WO2021184862A1 - Message sending method, first network device, and network system - Google Patents

Abstract

Disclosed in embodiments of the present application are a message sending method, a first network device, and a network system, which can implement entry learning of a network device under an M-LAG scene without additionally deploying a synchronous protocol. The method is applied to a first network device; the first network device communicates with a second network device by means of a first member link, and communicates with a third network device by means of a second member link, the first member link and the second member link belonging to the same multichassis link aggregation group. The method comprises: the first network device obtains a first protocol message; the first network device determines whether the first protocol message is a protocol message for generating a forwarding entry; when the first protocol message is the protocol message for generating the forwarding entry, the first network device duplicates the first protocol message to obtain a second protocol message; the first network device sends the first protocol message to the second network device by means of the first member link, and sends the second protocol message to the third network device by means of the second member link.

Description

Message sending method, first network equipment and network system

This application claims the priority of a Chinese patent application filed with the State Intellectual Property Office of China, the application number is 202010195519.5, and the invention title is "a method for sending messages, the first network device and network system" on March 19, 2020. The entire content is incorporated into this application by reference.

Technical field

This application relates to the field of communications, and in particular to a method for sending messages, a first network device, and a network system.

Background technique

Link Aggregation Group (LAG) is a commonly used networking technology to increase bandwidth and improve link reliability. Multichassis Link Aggregation Group (M-LAG) is an extension of LAG and is widely used in cross-device reliability protection scenarios. In the M-LAG network architecture, one network device is connected to two or more network devices through multiple member links, and the multiple member links belong to the same M-LAG.

Before forwarding the message through the M-LAG network architecture, the network devices in the network architecture need to learn the forwarding entries. At present, learning forwarding entries requires additional deployment of synchronization protocols on network devices, which results in poor compatibility.

Summary of the invention

The embodiments of the present application provide a method for sending a message, a first network device, and a network system, which can realize the table entry learning of the network device in the M-LAG scenario without additional deployment of a synchronization protocol.

In the first aspect, an embodiment of the present application provides a method for sending a message. The method is applied to a first network device. The first network device communicates with a second network device via a first member link. The network device also communicates with a third network device via a second member link, and the first member link and the second member link belong to the same M-LAG. The first network device, the second network device, and the third network device may be routers, switches, and so on. The method includes the following steps: the first network device obtains a first protocol message, and determines whether the first protocol message is a protocol message for generating a forwarding entry. When the first protocol message is a protocol message used to generate a forwarding entry, the first network device copies the first protocol message to obtain a second protocol message. The first network device sends the first protocol message to the second network device via the first member link, and sends the first protocol message to the third network device via the second member link. 2. Protocol messages. Since the replication of the first protocol message does not require additional deployment of synchronization protocol implementation, compared with the current technology, the embodiment of the present application ensures that the second network device and the third network device can respectively generate forwarding entries according to the same protocol message. Under the premise, improve compatibility and reduce system overhead.

Optionally, the determining, by the first network device, whether the first protocol message is a protocol message used to generate a forwarding entry includes: the first network device according to a preset field in the first protocol message The value of determines whether the first protocol message is a protocol message used to generate a forwarding entry. Optionally, the preset field is in a header of the first protocol message. Optionally, the preset field includes the protocol number field in the Ethernet packet header; or, the preset field includes the protocol number field in the Ethernet packet header, and Internet Protocol Version 6 (Internet Protocol). version 6, IPv6) The next header field of the message header and the Internet Control Management Protocol Version 6 (Internet Control Management Protocol Version 6, ICMPv6) type field; or, the preset field includes the Internet Protocol IP message The protocol field of the header; or, the preset fields include the next header field and the ICMPv6 type field of the IPv6 header. For related examples, please refer to the specific implementation section, which will not be repeated here.

