 192.168.1.1), core network EPC (including PGW and MME, where the MME's IP address is 10.10.10.10), base station eNodeB, terminal device UE1 (IP address 10.10.10.20) and its downstream devices PC2 (IP address 192.168.1.2) and PC3 (IP address 192.168.1.3), as well as terminal device UE2 and its downstream device PC6 (IP address 192.168.1.6).

[0082] Among them, PC1 is an IP device connected to the EPC, while PC2, PC3, and PC6 are IP devices connected to the UE on the wireless side. The entire "EPC-eNodeB-UE" is a 4G network element. PC1, PC2, PC3, and PC6 are wired access devices or devices that connect to 4GCPE (a special type of UE that uses 4G for uplink and WiFi for downlink coverage, and is in a bridging relationship) via WiFi (collectively referred to as the UE's connected devices).

[0083] In a wireless network, the network-side device PC1 and the downstream devices (PC2, PC3, and PC6) of each terminal device belong to the same network segment and can transmit Layer 2 Ethernet packets. However, after upgrading to 4G or 5G networks, the network-side device and the downstream devices of each terminal device cannot directly transmit Layer 2 Ethernet packets. Taking PC1 initiating access to PC3 as an example, a packet transmission method provided in this application embodiment is specifically described as follows:

[0084] Figure 4 The destination IP lookup process is shown, and it includes the following steps:

[0085] A1 and PC1 send an address resolution request to EPC.

[0086] In this embodiment, the address resolution request includes the destination IP, such as... Figure 4 As shown, the destination IP is 192.168.1.3. The Address Resolution Protocol (ARP) request is used to indicate the destination IP, that is, "Who is 192.168.1.3".

[0087] A2 and EPC encapsulate the destination IP in an air interface paging message and broadcast the air interface paging message to the eNodeB, so that the eNodeB can broadcast the air interface paging message to UE1 and UE2.

[0088] Specifically, EPC includes PGW (PDN Gateway) and MME (Mobility Management Entity). After receiving an ARP request, PGW sends the ARP request to MME. MME encapsulates the destination IP indicated by the ARP request in an air interface paging message and broadcasts the Paging message to eNodeB. The Paging message is used to indicate the MAC address where the destination IP is located, i.e., "Where is 192.168.1.3".

[0089] A3. After receiving Paging, the UE sends the address resolution request of the assembled Ethernet structure to the corresponding downstream device.

[0090] In this embodiment, the UE includes UE1 and UE2, such as Figure 4 As shown, UE1 sends the address resolution request (ARP request) of the assembled Ethernet structure to its downstream devices PC2 and PC3, and UE2 sends the address resolution request (ARP request) of the assembled Ethernet structure to its downstream device PC6.

[0091] A4. After receiving the ARP request, if the device IP is the destination IP, the connected device will send an address resolution reply to the UE.

[0092] like Figure 4 As shown, PC3's device IP is the destination IP, meaning PC3 is the device PC1 is trying to access. Therefore, PC3 sends an address resolution reply (Arp response) to UE1. The Arp response includes PC3's MAC address, which is used to notify UE1 that the MAC address of the destination IP is PC3's MAC address.

[0093] It should be noted that after receiving an ARP request, if the device's IP address is not the destination IP address, it will not respond, or it will issue a query failure command, such as... Figure 4 As shown, if the device IPs of PC2 and PC6 are not the destination IPs, no response will be given.

[0094] After receiving the Arp response, A5 and UE1 send NAS to the eNodeB, so that the eNodeB can send a NAS message to the EPC.

[0095] In this embodiment, the MME determines that the device where the destination IP is located (i.e. the device to be found) is the downstream device of UE1 by using the UE identification code (also known as UE identifier, device identifier, or device ID) in the NAS message.

[0096] A6. After receiving the NAS message, EPC records the query results, uses the MAC address of PGW as the proxy address of the destination IP, generates an ARP response, and sends it to PC1.

