VPLS fast rerouting method and device

Embodiments of the present invention provide a VPLS fast rerouting method and device. The method includes: generating, by a remote PE, a backup forwarding entry; and when a designated forwarder or a designated forwarder pseudo wire in a multihoming protection group fails, or the designated forwarder is switched in the multihoming protection group, forwarding, by the remote PE, a data packet according to the backup forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to the same VPLS instance, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE.

TECHNICAL FIELD

Embodiments of the present invention relate to the network communications field, and in particular to a Virtual Private Local area network Service (VPLS) fast rerouting method and device.

BACKGROUND

The VPLS is a layer-2 virtual private network VPN (Virtual Private Network) technology based on the Internet Protocol (IP)/Multiprotocol Label Switching (MPLS) and Ethernet. A main purpose of the VPLS is to use a public packet switched network to connect user stations that are separated in physical locations, so that the user stations work as if they are located in a local area network. In a VPLS network, fully-meshed point-to-point pseudo wires PWs (Pseudo Wires) are established between PEs (Provider Edges), and a service provider may provide Ethernet-based multipoint-to-multipoint services for users through an IP/MPLS backbone network. For the purpose of improving reliability of services, normally a CE (Customer Edge) is connected to multiple PEs in the VPLS network through multiple links, which is referred to as multihoming. When a CE-PE link or a PE thereof fails, another link and another PE may still ensure accessibility of services. For the purpose of avoiding a traffic forwarding loop in this networking scenario, one of the multiple PEs connected to the CE is selected as a designated forwarder DF (Designated Forwarder) for traffic forwarding, and meanwhile, through a multihoming information advertisement mechanism or through a manual configuration, a remote PE may learn associations between the multiple PEs connected to the same CE.

According to an existing VPLS processing mechanism, a PE learns Media Access Control (MAC) addresses according to received data packets, and establish a MAC forwarding table. For example, in a VPLS network, fully-meshed PW connections are established between PEs that belong to the same VPLS, where CE1is dual-homed to access PE1and PE2, and pseudo wire connections between the PE1and a remote PE3and between the PE2and the PE3are a PW1and a PW2respectively. After the PE1is elected as a designated forwarder, the PE1is responsible for forwarding data packets sent to the CE1and data packets sent by the CE1, and corresponding MAC addresses learned by the remote PE3from received data packets are associated with the pseudo wire PW1. If the PW1or PE1fails, the PE3broadcasts data packets destined to the CE1to all remote PEs that belong to a same VPLS instance. This will occupy a lot of precious bandwidth resources of the backbone network and processing resources of the PE3.

SUMMARY

An embodiment of the present invention provides a VPLS fast rerouting method, where the method includes:

generating, by a remote PE, a backup forwarding entry according to media access control MAC address information learned from a first pseudo wire, where the MAC address information in the backup forwarding entry is associated with every pseudo wire among non-designated forwarder pseudo wires, a first PE acting as a designated forwarder in a multihoming protection group is connected to the remote PE through the first pseudo wire, and other PEs acting as non-designated forwarders in the multihoming protection group are connected to the remote PE through the non-designated forwarder pseudo wires; and

when the first pseudo wire fails, the first PE fails, or one of the other PEs acting as non-designated forwarders is switched to act as the designated forwarder, forwarding, by the remote PE, a packet by using the backup forwarding entry.

An embodiment of the present invention further provides a VPLS fast rerouting device, where the device includes:

a MAC address information acquiring unit, configured to acquire source media access control MAC address information from a data packet received through a first pseudo wire PW;

a multihoming protection group information acquiring unit, configured to acquire information about a multihoming protection group formed by a first PE acting as a designated forwarder and other PEs acting as non-designated forwarders, where the first PE and the other PEs are connected to the device;

a backup forwarding entry generating unit, configured to generate a backup forwarding entry according to the source MAC address information acquired by the MAC address information acquiring unit and the information about the multihoming protection group acquired by the multihoming protection group information acquiring unit, where the source MAC address information in the backup forwarding entry is associated with every pseudo wire among non-designated forwarder pseudo wires, the first PE in the multihoming protection group is connected to the device through the first pseudo wire, and the other PEs acting as non-designated forwarders are connected to the device through the non-designated forwarder pseudo wires; and

a packet forwarding unit, configured to forward the packet by using the backup forwarding entry when the first PW fails, the first PE fails, or the designated forwarder is switched.

An embodiment of the present invention further provides a VPLS fast rerouting method, where the method includes:

receiving, by a non-designated forwarder PE in a multihoming protection group, MAC forwarding table information sent by a designated forwarder PE;

generating a MAC forwarding entry of the non-designated forwarder PE by replacing an identifier of a pseudo wire connecting the designated forwarder PE and a remote PE in the MAC forwarding table information with an identifier of a pseudo wire connecting the non-designated forwarder PE and the remote PE and/or replacing an identifier of an attachment circuit connecting the designated forwarder PE and a CE in the MAC forwarding table information with an identifier of an attachment circuit connecting the non-designated forwarder PE and the CE; and

when the designated forwarder PE fails, the pseudo wire connecting the designated forwarder PE and the remote PE fails, or the designated forwarder is switched in the multihoming protection group, forwarding, by the PE that receives a data packet and is in the multihoming protection group, the data packet by using the MAC forwarding entry of the PE.