Optionally, the first protocol message is an Address Resolution Protocol (ARP) message, a Neighbor Discovery (ND) message, and an Internet Group Management Protocol (IGMP) message Or a Multicast Listener Discovery (MLD) message. Of course, the above four types of messages are not agreements on the first protocol message in this application, and those skilled in the art can also determine by themselves according to actual conditions.

In the second aspect, the embodiments of the present application provide a first network device. The first network device communicates with a second network device via a first member link, and the first network device also communicates with a second network device via a second member link. For communication with a third network device, the first member link and the second member link belong to the same cross-device link aggregation group; the first network device includes: a processor configured to obtain a first protocol message , Determining whether the first protocol message is a protocol message for generating a forwarding entry, and when the first protocol message is a protocol message for generating a forwarding entry, copying the first protocol message Message to obtain a second protocol message; a transmitter, configured to send the first protocol message to the second network device via the first member link, and to send the first protocol message to the second network device via the second member link The third network device sends the second protocol message.

Optionally, the determining, by the first network device, whether the first protocol message is a protocol message used to generate a forwarding entry includes: the first network device according to a preset field in the first protocol message The value of determines whether the first protocol message is a protocol message used to generate a forwarding entry.

Optionally, the preset field is in a header of the first protocol message.

Optionally, the preset field includes the protocol number field in the Ethernet packet header; or, the preset field includes the protocol number field in the Ethernet packet header, and the Internet Protocol version 6 IPv6 packet The next header field of the header and the Internet Control Management Protocol version 6 ICMPv6 type field; or, the preset field includes the protocol field of the Internet Protocol IP header; or, the preset field includes the next header field of the IPv6 header And ICMPv6 type field.

Optionally, the first protocol message is an address resolution protocol ARP message, a neighbor discovery ND message, an Internet Group Management Protocol IGMP message, or a multicast listener discovery MLD message.

In a third aspect, an embodiment of the present application provides a network system, the network system includes a first network device, a second network device, and a third network device. The first network device is the first network device in the second aspect. A network device, the second network device is the first network device of the above second aspect, and the third network device is the third network device of the above second aspect.

In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, which is characterized by including instructions, which when run on a computer, cause the computer to execute the message sending method of the first aspect.

Description of the drawings

FIG. 1 is a schematic structural diagram of a system 100 provided by an embodiment of the application;

FIG. 2 is a flowchart of a method for sending a message according to an embodiment of the application;

FIG. 3 is a structural block diagram of a message sending device 300 provided by an embodiment of the application;

FIG. 4 is a schematic diagram of the hardware structure of the first network device 400 according to an embodiment of the application.

Detailed ways

With the current technology, the forwarding entry in the M-LAG scenario requires an additional synchronization protocol to be deployed on the network device, and the compatibility is poor.

For example, network device A is connected to network device B through member link 1 and connected to network device C through member link 2, and member link 1 and member link 2 belong to the same M-LAG. Since network device B and network device C respectively configure the same Internet Protocol (IP) address and Media Access Control (MAC) on the logical interfaces of their respective M-LAGs, for network device A Unaware network device B and network device C are two network devices, that is, from the point of view of network device A, network device B and network device C are one network device.

Currently, when network device A sends a message, it needs to select a member link from member link 1 and member link 2 through a hash algorithm for forwarding. The principle of the hash algorithm can be either a packet-by-packet hash or a stream-by-stream hash.

The so-called packet-by-packet hashing means that when a packet is sent on the LAG port, the LAG member link for each packet is calculated and selected to send the packet. The purpose of this method is to balance the load of each member link. When the bandwidth of each member link is different, the bandwidth can also be used as a factor in the hash algorithm to realize the load distribution of the member links according to the bandwidth. The packet-by-packet hashing method will cause multiple packets of the same flow to be transmitted through different member links of the LAG, which will cause the problem of packet disorder.

