WO2009003394A1

WO2009003394A1 - Method for studying mac address and network element apparatus

Info

Publication number: WO2009003394A1
Application number: PCT/CN2008/071439
Authority: WO
Inventors: Fuhong Xu
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2007-06-29
Filing date: 2008-06-26
Publication date: 2009-01-08
Also published as: CN101075933A; CN100490411C

Abstract

A method for studying a MAC address comprises: in the received ARP reply message with multi identical source IP addresses and different source MAC address, the VRRP standby router can detect the ARP reply message whose source IP address is not the IP address of the current router, but whose source MAC address is the virtual MAC address of the current router; wherein, the format of the virtual MAC address is 00-00-5E-00-01-{VRID}; according to the mapping relation between the MAC address in the hardware address resolution protocol list and the IP address in the software address resolution protocol list, the source MAC address in the ARP reply message whose source MAC address is not the virtual MAC address is refreshed into the hardware address resolution protocol list, and the ARP reply message whose source MAC address is the virtual MAC address is neglected. Using the technical scheme can make the standby router study the correct MAC address.

Description

Method for learning MAC address and network element device

This application claims priority to Chinese Patent Application No. 200710129551.8, entitled "Method of Learning MAC Address and Network Element Device", filed on June 29, 2007, the entire contents of which are incorporated herein by reference. In the application.

Technical field

The present invention relates to the field of communications technologies, and in particular, to a method for learning a MAC address and a network element device.

Background technique

In practical applications, the topology of the dual-homing network shown in Figure 1 is often used. The access gateway (AG) is connected to the two access switches SA and SB through two links, and the two access switches SA and SB are respectively connected to the two access routers RA and RB. In order to solve the problem of how the AG device selects between RA and RB, the Virtual Router Redundancy Protocol (VRRP) is introduced. The VRRP protocol forms a group of routers on the LAN to form a backup group, which is equivalent to a virtual router. The device AG in the LAN communicates with other networks through this virtual router. VRRP dynamically associates the virtual router with the physical router that carries the transmission service. The physical router acts as the primary router. When the primary router or the primary link fails, VRRP triggers the switching, and the standby router is promoted to the primary router. To take over the business transfer work. Referring to Figure 1, it can be assumed that the RA acts as the primary router and the RB acts as the standby router.

Assume that the ARP proxy (ARP Proxy) is enabled on the E1 port of the RA. The method for learning the MAC address before the switchover provided by the prior art is:

When the aging time is reached, the RB initiates an ARP request to the RA and the AG. The default aging time is 20 minutes. After receiving the ARP request packet, the AG sends an ARP reply packet to the RB. The source IP address of the ARP reply packet is the IP address of the AG. The source MAC address is the MAC address of the AG. In this case, the RB can learn the correct one. The MAC address of the AG is used to flush the MAC address of the AG in the ARP reply packet to the pre-stored ARP entry. The ARP entry is a hardware address resolution protocol table, and is used to store the MAC address of the AG connected to the RB. Because the RA is the primary router of the VRRP, and the ARP proxy is enabled on the E1 port, the RA sends an ARP reply message to the RB after receiving the ARP request packet sent by the RB. The ARP reply is the source IP address of the ARP reply. It is the IP address of the AG, and the source MAC address is the VRRP virtual MAC address. If multiple RA devices are attached to the RA and RB The RA sends multiple such ARP reply messages to the RB. The virtual MAC address can be 00-00-5E-00-01-{VRID}, and the RB refreshes the virtual MAC address to the ARP entry. The ARP entry stores the MAC address of the original AG. The address is refreshed to a virtual MAC address. The path in which the RB sends an ARP request to the RA and the RA sends the ARP reply to the RB is as shown by the thick solid line in FIG. 2, and the path in which the RB sends an ARP request to the AG and the ARP sends an ARP reply to the RB. The dotted line in 2 is shown.

In the process of implementing the present invention, the inventor has found that at least the following problems exist in the prior art: The prior art first refreshes the source MAC address in the ARP reply packet from the AG into the ARP entry, and then restores the ARP reply from the RA. The virtual MAC address in the packet is updated to the ARP entry. The content of the ARP entry is changed from the MAC address of the original AG to the virtual MAC address. As a result, the MAC address of the AG is learned incorrectly. When the primary router RA fails or the primary link fails, the E1 port of the RA goes down, and the standby router RB rises to the primary router. The transmission path of the packet is as shown in Figure 1, and the downlink packet is the router RC. To the AG. If the RB is in the ARP entry, the MAC address of the AG is incorrectly learned. Therefore, the downlink packet received by the RB cannot be found in the ARP entry until the next aging time arrives to obtain the correct MAC address of the AG. The MAC address of the AG directly discards the downlink packet and interrupts the transmission of the downlink packet.