An embodiment of the present invention further provides a VPLS fast rerouting device, where the device includes:

a MAC forwarding table information receiving unit, configured to receive MAC forwarding table information of a designated forwarder PE sent by the designated forwarder PE in a multihoming protection group;

a MAC forwarding entry generating unit, configured to generate a MAC forwarding entry of the fast rerouting device by replacing an identifier of a pseudo wire connecting the designated forwarder PE and a remote PE in the MAC forwarding table information with an identifier of a pseudo wire connecting the fast rerouting device and the remote PE and/or replacing an identifier of an attachment circuit connecting the designated forwarder PE and a CE in the MAC forwarding table information with an identifier of an attachment circuit connecting the fast rerouting device and the CE, where the fast rerouting device is a non-designated forwarder; and

a packet forwarding unit, configured to forward, by the fast rerouting device receiving a data packet, the data packet by using the MAC forwarding entry of the fast rerouting device when the designated forwarder PE in the multihoming protection group or the pseudo wire connecting the designated forwarder PE and the remote PE fails, or the fast rerouting device is switched to act as the designated forwarder.

According to the VPLS fast rerouting method provided in the embodiments of the present invention, a remote PE generates a backup forwarding entry; and when a designated forwarder or a designated forwarder pseudo wire in a multihoming protection group fails, or the designated forwarder is switched in the multihoming protection group, the remote PE forwards a data packet according to the backup forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to a same VPLS instance, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE. By using the preceding VPLS fast rerouting method, the VPLS fast rerouting device provided in the embodiments of the present invention can also achieve the effect of reducing a waste of bandwidth resources in the backbone network and processing resources of the PE.

DESCRIPTION OF EMBODIMENTS

For better understanding of the objectives, technical solutions, and advantages of the embodiments of the present invention, the following describes in further detail the present invention with reference to accompanying drawings.

Referring toFIG. 1, embodiment 1 of the present invention provides a VPLS fast rerouting method, where the method includes:

101. A PE3generates a backup forwarding entry according to MAC address information learned from a PW1, where the MAC address information in the backup forwarding entry is associated with a PW2, a PE1and a PE2form a multihoming protection group and are connected to the PE3through the PW1and the PW2respectively, and, in the multihoming protection group, the PE1is selected as a designated forwarder, and the PE2is a non-designated forwarder.

As shown inFIG. 2, the PE1, the PE2, the PE3, a PE4, and a PE5, and a CE1, a CE2, and a CE3belong to a same VPLS. The CE1is dual-homed to access the PE1and the PE2through an AC1and an AC2respectively, and the PE1and the PE2are connected to the PE3through the PW1and the PW2respectively, where the PE1and the PE2form a multihoming protection group. Through a multihoming information advertisement mechanism or through a manual configuration, the PE3learns that the PE1and the PE2belong to the same multihoming protection group and that the PE1and the PE2are multihomed PEs of the CE1. In the multihoming protection group, one PE is selected as a designated forwarder, and the other PE is a non-designated forwarder. For example, if the PE1is selected as a designated forwarder, the PE2is a non-designated forwarder. Here the PW2between the PE2and the PE3may be referred to as a non-designated forwarder pseudo wire. Because the PE2is a non-designated forwarder, an AC2between the PE2and the CE1is in blocked state. The CE1sends a data packet destined to the CE2to the PE1through an AC1; the PE1sends the data packet to the PE3through the PW1according to a MAC forwarding entry of the PE1; when the PE3receives the data packet from the CE1through the PW1, the PE3learns a source MAC address from the received data packet, where the source MAC address may exemplarily be a MAC address of the CE1, and may also be a MAC address of a customer device (not illustrated in the figure) connected to the CE1; and the PE3generates a primary forwarding entry according to the learned source MAC address, where the learned source MAC address in the primary forwarding entry is associated with the PW1and is used to guide forwarding of the data packet whose destination MAC address is the CE1or a customer device connected to the CE1. In addition, the PE3binds the source MAC address learned from the data packet received through the PW1with the pseudo wire PW2to generate a backup forwarding entry.

For example, when the PE3receives a data packet whose source MAC address is HH-HH-HH-HH-HH-HH from the PW1, the PE3generates a primary forwarding entry, where the MAC address HH-HH-HH-HH-HH-HH in the primary forwarding entry is associated with the PW1; meanwhile, the PE3further generates a backup forwarding entry, where the HH-HH-HH-HH-HH-HH in the backup forwarding entry is associated with the PW2.

102. When the PW1or the PE1fails or when it is learned that the DF is switched to the PE2, the PE3forwards the packet by using the backup forwarding entry.

For example, the PE3may use a detection mechanism, such as BFD or LSP-Ping, to detect failures of the PW1and the PE1; when the PE3detects that the PW1or the PE1fails, or the PE3receives from the PE1or PE2a notification that the DF is switched to the PE2, the PE3does not wait for a process of relearning the MAC address, but directly sends, by using the backup forwarding entry, data by unicast through the PW2. For example, if, when the PE3receives from the CE2a data packet whose destination address is the MAC address of the CE1or whose destination address is the MAC address of the customer device connected to the CE1, the PE3detects that the PW1fails, or detects that the PE1fails, or learns that the DF is switched to the PE2, the PE3queries the backup forwarding entry and finds that the destination address of the data packet is bound with the PW2, and therefore, sends the data packet to the PW2by unicast, thereby avoiding broadcasting the data packet destined to the CE1to all provider edge devices PE1, PE2, PE4, and PE5that belong to the same VPLS, and further reducing an unnecessary waste of bandwidth resources in a backbone network and processing overhead.