[0097] In this embodiment, the query result includes the correspondence between the destination IP and UE1, that is, the MME record of the EPC records the device ID of the terminal device connected to the downstream device to which the destination IP belongs. The Arp response is used to indicate that the MAC address of the PGW is the proxy address of the destination IP, that is, the proxy MAC address of the device where the destination IP is located is the MAC address of the PGW.

[0098] Depend on Figure 4 As shown in the process, a proxy technology is used for ARP requests. When the network-side PGW uplink device receives an ARP request from the UE indicating that the target IP has been found, the UE uses the PGW's MAC address as the proxy address to send back the ARP request, regardless of whether it is in the same network segment as the PGW. This enables the lookup of the target IP.

[0099] Figure 5 This illustrates the access process where a network-side device initiates a unicast message access, specifically including:

[0100] B1 and PC1 send unicast messages to the proxy address of the destination IP.

[0101] In this embodiment, PC1 obtains the MAC address of the PGW as the proxy address of the destination IP through NAS message parsing, and sends a unicast message encapsulating the destination IP and the PGW's MAC address to the PGW's MAC address, such as... Figure 5 As shown, PC1 sends the "Unicast IP + MAC address packet" to EPC.

[0102] B2. EPC obtains the MAC address of UE1 from the query results based on the destination IP and sends a unicast message to UE1.

[0103] In this embodiment, the EPC, based on the MAC address of UE1, sends a unicast packet encapsulated with the destination IP address to the base station where UE1 is located via unicast GTPU (GPRS Tunneling Protocol User Plane). The base station then transmits the unicast packet encapsulated with the destination IP address (e.g., ...) to the base station. Figure 5 The IP packet (Dst:192.168.1.3) shown is sent to UE1.

[0104] After receiving the unicast message, B3 and UE1 send the unicast message to the downstream device based on the MAC address of the downstream device.

[0105] like Figure 5 As shown, the unicast message sent from UE1 to PC3 specifically includes: Src MAC address: UE1 MAC address, Dst MAC address: PC2 MAC address, SRC IP: PC1 IP, and Dst IP: PC3 IP. It should be noted that an Ethernet packet contains a four-tuple: source MAC address, destination MAC address, source IP, and destination IP.

[0106] As can be seen from the above technical solution, when the network-side device initiates a unicast packet to access the destination IP, since the destination MAC address is the MAC address of the PGW, the core network EPC can successfully receive the unicast packet and, based on the destination IP, learn the address from the address learning phase (i.e., Figure 4 The destination IP lookup process (as shown) retrieves the query results and finds the terminal device UE1 corresponding to the destination IP, thus determining which UE is connected to the device with the destination IP. The assembled packet is then sent to UE1. Upon receiving the assembled packet, UE1 checks if the destination IP is not its own IP address and forwards the assembled packet to the connected device, achieving wired-side forwarding of the assembled packet. This enables the transmission of Layer 2 Ethernet packets.

[0107] Through the above embodiments, it can be seen that the message transmission system provided in this application includes a core network EPC and network-side devices. The core network EPC encapsulates the first destination IP (i.e., the destination IP mentioned in the above embodiments) in the address resolution request sent by the uplink device in an air interface paging message, and broadcasts the air interface paging message to at least one terminal device through a base station. The terminal device sends the resolution request encapsulated with the first destination IP to each of its downstream devices. In response to receiving a first address resolution reply from a downstream device, the terminal device sends a NAS message to the core network EPC. The first address resolution reply includes the first destination IP and the MAC address of the downstream device. The NAS message includes the first destination IP and the device identifier of the terminal device. After receiving the NAS message, the core network EPC sends a second address resolution reply to the uplink device. The second address resolution reply includes the first destination IP and the MAC address of the core network EPC's PGW, so that the uplink device sends unicast messages with the PGW's MAC address as the destination MAC address. This achieves the purpose of the network-side device finding downstream devices based on IP and sending data to the downstream devices.