Summary of the invention

The embodiment of the invention provides a method for learning a MAC address and a network element device, so as to achieve the purpose of the standby router correctly learning the MAC address.

In view of this, the embodiments of the present invention provide:

A method of learning a MAC address, including:

Receiving an address resolution protocol ARP reply packet group, where the ARP reply packet group includes: a first type ARP reply message and a second type ARP reply message; wherein the first type ARP reply message is a source MAC address An ARP reply packet that is not a virtual MAC address, and the second type of ARP reply packet is an ARP reply packet whose source MAC address is a virtual MAC address.

Determining, in the first type of ARP reply message, the first type of ARP reply message, the first type of ARP reply message is obtained in the ARP reply message group. The source MAC address is flushed to the hardware address resolution protocol table. A network element device, the device comprising:

The ARP reply packet receiving unit is configured to receive an address resolution protocol ARP reply packet group, where the ARP reply packet group includes: a first type ARP reply packet and a second type ARP reply packet; wherein, the A type of ARP reply message is an ARP reply message whose source MAC address is not a virtual MAC address, and the second type of ARP reply message is an ARP reply message whose source MAC address is a virtual MAC address.

The first type of ARP reply message obtaining unit is configured to obtain the first type of ARP reply message when the ARP reply message is the first type of ARP reply message;

The first type of ARP reply message refreshing unit is configured to refresh the obtained source MAC address in the first type of ARP reply message into the hardware address resolution protocol table.

When the packet in the ARP reply packet group is the first type of ARP reply packet, the first type of ARP reply packet is obtained, and the source MAC address in the packet is refreshed to the hardware address resolution. In the protocol table, the MAC address of the gateway that is learned by the standby router is correct, that is, the MAC address of the correct gateway is stored in the hardware address resolution protocol table. When the primary router fails or the primary link fails, and the standby router rises to the primary router and receives the downlink packet, it can find the MAC address of the gateway connected to the correct standby router from the hardware address resolution protocol table. The gateway transmits the downlink message, and does not interrupt the transmission of the downlink message.

DRAWINGS

1 is a dual-homed network diagram provided by the prior art;

2 is a transmission path diagram of an ARP packet provided by the prior art;

3 is a flowchart of a method for learning a MAC address according to an embodiment of the present invention;

4 is a flowchart of a method for learning a MAC address according to another embodiment of the present invention;

FIG. 5 is a structural diagram of a network element device according to another embodiment of the present invention; FIG.

FIG. 6 is a structural diagram of a network element device according to another embodiment of the present invention.

detailed description

Referring to FIG. 1 and FIG. 3, an embodiment of the present invention provides a method for learning a MAC address, and a topology structure of the dual-homing network to which the method is applied is shown in FIG. 1 . The gateway AG is connected to the two access switches SA and SB through two links respectively, and the two access switches SA and SB are respectively connected to the two access routers RA and RB, assuming that the RA acts as the primary router, the RB As a backup router. Methods for learning MAC addresses include:

301. When the aging time arrives, the standby router RB actively sends an ARP request to the AGs connected to the RA and the RB, and receives ARP reply packets from the AG and the RA to form an ARP reply packet.

302. In the ARP reply packet group, find the ARP reply packet with the same source IP address, and return the ARP reply packet with the same source IP address to the corresponding group. At this point, the ARP reply message group consists of multiple groups, and the ARP reply in each group has the same source IP address.

For the case where the IP address of the AG changes, according to the routing protocol, the RA can know the new IP address of the AG in time. Therefore, the source IP address in the ARP reply from the RA is the current IP address of the AG. Therefore, in the received ARP reply packet group, the ARP reply packets with the same source IP address are found in the corresponding group. At this time, the ARP reply message group consists of multiple groups. Two ARP reply messages in each group are from the RA and the other one is from the AG.

303. Determine whether each packet in each group is a first type ARP reply message or a second type ARP reply message, and if it is a first type ARP reply message, execute 304; if it is a second type ARP reply message , then execute 305.

The first type of ARP reply packet is an ARP reply packet whose source MAC address is not the virtual MAC address, that is, the source IP address is the IP address of the AG, and the source MAC address is the ARP reply packet of the MAC address of the AG. The second type of ARP reply message is that the source MAC address is the ARP reply packet of the virtual MAC address, that is, the source IP address is the IP address of the AG, and the source MAC address is the ARP reply packet of the virtual MAC address.