If, when the PE2receives from the PE3a data packet destined to the CE1or the customer device connected to the CE1, the PE2is switched to act as the designated forwarder, because the PE2has not learned the MAC address of the CE1and the MAC address of the customer device connected to the CE1, the PE2broadcasts the data packet received through the PW2to all local interfaces AC2and AC3that belong to a same VPLS instance, thereby causing a waste of bandwidth resources and processing resources; and if, in this case, the PE2is not switched to act as the designated forwarder, an attachment circuit AC between the PE2and the CE1is still in blocked state, and the PE2cannot send the data packet to the CE1through the attachment circuit AC2, thereby causing an interruption of the service. For a CE1side, when the PE2is selected as a new designated forwarder because the AC1, the PW1, or the PE1fails, the CE1sends, by using the AC2, the data packet destined to the CE2to the PE2, and at this time, the PE2has not learned MAC address information of a remote PE through a data plane, and therefore, can only send the data packet to all remote PEs that belong to the same VPLS in a broadcasting manner, namely, PE3-PE5, thereby causing a waste of bandwidth resources in the backbone network and processing resources of the PE2.

To avoid the preceding problem, synchronization of MAC forwarding table information may be performed between the dual-homed PE1and PE2of the CE1; when the PE2receives a data packet whose destination address is a MAC address of the CE2or whose destination address is a MAC address of a customer device connected to the CE2, the PE2directly forwards, by using the MAC forwarding table information synchronized from the PE1, data to the PE3by unicast, without broadcasting it to the PE3, PE4, and PE5that belong to the same VPLS; when the PE2receives a data packet whose destination address is a MAC address of the CE1or whose destination address is a MAC address of a customer device connected to the CE1, the PE2directly forwards, by using the MAC forwarding table information synchronized from the PE1, data to the AC2by unicast, without broadcasting it to the AC2and AC3that belong to the same VPLS. The synchronization of MAC forwarding table information includes synchronization of AC-side MAC address information and synchronization of PW-side MAC address information. Synchronization of MAC forwarding table information between the PE1and the PE2may be implemented by extending an existing control protocol and may also be implemented by defining a new control protocol. For example, a state interaction protocol may run between the PE1and the PE2and the state interaction protocol is extended to implement synchronization of MAC forwarding table information between the PE2and the PE1. The specific operation is as follows: The PE1acting as a designated forwarder synchronizes the MAC forwarding table information learned from the AC1and the MAC forwarding table information learned from the PW1to the PE2, and the PE2generates a corresponding MAC forwarding entry. For example, the Inter-Chassis Communications Protocol ICCP (Inter-Chassis Communication Protocol) may be extended to implement synchronization of the MAC forwarding table information between the PE1and the PE2. For example, an application specific type-length-value Application Specific TLV in a redundancy protection group application data message RG Application Data Message of the ICCP protocol is used to carry the MAC forwarding table information to synchronize the MAC forwarding table information between the PE1and the PE2. The format of the RG Application Data Message is shown inFIG. 3, where the Application Specific TLV may carry particular application specific information. For example, two methods may be used to extend the ICCP protocol to synchronize the MAC forwarding table information between the PE1and the PE2:

Method 1: Two application type-length-values are defined: PW-RED MAC TLV and mLACP MAC TLV, where the PW-RED MAC TLV is used to carry MAC address information learned from a PW side in the multihoming protection group, and the mLACP MAC TLV is used to carry MAC address information learned from an AC side in the multihoming protection group.

For example, the Value field in the PW-RED MAC TLV may carry a MAC forwarding entry in the following format:

the Value field in the mLACP MAC TLV may carry a MAC forwarding entry in the following format:

The Action field indicates whether an operation for the MAC forwarding entry is Add or Remove.

The VPLS ID field identifies a VPLS instance to which the MAC forwarding entry belongs.

The VLAN ID field identifies a virtual local area network VLAN (Virtual Local Area Network) to which the MAC forwarding entry belongs.

The VPLS ID and VLAN ID are used to identify a MAC forwarding table to which a synchronized MAC address belongs; the PE generates different MAC forwarding tables according to different VPLS IDs or (VPLS IDs+VLAN IDs). For PEs in the same protection group, synchronization of the MAC address is also performed according to a particular VPLS ID or (VPLS ID+VLAN ID).

The MAC Address field in the PW-RED MAC TLV indicates a MAC address learned from a PW, and the PW ID is a PW identifier associated with the MAC address.

The MAC Address field in the mLACP MAC TLV indicates a MAC address learned from an AC, and the AC ID is a port identifier associated with the MAC address.

Method 2: MAC forwarding table information learned from both an AC side and a PW side is uniformly carried by a newly defined application type-length-value VPLS MAC TLV, where an example of a Value field of the VPLS MAC TLV may be:

The Action field indicates whether an operation for the MAC entry is Add or Remove.

The VPLS ID field identifies a VPLS instance to which the MAC forwarding entry belongs.

The VLAN ID field identifies a VLAN to which the MAC forwarding entry belongs.

The VPLS ID and VLAN ID are used to identify a MAC forwarding table to which a synchronized MAC address belongs; the PE generates different MAC forwarding tables according to different VPLS IDs or (VPLS IDs+VLAN IDs). For PEs in the same protection group, synchronization of the MAC address is also performed according to a particular VPLS ID or (VPLS ID+VLAN ID).

The MAC Address field indicates a learned MAC address; the Interface Type is used to identify whether the MAC address information is learned from an AC-side link or a network-side PW; and the Interface ID identifies an AC link port or PW ID information associated with the carried MAC address information.