The so-called flow-by-flow hashing means that the same member link of the LAG is selected for transmission of the packets of the same flow, thereby avoiding the problem of out-of-sequence of packets in the same flow transmission process of the packet-by-packet hashing. In actual live network deployment, the flow-by-stream hashing method is basically adopted.

Regardless of the above-mentioned hash algorithm, each message is sent through only one member link, including protocol messages used to generate forwarding entries. For example, if the network device A determines to send a certain protocol message through the member link connected to the network device B, the network device C cannot receive the protocol message. Since the protocol message is used to generate forwarding entries, it will cause the problem that only network device B generates forwarding entries, but network device C cannot generate forwarding entries. Since the network device C has not learned the forwarding entry, when the network device C needs to send a data message to the network device A, the corresponding forwarding entry cannot be found, so that the forwarding of the data message cannot be realized.

In order to solve this technical problem, there are currently two solutions. One is to synchronize the forwarding entries generated by the network device B according to the protocol message to the network device C by additionally deploying an entry synchronization protocol on the network device B and the network device C; The other is to synchronize the protocol messages received by network device B to network device C by additionally deploying a message synchronization protocol on network device B and network device C, so that network device C can generate forwarding entries based on the protocol message . Through the above two methods, both network device B and network device C can learn forwarding entries.

However, both of these solutions rely on additional synchronization protocols deployed. When the network device B and the network device C cannot support the additional synchronization protocol, the above problems cannot be solved. Also, running additional synchronization protocols will increase system overhead.

Therefore, in order to solve the above technical problems, the embodiments of the present application provide a message sending method and device, which can realize the table entry learning of the network device in the M-LAG scenario without additional deployment of a synchronization protocol.

To facilitate understanding, the application scenarios of the embodiments of the present application are first introduced.

Refer to FIG. 1, which is a schematic structural diagram of a system 100 provided by an embodiment of the application.

In FIG. 1, the system 100 includes a network device 101, a network device 102 and a network device 103. The network device 101 is connected to the network device 102 via the member link set L1, and the network device 101 is also connected to the network device 103 via the member link set L2. The member link set L1 includes one or more member links, and the member link set L2 also includes one or more member links. The member links in the member link set L1 and the member links in the member link set L2 belong to the same M-LAG.

The network device 101, the network device 102, and the network device 103 may be routers, switches, access devices, gateways, etc., which are not limited in the embodiment of the present application.

Optionally, the network device 101 is connected to a terminal device and serves as a user-side access device; the network device 102 and the network device 103 serve as a user gateway. The network device 101 can send the uplink data message from the terminal device to the network device 102 or the network device 103; the network device 102 or the network device 103 can send the downlink data message to the network device 101, and the network device 101 forwards it to the terminal equipment.

In the embodiment of the present application, both the network device 102 and the network device 103 are in a dual-active state (Active-Active), that is, both can work normally. Before forwarding the data message, the network device 101 may send a protocol message to the network device 102 and the network device 103, and the protocol message is used to generate corresponding forwarding entries in the network device 102 and the network device 103, so that the network device 102 and the network device 103 forward the data message to the network device 101 according to the forwarding entry.

For specific implementation, refer to the message sending method shown in FIG. 2.

Refer to FIG. 2, which is a flowchart of a method for sending a message according to an embodiment of the application.

In FIG. 2, the message sending method provided by the embodiment of the present application includes the following steps:

S201: The first network device obtains the first protocol message.

In the embodiment of the present application, the first network device may be, for example, the network device 101 in the embodiment shown in FIG. 1. In practical applications, the manner in which the first network device obtains the first protocol message may be that the first network device generates the first protocol message itself, or may receive the first protocol message from other devices.

S202: The first network device determines whether the first protocol message is a protocol message used to generate a forwarding entry.

In the embodiment of the present application, the protocol message used to generate the forwarding entry may be a protocol message used for unicast services, for example, an address resolution protocol (ARP) message or a neighbor discovery (Neighbor Discovery, ND) messages, etc.; the protocol messages used to generate forwarding entries can also be protocol messages used for multicast services, such as Internet Group Management Protocol (IGMP) messages or multicast listeners Discovery (Multicast Listener Discovery, MLD) messages, etc.