In the 303, the source MAC address in each packet is used to determine whether each packet in each group is a first type ARP reply message or a second type ARP reply message. If the source MAC address of the ARP reply packet is not the virtual MAC address but the MAC address of the AG, the ARP reply packet is the first type of ARP reply packet. If the source MAC address in the ARP reply packet is a virtual MAC address, the ARP reply packet is a second type of ARP reply packet.

304. Obtain a first type of ARP reply message, and then execute 306.

305. Obtain a second type of ARP reply message, and then execute 306.

306. Refresh the source MAC address in the second type of ARP reply to the hardware address resolution protocol table according to the preset refresh time of the second type ARP reply message. The hardware address resolution protocol table and the software address resolution protocol table are preset on the RB, and the correct hardware address resolution protocol table should store the MAC address of the AG, and the software address resolution protocol table is used to store the IP address of the AG in the hardware address resolution protocol table. The MAC address is mapped to the IP address in the software address resolution protocol table. If the IP address of the AG changes, the RB can know the new IP address of the AG in time, and automatically refresh the new IP address of the AG to the software address resolution protocol table to ensure the AG in the software address resolution protocol table. The IP address is the correct IP address of the AG.

The specific implementation process of the source MAC address in the second type of ARP reply message being refreshed to the hardware address resolution protocol table is as follows: The source IP address in the second type of ARP reply message is found in the software address resolution protocol table, according to the pre- The mapping between the MAC address in the hardware address resolution protocol table and the IP address in the software address resolution protocol table, and the source MAC address in the second type ARP reply packet, that is, the virtual MAC address, is flushed to the hardware address resolution protocol. In the table. At this time, the contents stored in the hardware address resolution protocol table are incorrect.

307. Refresh the source MAC address in the first type of ARP reply packet to the hardware address resolution protocol table according to the preset refresh time of the first type of ARP reply packet.

The refresh time of the second type of ARP reply message is set in advance on the RB before the refresh time of the first type of ARP reply message, and the refresh time may be in the ms level or the s level. The starting point of the refresh time may be: After obtaining the second type of ARP reply message.

The specific implementation process of flushing the source MAC address in the first type of ARP reply packet to the hardware address resolution protocol table is as follows:: Find the source IP address in the first type of ARP reply packet in the software address resolution protocol table, according to The mapping between the MAC address in the preset hardware address resolution protocol table and the IP address in the software address resolution protocol table is used to refresh the source MAC address in the first type of ARP reply packet to the hardware address resolution protocol table.

In the above embodiment, there may be no 302, and in 303, it is directly determined whether the packet in the ARP reply packet is a first type ARP reply message or a second type ARP reply message, which does not affect the implementation of the present invention. Refresh to the hardware address resolution protocol table, and then refresh the first type of ARP reply packet whose source MAC address is not the virtual MAC address to the hardware address resolution protocol table, so that the standby router RB can learn correctly. The MAC address of the AG, that is, the MAC address stored in the hardware address resolution protocol table is the correct AG. When the primary router fails or the primary link fails, the standby router RB rises to receive the downlink packet from the primary router, and then finds the correct MAC address of the AG from the hardware address resolution protocol table, and transmits the downlink packet to the AG. , will not interrupt the transmission of downlink messages.

Referring to FIG. 4, another embodiment of the present invention provides a method for learning a MAC address, where the method includes:

401. When the aging time arrives, the standby router RB actively sends an ARP request to the AG connected to the RA and the RB, and receives the ARP reply packet from the AG and the RA to form an ARP reply packet.

402-405 is the same as 302-305, and will not be described here.

406. Delete the second type of ARP reply packet obtained in 405.

407. Refresh the source MAC address in the first type of ARP reply packet to the hardware address resolution protocol table.

Wherein, 406 may be executed after 407 or concurrently with 407, without affecting the implementation of the present invention.

In the embodiment of the present invention, the foregoing 402 may be omitted, and in the 403, the message in the ARP reply packet group is directly determined to be the first type of ARP reply message or the second type of ARP reply message, which does not affect the implementation of the present invention.