In the two preceding methods, the newly defined TLVs may also not carry PW ID or AC ID information, and instead, an existing application TLV is used to provide the information. In this case, the RG Application Data Message for synchronizing MAC forwarding table information needs to carry the newly defined PW-RED MAC TLV, mLACP MAC TLV, or VPLS MAC TLV, and an existing TLV for identifying the PW and that for identifying the AC, for example, “PW ID TLV”, “Generalized PW ID TLV”, or “mLACP Port Config TLV”.FIG. 4is a schematic diagram of a format of an example of an RG Application Data Message for synchronizing MAC forwarding table information when a PW-RED MAC TLV in the message does not include PW ID information. The RG Application Data Message includes a PW ID TLV or a Generalized PW ID TLV in addition to the PW-RED MAC TLV, where either the PW ID TLV or Generalized PW ID TLV may be selected according to deployment of the PW in the network. In this way, if an Application Data Message is used to synchronize multiple pieces of MAC address information learned from a same PW, every Application Data Message needs to carry only one piece of PW ID information, but may carry multiple pieces of MAC address information associated with the PW ID, thereby improving synchronization efficiency of MAC forwarding table information. The format of the RG Application Data Message for synchronizing MAC forwarding table information when the newly defined mLACP MAC TLV does not include AC ID information is similar to that of the RG Application Data Message when the newly defined PW-RED MAC TLV does not include the PW ID information, and the only difference is that the PW ID TLV or the Generalized PW ID TLV in the RG Application Data Message is replaced with the existing TLV that may identify the AC ID, for example, being replaced with the mLACP Port Config TLV defined in ICCP.

After receiving the MAC forwarding table information synchronized from the PE1, the PE2generates, according to the PW ID or AC ID information thereof and multihoming protection group configuration information, a MAC forwarding entry associated with the PW2or the AC2.

For example, when the PE2receives the following information synchronized from the PE1:

because the PW2and the PW1belong to a same multihoming protection group (Redundancy Group), the PE2locally generates the following forwarding entry:

When the PE2receives the following information synchronized from the PE1:

because the AC1and the AC2belong to a same multihoming protection group (Redundancy Group), the PE2locally generates the following forwarding entry:

If, after synchronization of MAC forwarding table information between the PE1and the PE2is completed, the PW1or the PE1fails, for the data packet traffic sent from the CE2to the CE1: if, when the PE2receives a data packet from the PW2, the designated forwarder is switched to the PE2, the PE2may use the local forwarding entry generated according to the MAC forwarding table information synchronized from the PE1to directly forward data to the AC2by unicast, where, for a Qualified learning mode, the PE2performs forwarding to the AC2that belongs to VLAN B of VPLS A, without broadcasting on all ACs that belong to VLAN B of VPLS A, and for an unqualified learning Unqualified learning mode, the PE2performs forwarding to the AC2that belongs to VPLS A, without broadcasting on all ACs that belong to VPLS A; and if, when the data packet traffic from the PW2is received, the PE2is not switched to act as the designated forwarder, for the purpose of avoiding generation of a forwarding loop, the data packet is sent by unicast according to the forwarding entry only when an entry matching a destination MAC address of the data packet can be found in a MAC forwarding table of the PE2, and for an unknown unicast packet, broadcast packet, and multicast packet for which no forwarding entry corresponding to a destination MAC address of the packet cannot be found in the forwarding table, the AC2is still in the blocked state, that is, the PE2does not send the data packet to the AC2. After synchronization of MAC forwarding table information between the PE1and the PE2is completed, because the MAC forwarding table of the PE2includes a forwarding entry where the MAC address of the CE1is associated with the AC2and a forwarding entry where the MAC address of the customer device connected to the CE1is associated with the AC2, the PE2directly forwards, to the AC2by unicast according to a table lookup result of the MAC forwarding table, the data packet whose destination address is the MAC address of the CE1or the MAC address of the customer device connected to the CE1.

For customer data traffic sent from the CE1to the CE2, when the AC1, PE1, or PW1fails, the designated forwarder is switched to the PE2through synchronization of state information, and at this time, the CE1sending, by using the AC2, a data packet to the PE2. Though the PE2has not learned remote MAC address information through the data plane at this time, by using a mechanism that is for synchronizing MAC forwarding table information between the PE1and the PE2provided in this embodiment and where the MAC forwarding table of the PE2includes a forwarding entry that associates the MAC address of the remote CE2and the MAC address of the customer device connected to the CE2with the PW2, and the PE2directly forwards, to the PW2by unicast according to the table lookup result of the MAC forwarding table, the data packet whose destination address is the MAC address of the CE2and the data packet whose destination address is the MAC address of the customer device connected to the CE2, thereby avoiding unnecessary data broadcasting in the backbone network.

For example, after the designated forwarder is switched in the multihoming protection group, the PE switched to act as the designated forwarder may synchronize its MAC forwarding table information to a non-designated forwarder PE in the multihoming protection group; the non-designated forwarder PE generates its MAC forwarding entry according to the received MAC forwarding table information of the designated forwarder PE, so as to guide forwarding of a data packet when a PW fails or the designated forwarder fails. For example, the PE2switched to act as the designated forwarder sends its MAC forwarding table information to the PE1; after receiving the MAC forwarding table information of the PE2, the PE1generates its corresponding MAC forwarding entry to guide forwarding of the data packet when the PW2or the PE2fails or when the PE1is switched again to act as the designated forwarder.