[0108] Furthermore, this system can also enable downstream devices (devices on the terminal side) to locate network-side devices based on IP addresses and send data to those devices. Specific methods include:

[0109] C1. The terminal device receives an address resolution request including the second destination IP from any downstream device, encapsulates the second destination IP in the first NAS message, and sends the first NAS message to the core network EPC through the base station.

[0110] C2. The core network EPC will broadcast the address resolution request encapsulated with the second destination IP to each uplink device of the core network EPC. After receiving the MAC address of the uplink device corresponding to the destination IP from the uplink device, the second NAS message will be sent to the terminal device. The second NAS message includes the second destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP.

[0111] C3. After receiving the second NAS message, the terminal device generates and sends an address resolution reply containing the MAC address of the uplink device corresponding to the second destination IP to the downstream device, so that the downstream device can send a unicast message to the uplink device corresponding to the destination IP.

[0112] Taking PC3 searching for PC1 as an example, Figure 6 Example of a specific implementation flow for a message transmission method, such as Figure 6 As shown, the method includes:

[0113] D1 and PC3 send an address resolution request (Arp request) encapsulated with a second destination IP (i.e., 192.168.1.1) to the corresponding terminal device UE1.

[0114] The address resolution request is used to query the MAC address of the second destination IP, i.e., "Who is 192.168.1.1".

[0115] D2 and UE1 send a first NAS message encapsulating the second destination IP to the core network EPC via the base station to query whether the MAC address of the device corresponding to the second destination IP is an uplink device of the core network EPC, i.e., "is 192.168.1.1atEPC?".

[0116] D3. After receiving the first NAS message, the core network EPC will broadcast the address resolution request encapsulated with the second destination IP to each uplink device of the core network EPC.

[0117] D4. When PC1 receives an address resolution request encapsulated with a second destination IP and determines that the second destination IP is its own device IP, it sends an address resolution reply including its own MAC address to the core network EPC, that is, it sends an ARP response including "192.168.1.1 is at PC1" to the core network EPC.

[0118] D5. The core network EPC sends the second NAS message to the terminal device through the base station.

[0119] The second NAS message includes the second destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP. That is, the core network EPC informs the terminal device through the base station that the device corresponding to the second destination IP is the uplink device of the core network EPC, and informs the terminal device of the MAC address of the uplink device.

[0120] After receiving the second NAS message, D6 and UE1 generate and send an address resolution reply encapsulated with the MAC address of PC1 to the downstream device PC3 that initiated the query, so as to inform PC3 of the MAC address of the device corresponding to the second destination IP, so that PC3 can send data based on the MAC address.

[0121] It should be noted that the method for PC3 to send data based on this MAC address can be found by referring to [reference needed]. Figure 5 The process shown, that is, the method by which PC3 sends data based on this MAC address, includes:

[0122] D7 and PC3 send unicast messages to UE1.

[0123] D8 and UE1 obtain the MAC address of the GWP of EPC based on the destination IP, and send IP packets to EPC through the base station.

[0124] The IP packet is: "IP packet: DstIP:192.168.1.1; Src IP:192.168.1.3".

[0125] After receiving the IP packet, D9 and EPC send a unicast 802.3 packet to PC1 based on the MAC address of the uplink device.

[0126] like Figure 5 As shown, the unicast message sent by EPC specifically includes: Src MAC address: PGW MAC address, Dst MAC address: PC1 MAC address, SRC IP: PC3 IP, and Dst IP: PC1 IP.

[0127] As can be seen from the above, this system executes... Figure 6 The process shown enables the downstream device of the terminal device (UE) to actively initiate services, that is, the downstream device actively initiates a request for a MAC address and obtains the MAC address of the target IP, thereby realizing the initiation of services and the transmission of data.

[0128] It should be noted that, Figure 6This is only one optional method for downstream devices to find the MAC address of a device. This system can also implement other search processes. For example, after receiving the second destination IP, the terminal device can also broadcast the second destination IP to other downstream devices of the terminal device to find out whether the second destination IP is the device IP of other downstream devices of the terminal device.