Specifically, in this embodiment of the present application, the first network device may determine whether the first protocol message is a protocol message used to generate a forwarding entry according to the value of a preset field in the first protocol message. Optionally, the preset field may be in the header of the first protocol message. The preset field can be one field or multiple fields.

For example, the preset field may be the protocol number field of the Ethernet packet header. The value of the protocol number field is the protocol number of the first protocol message. When the value of the protocol number field is 0x0806, it indicates that the first protocol message The message is an ARP message.

For another example, the preset field may be the protocol number field of the Ethernet packet header, the next header field of the Internet Protocol version 6 (IPv6) packet header, and the Internet Control Management Protocol Version 6 (Internet Control Management Protocol Version 6, ICMPv6) type field, when the value of the protocol number field of the Ethernet header is 0x86DD, the value of the next header field of the IPv6 header is 58, and the value of the ICMPv6 type field When it is 135 or 136, it indicates that the first protocol message is an ND message.

The preset field may also be the protocol field of the IP message header. When the value of the protocol field of the IP message header is 2, it indicates that the first protocol message is an IGMP message.

The preset fields can also be the next header field and the ICMPv6 type field of the IPv6 header. When the value of the next header field of the IPv6 header is 58, it means that the first protocol message is an ICMPv6 message. Further, when ICMPv6 When the value of the type field of the message header is 130, 131, or 132, it indicates that the first protocol message is an MLD message.

S203: When the first protocol message is a protocol message used to generate a forwarding entry, the first network device copies the first protocol message to obtain a second protocol message.

S204: The first network device sends the first protocol message to the second network device via the first member link, and sends the first protocol message to the third network device via the second member link. 2. Protocol messages.

In the embodiment of the present application, the second network device is, for example, the network device 102 in the embodiment shown in FIG. 1, and the third network device is, for example, the network device 103 in the embodiment shown in FIG. 1. The first network device may be dual-homed to the second network device and the third network device.

The first member link may be one of the one or more member links connected between the first network device and the second network device. The second member link may be one of the member links of the one or more member links connected between the first network device and the third network device. One or more member links (including the first member link) connecting the first network device and the second network device, and one or more member links (including the second member link) connecting the first network device and the third network device Member links) belong to the same M-LAG. In other words, for the first network device, the second network device and the third network device are not perceived.

When the first network device confirms that the first protocol message is a protocol message for generating a forwarding entry, the first network device copies the first protocol message to obtain the second protocol message. In addition, the first network device sends the first protocol message to the second network device through the first member link to trigger the second network device to generate a corresponding forwarding entry according to the first protocol message. The first network device also sends a second protocol message to the third network device through the second member link to trigger the third network device to generate a corresponding forwarding entry according to the second protocol message.

Optionally, if there are other member links between the first network device and the second network device in addition to the first member link, the first network device may also send the first network device to the second network device through the other member links. Protocol message. For example, if there are two member links between the first network device and the second network device, that is, the first member link and the third member link, then the first network device can copy the first protocol message to obtain the third protocol message. And send the first protocol message to the second network device through the first member link, and send the third protocol message to the second network device through the third member link. The same is true when there are other member links between the first network device and the third network device in addition to the second member link, which will not be repeated here.

Since the replication of the first protocol message does not require additional deployment of synchronization protocol implementations, compared to the current solution above, the embodiment of this application ensures that the second network device and the third network device can generate forwarding tables respectively according to the same protocol message. Under the premise of the item, improve compatibility and reduce system overhead.