The VPLS fast rerouting method provided in the embodiment of the present invention may also apply to a case that the multihoming protection group includes multiple PEs. As shown inFIG. 5, the multihoming protection group includes three PEs: a PE1, a PE2, and a PE4. The PE1, PE2, and PE4access a PE3through pseudo wires PW1, PW2, and PW3respectively, and a CE1accesses the PE1, PE2, and PE4through attachment circuits AC1, AC2, and AC3respectively. In the multihoming protection group, one PE thereof is selected as a designated forwarder, and other PEs are non-designated forwarders. For example, if the PE1is selected as the designated forwarder, the PE2and PE4are non-designated forwarders. Here the pseudo wires PW2and PW3between the non-designated forwarder PE2and the remote PE3and between the PE4and the PE3are referred to as non-designated forwarder pseudo wires. Because the PE2and the PE4are non-designated forwarders, the AC2and the AC3between the PE2and the CE1and between the PE4and the CE1are in blocked state. The CE1sends a data packet destined to a CE2to the PE1through the AC1; the PE1sends the data packet to the remote PE3through the PW1according to an MAC forwarding entry of the PE1; when the PE3receives the data packet from the CE1through the PW1, the PE3learns a source MAC address from the received data packet, where the source MAC address may exemplarily be a MAC address of the CE1and may also be a MAC address of a customer device (not illustrated in the figure) connected to the CE1; the PE3generates a primary forwarding entry according to the learned source MAC address, where the learned source MAC address in the primary forwarding entry is associated with the PW1and then is used to guide forwarding of the data packet whose destination MAC address is the MAC address of the CE1or whose destination MAC address is the MAC address of the customer device connected to the CE1. In addition, the PE3binds the source MAC address learned from the data packet received through the PW1with the pseudo wires PW2and PW3to generate a backup forwarding entry. For example, when the PE3receives a data packet whose source MAC address is HH-HH-HH-HH-HH-HH from the PW1, the PE3generates a primary forwarding entry, where the MAC address HH-HH-HH-HH-HH-HH in the primary forwarding entry is associated with the PW1; meanwhile, the PE3further generates a backup forwarding entry, where the HH-HH-HH-HH-HH-HH in the backup forwarding entry is associated with the PW2and PW3. When it is detected that the PW1or the PE1fails or when it is learned that the designated forwarder is switched, the PE3forwards the packet by using the backup forwarding entry. For example, the PE3may use a detection mechanism, such as BFD and LSP-Ping, to detect failures of the PW1and the PE1; when the PE3detects that the PW1or the PE1fails, or the PE3receives from the PE1, the PE2, or the PE4a notification that the designated forwarder is switched, the PE3does not wait for a process of relearning the MAC address, but directly sends, by using the backup forwarding entry, the data packet through the pseudo wires PW2and PW3that belong to the same multihoming protection group as the PW1. For example, if, when the PE3receives from the CE2a data packet whose destination address is the MAC address of the CE1or whose destination address is the MAC address of the customer device (not illustrated in the figure) connected to the CE1, the PE3detects that the PW1or the PE1fails but no notification that the designated forwarder is switched is received, the PE3queries the backup forwarding entry, finds that the destination MAC address of the received data packet is bound with the PW2and the PW3, and therefore, sends the data packet to the PW2and PW3respectively; if at this time the PE3has received a notification that the designated forwarder is switched, for example, the designated forwarder is switched to the PE4, the PE3directly sends the data packet to the PW3according to the backup forwarding entry. In the preceding two cases, broadcasting, by the PE3, the data packet destined to the CE1to all PEs that belong to a same VPLS can be avoided, and an unnecessary waste of bandwidth resources in a backbone network and processing overhead can be reduced.

Likewise, in a case that the multihoming protection group includes multiple PEs, synchronization of MAC forwarding table information between the multiple PEs may also be implemented. As shown inFIG. 5, the PE1, the PE2, and the PE4form a multihoming protection group; it is assumed that the PE1in the multihoming protection group is selected as a designated forwarder, and then the PE2and the PE4are non-designated forwarders, for example, it is assumed that the PE1is selected as the designated forwarder, and then the PE2and the PE4are non-designated forwarders. Here the pseudo wires PW2and PW3between the non-designated forwarder PE2and the remote PE3and between the PE4and the PE3are referred to as non-designated forwarder pseudo wires. The PE1acting as the designated forwarder synchronizes MAC forwarding table information learned from the AC1and the MAC forwarding table information learned from the PW1to the non-designated forwarders PE2and PE3in the multihoming protection group; the PE2and the PE3generate their MAC forwarding entries according to the synchronized MAC forwarding table information. Synchronization of MAC forwarding table information between PEs in the multihoming protection group and the method for generating their MAC forwarding entries by the PE2and PE3according to the synchronized MAC forwarding table information are the same as those in the case that the multihoming protection group includes two PEs, and are not further described herein.

If, after synchronization of MAC forwarding table information between the PE1and the PE3and between the PE2and the PE3is completed, the PW1or the PE1fails, for the data packet traffic sent from the CE2to the CE1: if, when the PE4receives a data packet from the PW3, the multihoming protection group has completed switching of the designated forwarder, for example, the designated forwarder is switched from the PE1to the PE4, the PE4may use its MAC forwarding entry generated according to the MAC forwarding table information synchronized from the PE1to directly forward data to the AC3by unicast; and if, when data packet traffic from the PW3is received, the PE4is not switched to act as the designated forwarder, for the purpose of avoiding generation of a forwarding loop, the data packet is sent by unicast according to the forwarding entry only when a forwarding entry matching a destination MAC address of the data packet can be found in a MAC forwarding table of the PE4, and for an unknown unicast packet, broadcast packet, or multicast packet for which no forwarding entry corresponding to the destination MAC address of the packet cannot be found in the forwarding table, the AC3is still in blocked state, that is, the PE4does not send the data packet to the AC3. After synchronization of MAC forwarding table information between the PE1and the PE4and between the PE2and the PE4is completed, because the MAC forwarding table of the PE4includes a forwarding entry where a MAC address of the CE1is associated with the AC3and a forwarding entry where a MAC address of a customer device connected to the CE1is associated with the AC3, the PE4directly forwards, to the AC3by unicast according to a table lookup result of the MAC forwarding table, the data packet whose destination address is the MAC address of the CE1or the MAC address of the customer device connected to the CE1.