[0129] As can be seen from the above, the message transmission system and method provided in this application embodiment solve the problem of low-cost forwarding of Layer 2 network data under 4 / 5G metropolitan area network architecture, and can be well applied in industrial internet and small-scale private networks. Specific implementation:

[0130] 1. By employing ARP proxy and spoofing techniques, combined with newly added NAS messages and paging messages, the ARP learning problem in Layer 2 forwarding is solved.

[0131] 2. To resolve the communication issues of the UE's downstream devices, access can be initiated proactively by the network side.

[0132] 3. Communication between devices can be achieved without changing the private network topology, effectively replacing WiFi or performing dual WiFi backup in the industrial Internet.

[0133] 4. Compared to existing technologies where Layer 2 forwarding requires a VPN tunnel and necessitates the addition of tunneling equipment on both sides of the 4G system, this application achieves Layer 2 Ethernet packet pass-through without requiring additional network equipment.

[0134] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0135] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0136] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A message transmission method, characterized in that, Applied to core network EPC, the method includes: Receive a first address resolution request sent by the uplink device, the first address resolution request including the destination IP; The destination IP is encapsulated in an air interface paging message and broadcast through a base station, so that after receiving the air interface paging message, the terminal device obtains the destination IP and generates a second address resolution request, which is then sent to the downstream device of the terminal device. Receive a NAS message sent by the terminal device over the air interface. The NAS message includes the destination IP and the device identifier of the terminal device, which is used to indicate that the destination IP belongs to a downstream device of the terminal device. A second address resolution response is sent to the uplink device. The second address resolution response includes the destination IP and the MAC address of the PGW of the core network EPC, so that the uplink device sends a unicast message with the MAC address of the PGW as the destination MAC address.

2. The method according to claim 1, characterized in that, After receiving the NAS message sent by the terminal device, the method further includes: Generate and record query results, which include the correspondence between the destination IP and the device identifier of the terminal device.

3. The method according to claim 1 or 2, characterized in that, The method further includes: Receive a unicast message encapsulated with the destination IP address, sent by the uplink device with the MAC address of the PGW as the destination MAC address; Obtain the device identifier of the terminal device based on the destination IP; The unicast message is sent to the terminal device, so that the terminal device forwards the unicast message to the downstream device corresponding to the destination IP based on the destination IP.

4. A message transmission method, characterized in that, Applied to a terminal device, the method includes: Receive air interface paging messages broadcast by the core network EPC through the base station, wherein the air interface paging messages are encapsulated by the core network EPC based on the destination IP sent by the uplink device; Based on the address resolution request of the Ethernet structure assembled from the destination IP, a second address resolution request is obtained, and the second address resolution request is sent to each downstream device of the terminal device; In response to receiving a first address resolution reply from the downstream device corresponding to the destination IP, a NAS message is sent to the core network EPC via the air interface, so that the core network EPC records the correspondence between the destination IP and the device identifier of the terminal device, and a second address resolution reply is sent to the uplink device. The first address resolution reply includes the destination IP and the MAC address of the downstream device corresponding to the destination IP, and the second address resolution reply includes the destination IP and the MAC address of the PGW of the core network EPC. The NAS message includes the destination IP and the device identifier of the terminal device, and is used to indicate that the destination IP belongs to the downstream device of the terminal device.

5. The method according to claim 4, characterized in that, The method further includes: Receive a unicast message encapsulated with the destination IP address sent by the core network EPC; Based on the destination IP, the unicast message is forwarded to the downstream device corresponding to the destination IP.