Of course, it is understandable that in practical applications, the network devices connected to the first network device may be more than the second network device and the third network device, that is, the first network device can be connected to other network devices in a multi-homing manner, and the first network device can be connected to other network devices. The member link between the network device and other network devices and the member link with the first network device or the member link with the second network device all belong to the same M-LAG. The second network device and the third network device may be regarded as two of the plurality of network devices connected to the first network device.

If there are more than two network devices connected to the first network device, the first network device may respectively send to each network device the protocol message obtained by copying the first protocol message. For example, the network device connected to the first network device further includes a fourth network device, and the first network device and the fourth network device are connected through a fourth member link, then the first network device can copy the first protocol message to obtain the first network device. Four protocol messages, and send the fourth protocol message to the fourth network device through the fourth member link.

S205: The second network device generates a first forwarding entry according to the first protocol message.

In this embodiment of the present application, the first forwarding entries generated by different types of first protocol messages include different contents.

For example, if the first protocol message and the second protocol message are ARP messages, the first forwarding table entry includes the mapping relationship between the destination IP address and the destination MAC address. Specifically, the second network device obtains the source IP address and the source MAC address from the ARP message, and stores the source IP address as the destination IP address in the first forwarding table entry, and stores the source MAC address as the first forwarding table entry The destination MAC address in.

For another example, if the first protocol message and the second protocol message are IGMP messages, the first forwarding table entry includes the mapping relationship between the multicast source address, the multicast group address, and the outbound interface number. Specifically, the second network device obtains the multicast source address and the multicast group address from the IGMP message, and obtains the interface number of the interface that receives the IGMP message, and according to the multicast source address and multicast group address A first forwarding entry is generated with the interface number, and the outgoing interface number in the first forwarding entry is the interface number of the interface through which the second network device receives the IGMP message.

S206: The third network device generates a second forwarding entry according to the second protocol message.

The specific details of the second forwarding entry generated by the third network device are similar to the first forwarding entry generated by the second network device, and will not be repeated here.

Refer to FIG. 3, which is a structural block diagram of a message sending apparatus 300 provided by an embodiment of the application. The message sending apparatus 300 is used to implement the function of the first network device in the embodiment shown in FIG. 2. The message sending device 300 includes a processing unit 301 and a sending unit 302. The processing unit 301 is used to execute S201-S203 in the embodiment shown in FIG. 2, and the sending unit 302 is used to execute S204 in the embodiment shown in FIG. 2.

Specifically, the processing unit 301 is configured to obtain a first protocol message, and determine whether the first protocol message is a protocol message used to generate a forwarding entry, and when the first protocol message is used to generate a forwarding table When the protocol message of the item is selected, copy the first protocol message to obtain the second protocol message.

The sending unit 302 is configured to send the first protocol message to the second network device via the first member link, and send the first protocol message to the third network device via the second member link 2. Protocol messages.

For the specific implementation of the message sending apparatus 300 shown in FIG. 3, please refer to the related description of the first network device in the embodiment shown in FIG. 2, which will not be repeated here.

FIG. 4 is a schematic diagram of the hardware structure of the first network device 400 according to an embodiment of the application. The first network device 400 shown in FIG. 4 can execute the corresponding steps performed by the first network device in the method of the foregoing embodiment and the function of the first network device 300 in the embodiment shown in FIG. 3.

As shown in FIG. 4, the first network device 400 includes a processor 401, a memory 402, an interface 403, and a bus 404. The interface 403 may be implemented in a wireless or wired manner, and specifically may be a network card. The aforementioned processor 401, memory 402, and interface 403 are connected through a bus 404.