For the customer data traffic sent from the CE1to the CE2, when the AC1, the PE1, or the PW1fails, it is assumed that the designated forwarder is switched to the PE4through synchronization of state information, and at this time, the CE1sends a data packet to the PE4by using the AC3. Though the PE4has not learned remote MAC address information through the data plane at this time, by using a mechanism that is for synchronizing MAC forwarding table information between the PE1and the PE4and between the PE2and the PE4provided in this embodiment and where a MAC forwarding table of the PE4includes a forwarding entry that associates a MAC address of the CE2and a MAC address of a customer device connected to the CE2with the PW2, the PE4directly forwards the data packet whose destination address is the MAC address of the CE2and the data packet whose destination address is the MAC address of the customer device connected to the CE2to the PW3by unicast according to the table lookup result of the MAC forwarding table, thereby avoiding unnecessary data broadcasting in a backbone network.

The VPLS fast rerouting method provided in the embodiment of the present invention is also applicable to a scenario where multiple multihoming protection groups have overlapped PEs. As shown inFIG. 6, a PE1and a PE4form a multihoming protection group, and the PE1and a PE2also form a multihoming protection group. Two CE1and CE3belonging to a same VPLS are dual-homed to the two multihoming protecting groups respectively. In both of the two multihoming protection groups, the PE1is selected as a designated forwarder. By using the VPLS fast rerouting method provided in the embodiment of the present invention, a remote PE3generates a backup forwarding entry about the CE1and the CE3in addition to a primary forwarding entry about the CE1and the CE3. In the primary forwarding entry of the PE3, a MAC address of the CE1and that of a customer device connected to the CE1are associated with a PW1, and a MAC address of the CE3and that of a customer device connected to the CE3are associated with the PW1; and in the backup forwarding entry, the MAC address of the CE1and the MAC address of the customer device connected to the CE1are associated with a PW2and a PW3, and the MAC address of the CE3and the MAC address of the customer device connected to the CE3are associated with the PW2and the PW3. When it is detected that the PE1or the PW1fails, the remote PE3receives from a CE2a data packet whose destination address is the MAC address of the CE1or the CE3or whose destination address is the MAC address of the customer device connected to the CE1or the CE3, and therefore the PE3sends the data packet to the PW2and the PW3respectively according to the backup forwarding entry. Here, the PE3needs to send the received data packet to the PW2and the PW3respectively because the PE3can only obtain, by MAC address learning in a the data plane, an association between the MAC addresses of the CE1and the CE3and the PW1and an association between the MAC addresses of the customer devices connected to the CE1and the CE3and the PW1, and the PE3only knows, by learning, that the MAC addresses come from the PW1, and also knows that the PW1and the PW2are in a primary/backup relationship, and that the PW1and the PW3are in a primary/backup relationship, but the PE3cannot distinguish which multihoming protection group the MAC address learned from the PW1belongs to. Therefore, when the PE1or the PW1fails, to ensure accessibility of data, the PE3sends the received data packet to the PW2and the PW3respectively according to the backup forwarding entry. In a case that the PW1and the PE1do not fail but the designated forwarder is switched in a certain multihoming protection group, for example, in the multihoming protection group formed by the PE1and the PE2, the designated forwarder is switched, and the PE2is switched to act as the designated forwarder, the PE3forwards, to the PW1and the PW2according to the backup forwarding entry, the data packet that is received through the CE2and whose destination address is the MAC address of the CE1or the CE3, or whose destination address is the MAC address of the customer device connected to the CE1or the CE3.

In the preceding case, the amount of data that the PE3needs to send increases to a certain extent, for example, the data destined to the CE3is sent to the PE2and the PE4respectively. However, compared with broadcasting to the whole VPLS, this still saves a lot of bandwidth resources and processing resources. In addition, the increase in the data amount may be avoided through proper networking planning, for example, multiple CEs belonging to the same VPLS may be dual-homed to a same group of PEs. Therefore, the VPLS fast rerouting method provided in the embodiment of the present invention can still achieve the effect of reducing an unnecessary waste of bandwidth resources and processing overhead, and avoiding an interruption of a service between CEs in the case that multiple multihoming protection groups have overlapped PEs.

According to the VPLS fast rerouting method provided in the embodiment of the present invention, a remote PE generates a backup forwarding entry; and when a designated forwarder or a designated forwarder pseudo wire in a multihoming protection group fails, or the designated forwarder is switched in the multihoming protection group, the remote PE forwards a data packet according to the backup forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to a same VPLS instance, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE. Further, MAC forwarding table information is synchronized between PEs that are in the multihoming protection group and connected to the remote PE, and local MAC forwarding entries are generated according to the MAC forwarding table information; and, when the designated forwarder or the designated forwarder pseudo wire in the multihoming protection group fails, or when the designated forwarder is switched in the multihoming protection group, the PE receiving a data packet in the multihoming protection group forwards the data packet by using its MAC forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to the same VPLS instance and all local interfaces, and avoiding a possible service interruption, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE.