The foregoing embodiment may also be implemented in the following manner: When the aging time arrives, the standby router RB actively initiates an ARP request to the AG that is connected to the RA and the RB, and first receives the ARP reply message from the AG, and determines the ARP reply from the AG. The source MAC address in the text determines that the ARP reply packet is the first type of ARP reply packet, and the source MAC address in the first type of ARP reply packet is flushed to the hardware address resolution protocol table; and the ARP reply message from the RA is received. The source MAC address in the ARP reply packet from the RA is determined to determine that the ARP reply packet is the second type of ARP reply packet, and the second type of ARP reply packet is deleted. Delete, the first type of ARP reply packet whose source MAC address is not the virtual MAC address is flushed to the hardware address resolution protocol table, so that the standby router RB can learn the correct MAC address of the AG, that is, the hardware address resolution protocol table stores The correct MAC address of the AG. When the primary router fails or When the primary link fails, the standby router RB rises to receive the downlink packet from the primary router, and can find the correct MAC address of the AG from the hardware address resolution protocol table, and transmits the downlink to the AG. Interrupt the transmission of downlink messages.

A person skilled in the art can understand that all or part of the method for implementing the above embodiments can be completed by a program to instruct related hardware, and the program can be stored in a computer readable storage medium, such as: ROM/RAM, disk. , CD, etc.

Referring to FIG. 5, another embodiment of the present invention provides a network element device, where the device includes: an ARP reply packet receiving unit 501, a determining unit 502, a first type ARP reply packet obtaining unit 503, and a first type ARP reply. Message refreshing unit 504;

The ARP reply packet receiving unit 501 receives the ARP reply packet group, and the ARP reply packet group includes: a first type ARP reply message and a second type ARP reply message; wherein, the first type ARP reply message The ARP reply packet whose source MAC address is not the virtual MAC address, and the second type of ARP reply packet is the ARP reply packet whose source MAC address is the virtual MAC address. The determining unit 502 determines each of the received ARP reply packet groups. Whether the message is the first type of ARP reply message or the second type of ARP reply message; the first type of ARP reply message obtaining unit 503, when the judgment result of the determining unit 502 is the first type of ARP reply message, obtain the first The first type of ARP reply message refreshing unit 504 is configured to refresh the source MAC address in the obtained first type ARP reply message into the hardware address resolution protocol table.

Between the ARP reply packet receiving unit 501 and the determining unit 502, the device further includes: a scribing unit 505, configured to search for the same source IP address in the received ARP reply group

The ARP replies to the packet, and the ARP reply packet with the same source IP address is found to be the corresponding group. The determining unit 502 determines whether the packet in the ARP reply packet group is the first type of ARP reply packet or the second type. The ARP reply message is specifically: It is judged whether the message classified in each group is the first type ARP reply message or the second type ARP reply message.

The device also includes:

The second type ARP reply message obtaining unit 506 obtains the second type ARP reply message when the judgment result of the determining unit 502 is the second type ARP reply message.

a refresh time setting unit 507, configured to set a refresh time of the second type of ARP reply message before the refresh time of the first type of ARP reply message; The second type of ARP reply message refreshing unit 508 is configured to refresh the virtual MAC address in the obtained second type ARP reply message to the hardware address resolution protocol table in the refresh time of the second type of ARP reply message.

The first type ARP reply packet refreshing unit 504 refreshes the source MAC address in the obtained first type ARP reply packet to the hardware address resolution protocol table, specifically: the refresh time of the first type ARP reply packet that is set, The source MAC address in the obtained first type ARP reply packet is flushed to the hardware address resolution protocol table.

The second type ARP reply packet refreshing unit 508 in the embodiment of the present invention first refreshes the second type ARP reply packet whose source MAC address is the virtual MAC address according to the refresh time of the second type ARP reply packet set in advance. The hardware address resolution protocol table, the first type ARP reply message refreshing unit 504 refreshes the first type ARP reply message whose source MAC address is not the virtual MAC address, according to the preset refresh time of the first type ARP reply message. The hardware address resolution protocol table enables the standby router RB to learn the correct MAC address of the AG, that is, the MAC address of the correct AG is stored in the hardware address resolution protocol table. When the primary router fails or the primary link fails, the standby router RB rises to receive the downlink packet from the primary router, and then finds the correct MAC address of the AG from the hardware address resolution protocol table, and transmits the downlink packet to the AG. , will not interrupt the transmission of downlink messages.