The interface 403 may specifically include a transmitter and a receiver, which are used to send and receive information between the first network device and the second network device and the third network device in the foregoing embodiment. For example, the interface 403 is used to support sending a first protocol packet to the second network device; and/or used to support sending a second protocol packet to the third network device. The processor 401 is configured to execute the processing performed by the first network device in the foregoing embodiment. As an example, the processor 401 is configured to support S201-S203 in FIG. 2. The memory 402 includes an operating system and application programs, and is used to store programs, codes, or instructions. When a processor or hardware device executes these programs, codes, or instructions, the processing process involving the first network device in the method embodiment can be completed. Optionally, the memory 402 may include a read-only memory (English: Read-only Memory, abbreviation: ROM) and a random access memory (English: Random Access Memory, abbreviation: RAM). Wherein, the ROM includes a basic input/output system (English: Basic Input/Output System, abbreviation: BIOS) or an embedded system; the RAM includes an application program and an operating system. When the first network device 400 needs to be operated, the system is booted by the BIOS solidified in the ROM or the bootloader in the embedded system to guide the first network device 400 into a normal operating state. After the first network device 400 enters the normal operating state, the application program and the operating system run in the RAM, thereby completing the processing procedure involving the first network device in the method embodiment.

It can be understood that FIG. 4 only shows a simplified design of the first network device 400. In practical applications, the first network device may include any number of interfaces, processors or memories.

In addition, an embodiment of the present application also provides a network system, which includes the first network device, the second network device, and the third network device in the embodiment shown in FIG. 2 or FIG. 3.

The embodiment of the present application provides a computer-readable storage medium, which is characterized by including instructions, which when run on a computer, cause the computer to execute the message sending method executed by the first network device in the embodiment shown in FIG. 2 .

The terms "first", "second", "third", "fourth", etc. (if any) in the description and claims of this application and the above-mentioned drawings are used to distinguish similar objects, without having to use To describe a specific order or sequence. It should be understood that the data used in this way can be interchanged under appropriate circumstances so that the embodiments described herein can be implemented in a sequence other than the content illustrated or described herein. In addition, the terms "including" and "having" and any variations of them are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or device that includes a series of steps or units is not necessarily limited to those clearly listed. Those steps or units may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.

In this application, "at least one item (a)" refers to one or more, and "multiple" refers to two or more. "The following at least one item (a)" or similar expressions refers to any combination of these items, including any combination of a single item (a) or a plurality of items (a). For example, at least one item (a) of a, b, or c can mean: a, b, c, ab, ac, bc, or abc, where a, b, and c can be single or multiple . In this application, "A and/or B" is considered to include A alone, B alone, and A+B.

Those skilled in the art can clearly understand that, for the convenience and conciseness of the description, the specific working process of the above-described system, device, and unit can refer to the corresponding process in the foregoing method embodiment, which will not be repeated here.

In the several embodiments provided in this application, it should be understood that the disclosed system, device, and method can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical module division, and there may be other divisions in actual implementation, for example, multiple units or components may be combined or It can be integrated into another system, or some features can be ignored or not implemented. In addition, the displayed or discussed mutual coupling or direct coupling or communication connection may be indirect coupling or communication connection through some interfaces, devices or units, and may be in electrical, mechanical or other forms.

The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they may be located in one place, or they may be distributed on multiple network units. Some or all of the units may be acquired according to actual needs to achieve the objectives of the solutions of the embodiments.

In addition, each module unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist alone physically, or two or more units may be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of a software module unit.

If the integrated unit is implemented in the form of a software module unit and sold or used as an independent product, it can be stored in a computer readable storage medium. Based on this understanding, the technical solution of the present application essentially or the part that contributes to the existing technology or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium , Including several instructions to make a computer device (which may be a personal computer, a server, or a network device, etc.) execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage media include: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disks or optical disks and other media that can store program codes. .

Those skilled in the art should be aware that, in one or more of the above examples, the functions described in the present invention can be implemented by hardware, software, firmware, or any combination thereof. When implemented by software, these functions can be stored in a computer-readable medium or transmitted as one or more instructions or codes on the computer-readable medium. The computer-readable medium includes a computer storage medium and a communication medium, where the communication medium includes any medium that facilitates the transfer of a computer program from one place to another. The storage medium may be any available medium that can be accessed by a general-purpose or special-purpose computer.