As shown inFIG. 7, embodiment 2 of the present invention provides a VPLS fast rerouting device70, where the VPLS fast rerouting device70may exemplarily be a PE3. Embodiment 2 takes a PE3as the VPLS fast rerouting device70for description, where the PE3includes:

a MAC address information acquiring unit701, configured to acquire MAC address information from a data packet received through a pseudo wire PW1;

a multihoming protection group information acquiring unit702, configured to acquire information about a multihoming protection group formed by a PE1and a PE2, where the PE1and the PE2are connected to the PE3, the PE1is selected as a designated forwarder in the multihoming protection group, and the PE2acts as a non-designated forwarder;

a backup forwarding entry generating unit703, configured to generate a backup forwarding entry according to the source MAC address information acquired by the MAC address information acquiring unit701and the information about the multihoming protection group acquired by the multihoming protection group information acquiring unit702, where the source MAC address information in the backup forwarding entry is associated with a PW2, and the PE1and the PE2are connected to the PE3through the PW1and the PW2respectively; and

a packet forwarding unit704, configured to forward the packet by using the backup forwarding entry when the PW1fails, the PE1fails, or the designated forwarder is switched.

As further shown inFIG. 2, a PE1, a PE2, a PE3, a PE4, and a PE5, and a CE1, a CE2, and a CE3belong to a same VPLS. The CE1is dual-homed to access the PE1and the PE2through an AC1and an AC2respectively, and the PE1and the PE2are connected to the PE3through the PW1and the PW2respectively, where the PE1and the PE2form a multihoming protection group. Through a multihoming information advertisement mechanism or through a manual configuration, the multihoming protection group information acquiring unit702of the PE3may acquire information about the multihoming protection group formed by the PE1and the PE2, and thereby knows that the PE1and the PE2belong to the same multihoming protection group and they are dual-homed PEs of the CE1. In the multihoming protection group, one PE is selected as a designated forwarder, and the other PE is a non-designated forwarder. For example, if the PE1is selected as the designated forwarder, the PE2is the non-designated forwarder, and the AC2between the PE2and the CE1is in blocked state. The CE1sends a data packet destined to the CE2to the PE1through the AC1; the PE1sends the data packet to the PE3through the PW1according to a MAC forwarding entry; when the PE3receives the data packet from the CE1through the PW1, the MAC address information acquiring unit701learns a source MAC address from the received data packet, where the source MAC address may exemplarily be a MAC address of the CE1, and may also be a MAC address of a customer device (not illustrated in the figure) connected to the CE1; a primary forwarding entry generating unit of the PE3generates a primary forwarding entry according to the learned source MAC address, where the learned source MAC address in the primary forwarding entry is associated with the PW1and then is used to guide forwarding of the data packet whose destination MAC address is the CE1or whose destination MAC address is the customer device connected to the CE1; and the backup forwarding entry generating unit703binds the source MAC address learned from the data packet received through the PW1with the pseudo wire PW2to generate a backup forwarding entry.

For example, the MAC address information acquiring unit701of the PE3acquires a source MAC address HH-HH-HH-HH-HH-HH from the data packet received through the PW1, and the primary forwarding entry generating unit generates a primary forwarding entry according to the learned source MAC address, where the MAC address HH-HH-HH-HH-HH-HH in the primary forwarding entry is associated with the PW1; and the backup forwarding entry generating unit703concurrently generates a backup forwarding entry according to the learned source MAC address, where the HH-HH-HH-HH-HH-HH in the backup forwarding entry is associated with the PW2.

For example, the PE3may further include a failure detecting unit, where the failure detecting unit uses a detection mechanism, such as BFD and LSP-Ping, to detect failures of the PW1and the PE1, or receives a notification that the designated forwarder is switched in the multihoming protection group. When the failure detecting unit detects that the PW1or the PE1fails, or receives a notification that the designated forwarder is switched to the PE2and that is sent by the PE1or the PE2, the failure detecting unit does not wait for a process of relearning the MAC address, and the packet forwarding unit704directly sends, according to the backup forwarding entry, data by unicast through the PW2. For example, if, when the PE3receives from the CE2a data packet whose destination address is the MAC address of the CE1or whose destination address is the MAC address of the customer device connected to the CE1, the failure detecting unit detects that the PW1fails, detects that the PE1fails, or learns that the DF is switched to the PE2, the packet forwarding unit704queries the backup forwarding entry, finds that the MAC address of the CE1and the MAC address of the customer device connected to the CE1are bound with the PW2, and therefore, sends to the PW2the data packet whose destination address is the MAC address of the CE1or whose destination address is the MAC address of the customer device connected to the CE1, thereby avoiding broadcasting the data packet destined to the CE1to all provider edge devices PE1, PE2, PE4, and PE5that belong to the same VPLS, and further reducing an unnecessary waste of bandwidth resources in a backbone network and processing overhead.