Referring to FIG. 6, another embodiment of the present invention provides a network element device, where the device includes: an ARP reply packet receiving unit 601, a determining unit 602, a first type ARP reply packet obtaining unit 603, and a first type ARP reply. The message refreshing unit 604, the grouping unit 605, the second type of ARP reply message obtaining unit 606, the above-mentioned unit function and the connection relationship are the same as those in the third embodiment, and the details are not described herein again;

The second type ARP reply message deleting unit 607 deletes the obtained second type ARP reply message. The second type ARP reply message deleting unit 607 in the embodiment of the present invention deletes the second type ARP reply message whose source MAC address is the virtual MAC address, and the first type ARP reply message refreshing unit 604 sets the source MAC address to be virtual. The first type of ARP reply packet of the MAC address is flushed to the hardware address resolution protocol table, so that the standby router RB can learn the correct MAC address of the AG, that is, the MAC address of the correct AG is stored in the hardware address resolution protocol table. When the primary router fails or the primary link fails, and the standby router RB rises to receive the downlink packet for the primary router, it can The MAC address of the correct AG is found in the hardware address resolution protocol table, and the downlink packet is transmitted to the AG without interrupting the transmission of the downlink packet. The description of the present invention is not limited to the scope of the present invention.

Claims

Rights request

A method for learning a MAC address, comprising:

Receiving an address resolution protocol ARP reply packet group, where the ARP reply packet group includes: a first type ARP reply message and a second type ARP reply message; wherein the first type ARP reply message is a source MAC address The ARP reply packet is not a virtual MAC address, and the second type of ARP reply packet is an ARP reply with a source MAC address being a virtual MAC address.

Determining, in the first type of ARP reply message, the first type of ARP reply message, the first type of ARP reply message is obtained in the ARP reply message group. The source MAC address is flushed to the hardware address resolution protocol table.

2. The method of claim 1 wherein:

Before the source MAC address in the first type of ARP reply packet is flushed to the hardware address resolution protocol table, the method further includes:

Determining, when the packet in the ARP reply packet group is the second type of ARP reply packet, obtaining the second type of ARP reply packet;

Setting a refresh time of the second type of ARP reply message before the refresh time of the first type of ARP reply message;

And refreshing, in the refresh time of the second type of ARP reply message, the obtained virtual MAC address in the second type of ARP reply message to the hardware address resolution protocol table;

Refreshing the source MAC address in the first type of ARP reply packet to the hardware address resolution protocol table is specifically:

The source MAC address in the obtained first type ARP reply message is flushed to the hardware address resolution protocol table in the refresh time of the first type ARP reply message.

3. The method of claim 1 wherein:

The method also includes:

The obtained second type ARP reply message is deleted.

The method according to claim 1, 2 or 3, further comprising: determining whether each packet in the ARP reply packet group is the first type ARP reply packet or It belongs to the second type of ARP reply message.

5. The method of claim 4, wherein:

Before determining whether the packet in the ARP reply packet group is the first type of ARP reply message or the second type of ARP reply message, the method further includes:

In the ARP reply packet group, the ARP reply packet with the same source IP address is searched, and the ARP reply packet with the same source IP address is classified into the corresponding group;

Determining whether each packet in the ARP reply packet group is a first type ARP reply message or a second type ARP reply message is specifically:

It is determined whether the packet in the group is a first type ARP reply message or a second type ARP reply message.

6. A network element device, comprising:

7. Apparatus according to claim 6 wherein:

The device also includes:

The second type of ARP reply message obtaining unit is configured to obtain the second type of ARP reply message when the ARP reply message is the second type of ARP reply message;

a refresh time setting unit, configured to set a refresh time of the second type of ARP reply message before the refresh time of the first type of ARP reply message;

And a second type of ARP reply message refreshing unit, configured to refresh the obtained virtual MAC address in the second type of ARP reply message to the hardware in the refresh time of the set second type ARP reply message Address resolution protocol table; The first type of ARP reply message refreshing unit refreshes the source MAC address in the first type of ARP reply message to the hardware address resolution protocol table: The source MAC address in the obtained first type ARP reply packet is flushed to the hardware address resolution protocol table.

8. Apparatus according to claim 6 wherein:

The device also includes:

The second type of ARP reply message deleting unit is configured to delete the obtained second type ARP reply message.

9. The device according to claim 6, 7 or 8, further comprising:

The determining unit is configured to determine whether each packet in the ARP reply packet group is a first type ARP reply message or a second type ARP reply message.

10. Apparatus according to claim 9 wherein:

The device further includes: between the ARP reply packet receiving unit and the determining unit, the device further includes:

The mapping unit is configured to: in the received ARP reply group, search for ARP reply packets with the same source IP address, and assign the ARP reply packets with the same source IP address to the corresponding group; The determining unit determines whether each packet in the ARP reply packet group is a first type ARP reply message or a second type ARP reply message is: determining that the packet in the group is a first type ARP reply The message is still the second type of ARP reply message.