6. A message transmission method, characterized in that, Applied to a terminal device, the method includes: Receive a first address resolution request sent by the downstream device, wherein the first address resolution request includes the destination IP; The destination IP is encapsulated in a first NAS message and sent to the core network EPC via a base station. After receiving the first NAS message, the core network EPC obtains the destination IP and generates a second address resolution request. The second address resolution request is broadcast to each uplink device of the core network EPC, and a first address resolution reply is received. The first address resolution reply includes the MAC address of the uplink device corresponding to the destination IP. Receive a second NAS message sent by the core network EPC over the air interface. The second NAS message includes the destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP. Based on the second NAS message, a second address resolution response is generated and sent to the downstream device, so that the downstream device sends a unicast message to the uplink device corresponding to the destination IP. The second address resolution response includes the MAC address of the uplink device corresponding to the destination IP.

7. A message transmission method, characterized in that, Applied to core network EPC, the method includes: Receive the first NAS message encapsulated with the destination IP sent by the terminal device through the base station; Obtain the destination IP and generate a second address resolution request, then broadcast the second address resolution request to each uplink device of the core network EPC; Receive a first address resolution response, wherein the first address resolution response includes the MAC address of the uplink device corresponding to the destination IP; The terminal device sends a second NAS message over the air interface. The second NAS message includes the destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP. This enables the terminal device to generate and send a second address resolution response to its downstream device based on the second NAS message. The downstream device then sends a unicast message to the uplink device corresponding to the destination IP. The second address resolution response includes the MAC address of the uplink device corresponding to the destination IP.

8. A message transmission system, characterized in that, Includes core network EPC and at least one terminal device; The core network EPC is used to encapsulate the first destination IP in the address resolution request sent by the uplink device in an air interface paging message, and broadcast the air interface paging message to at least one of the terminal devices through the base station; The terminal device is used to send a resolution request encapsulated with the first destination IP to each of the downstream devices of the terminal device, and in response to receiving the first address resolution reply sent by the downstream device, sends a NAS message to the core network EPC. The first address resolution reply includes the first destination IP and the MAC address of the downstream device, and the NAS message includes the first destination IP and the device identifier of the terminal device. After receiving the NAS message, the core network EPC sends a second address resolution response to the uplink device. The second address resolution response includes the first destination IP and the MAC address of the PGW of the core network EPC, so that the uplink device sends a unicast message with the MAC address of the PGW as the destination MAC address.

9. The system according to claim 8, characterized in that, The core network EPC is also used to: receive a unicast message encapsulated with the first destination IP sent by the uplink device using the MAC address of the PGW as the proxy address, obtain the device identifier of the terminal device based on the first destination IP, and send the unicast message to the terminal device; The terminal device is further configured to: after receiving the unicast message, forward the unicast message to the downstream device based on the first destination IP.

10. The system according to claim 8, characterized in that, The terminal device is further configured to: receive an address resolution request including a second destination IP sent by any of the downstream devices; encapsulate the second destination IP in a first NAS message; and send the first NAS message to the core network EPC via the base station; The core network EPC is also used to broadcast the address resolution request encapsulated with the second destination IP to each uplink device of the core network EPC, and after receiving the MAC address of the uplink device corresponding to the destination IP sent by the uplink device, send a second NAS message to the terminal device. The second NAS message includes the second destination IP, the MAC address of the PGW of the core network EPC, and the MAC address of the uplink device corresponding to the destination IP. The terminal device is further configured to generate and send an address resolution reply encapsulated with the MAC address of the uplink device corresponding to the second destination IP to the downstream device after receiving the second NAS message, so that the downstream device can send a unicast message to the uplink device corresponding to the destination IP.

11. The system according to claim 8 or 9, characterized in that, The system further includes: the uplink device and / or the downlink device, wherein the uplink device is connected to the core network EPC via Ethernet communication, and the downlink device is connected to the terminal device via a local area network; The uplink device is used to receive the second address resolution reply and then send a unicast message encapsulated with the destination IP address using the MAC address of the PGW as the proxy address. After receiving the second address resolution request, the downstream device, upon confirming that the destination IP is the device IP of the downstream device, generates and sends the first address resolution response to the terminal device.

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