The specific embodiments described above further describe the objectives, technical solutions, and beneficial effects of the present invention in further detail. It should be understood that the above descriptions are only specific embodiments of the present invention.

As mentioned above, the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the embodiments are modified, or some of the technical features are equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present application.

Claims (12)

A method for sending a message, characterized in that the method is applied to a first network device, the first network device communicates with a second network device via a first member link, and the first network device also communicates with a second network device via a second member link. The member link communicates with a third network device, and the first member link and the second member link belong to the same cross-device link aggregation group; the method includes: Acquiring the first protocol message by the first network device; Determining, by the first network device, whether the first protocol message is a protocol message used to generate a forwarding entry; When the first protocol message is a protocol message used to generate a forwarding entry, the first network device copies the first protocol message to obtain a second protocol message; The first network device sends the first protocol message to the second network device via the first member link, and sends the first protocol message to the third network device via the second member link. 2. Protocol messages. The method according to claim 1, wherein the determining by the first network device whether the first protocol message is a protocol message for generating a forwarding entry comprises: The first network device determines whether the first protocol message is a protocol message used to generate a forwarding entry according to the value of a preset field in the first protocol message. The method according to claim 2, wherein the preset field is in a header of the first protocol message. The method according to claim 2 or 3, wherein the preset field includes a protocol number field in an Ethernet packet header; or, the preset field includes a protocol in the Ethernet packet header Number field, the next header field of the Internet Protocol Version 6 IPv6 header and the Internet Control Management Protocol Version 6 ICMPv6 type field; or, the preset field includes the protocol field of the Internet Protocol IP header; or , The preset fields include the next header field and the ICMPv6 type field of the IPv6 packet header. The method according to any one of claims 1 to 4, wherein the first protocol message is an address resolution protocol ARP message, a neighbor discovery ND message, an Internet Group Management Protocol IGMP message, or a multicast reconnaissance message. The listener discovers the MLD message. A first network device, wherein the first network device communicates with a second network device via a first member link, and the first network device also communicates with a third network device via a second member link, The first member link and the second member link belong to the same cross-device link aggregation group; the first network device includes: The processor is configured to obtain a first protocol message, and determine whether the first protocol message is a protocol message used to generate a forwarding entry, and when the first protocol message is a protocol used to generate a forwarding entry When sending a message, copy the first protocol message to obtain the second protocol message; A transmitter, configured to send the first protocol message to the second network device via the first member link, and send the second protocol message to the third network device via the second member link Protocol message. The network device according to claim 6, wherein the first network device determining whether the first protocol message is a protocol message used to generate a forwarding entry comprises: The first network device determines whether the first protocol message is a protocol message used to generate a forwarding entry according to the value of a preset field in the first protocol message. The network device according to claim 7, wherein the preset field is in a header of the first protocol message. The network device according to claim 7 or 8, wherein the preset field includes the protocol number field in the Ethernet packet header; or, the preset field includes the protocol number field in the Ethernet packet header. The protocol number field, the next header field of the Internet Protocol version 6 IPv6 header and the Internet Control Management Protocol version 6 ICMPv6 type field; or, the preset field includes the protocol field of the Internet Protocol IP header; or, The preset fields include the next header field of the IPv6 packet header and the ICMPv6 type field. The network device according to any one of claims 6-9, wherein the first protocol message is an address resolution protocol ARP message, a neighbor discovery ND message, an Internet Group Management Protocol IGMP message, or a multicast The listener found the MLD message. A network system, characterized in that, the network system includes a first network device, a second network device, and a third network device, and the first network device is the one in any one of the claims 6-10 The first network device, the second network device is the first network device in any one of claims 6-10, and the third network device is the first network device in any one of claims 6-10 The third network device. A computer-readable storage medium, characterized by comprising instructions, which when run on a computer, causes the computer to execute the message sending method according to any one of claims 1-5.

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