The PE3disclosed in this embodiment may also be used in a network where a multihoming protection group includes multiple PEs. For example, in the network shown inFIG. 5, the multihoming protection group includes three PEs: a PE3, a PE4, and a PE5. A CE1accesses a PE1, a PE2, and the PE4through attachment circuits AC1, AC2, and AC3respectively. In the multihoming protection group, one PE thereof is selected as a designated forwarder, and other PEs are non-designated forwarders. For example, if the PE1is selected as a designated forwarder, the PE2and the PE4are non-designated forwarders, and the AC2between the PE2and the CE1and the AC3between the PE4and the CE1are in blocked state. The CE1sends a data packet destined to a CE2to the PE1through the AC1; the PE1sends the data packet to the remote PE3through a PW1according to a MAC forwarding entry; when the PE3receives the data packet from the CE1through the PW1, the MAC address information acquiring unit701of the PE3learns a source MAC address from the received data packet, where the source MAC address may exemplarily be a MAC address of the CE1, and may also be a MAC address of a customer device (not illustrated in the figure) connected to the CE1; a primary entry forwarding unit of the PE3generates a primary forwarding entry according to the learned source MAC address, where the learned source MAC address in the primary forwarding entry is associated with the PW1and then is used to guide forwarding of the data packet whose destination MAC address is the MAC address of the CE1or whose destination MAC address is the MAC address of the customer device connected to the CE1. In addition, the backup forwarding entry generating unit703of the PE3binds the source MAC address learned from the data packet received through the PW1with pseudo wires PW2and PW3to generate a backup forwarding entry. For example, a failure detecting unit included in the PE3may use a detection mechanism, such as BFD and LSP-Ping, to detect failures of the PW1and the PE1or receives from the PE1, PE2, or PE4a notification that the designated forwarder is switched. When the failure detecting unit detects that the PW1or PE1fails, or receives a notification that the designated forwarder is switched and that is sent by the PE1or the PE2, the PE3does not wait for a process of relearning the MAC address, and the packet forwarding unit704of the PE3directly sends, by using the backup forwarding entry, the data packet through the pseudo wires PW2and PW3that belong to the same multihoming protection group as the PW1. For example, the packet forwarding unit704in the PE3further includes a failure forwarding unit; if, when the PE3receives from the CE2a data packet whose destination address is the MAC address of the CE1or whose destination address is the MAC address of the customer device connected to the CE1, the failure detecting unit of the PE3detects that the PW1or the PE1fails but no notification that the designated forwarder is switched is received, the failure forwarding unit queries the backup forwarding entry, finds that the destination MAC address of the received data packet is bound with the PW2and the PW3, and therefore sends the data packet to the PW2and PW3respectively. The packet forwarding unit704in the PE3further includes a designated forwarder forwarding unit; if, when the PE3receives from the CE2a data packet whose destination address is the MAC address of the CE1or whose destination address is the MAC address of the customer device connected to the CE1, the failure detecting unit has received a notification that the designated forwarder is switched, for example, the designated forwarder is switched to the PE4, the designated forwarder forwarding unit directly sends the data packet to the PW3according to the backup forwarding entry. In the preceding two cases, broadcasting, by the PE3, the data packet destined to the CE1to all PEs that belong to the same VPLS can be avoided, and an unnecessary waste of bandwidth resources in a backbone network and processing overhead can be reduced.

According to the embodiment of the present invention, the VPLS fast rerouting device generates a backup forwarding entry; and when a designated forwarder or a designated forwarder pseudo wire in a multihoming protection group fails, or the designated forwarder is switched in the multihoming protection group, the VPLS fast rerouting device forwards a data packet according to the backup forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to the same VPLS instance, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE.

As shown inFIG. 8, embodiment 3 of the present invention provides a VPLS fast rerouting method, where the method includes the following:

801. A PE2in a multihoming protection group receives MAC forwarding table information on a PE1from the PE1, generates its MAC forwarding entry by replacing an identifier of a PW or an AC in the MAC forwarding table information with an identifier of a pseudo wire PW or an attachment circuit AC connected to the PE2, where both the PW and the AC connected to the PE2and the PW and the AC in the MAC forwarding table information belong to the multihoming protection group, and in the multihoming protection group, the PE1is selected as a designated forwarder, and the PE2is a non-designated forwarder.

802. When the PE1in the multihoming protection group fails, the PW in the MAC forwarding table information fails, or the PE2is switched to act as the designated forwarder, the PE2receiving a data packet forwards the data packet by using its MAC forwarding entry.

The VPLS fast rerouting method provided in embodiment 3 of the present invention is the same as the method for synchronizing MAC forwarding table information between PEs in a multihoming protection group, where the synchronization method is in the VPLS fast rerouting method provided in embodiment 1 of the present invention, and is not further described herein. Though this embodiment describes the method for synchronizing MAC forwarding table information between PEs by taking an example in which the VPLS multihoming protection group includes two PEs, same as the method for synchronizing MAC forwarding table information between multiple PEs in the multihoming protection group in embodiment 1, the VPLS fast rerouting method provided in embodiment 3 is also applicable to the case that a multihoming protection group includes multiple PEs, which is not further described herein.

According to the VPLS fast rerouting method provided in the embodiment of the present invention, MAC forwarding table information is synchronized between PEs in a multihoming protection group, and local MAC forwarding entries are generated according to the MAC forwarding table information; and when a designated forwarder or a designated forwarder pseudo wire in the multihoming protection group fails, or when the designated forwarder is switched in the multihoming protection group, the PE receiving a data packet forwards the data packet by using its MAC forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to a same VPLS instance and all local interfaces, and avoiding a possible service interruption, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE.

As shown inFIG. 9, embodiment 4 of the present invention further provides a VPLS fast rerouting device, where the VPLS fast rerouting device90may exemplarily be a PE2. Embodiment 4 takes a PE2as the VPLS fast rerouting device90for description, where the PE2includes:

a MAC forwarding table information receiving unit901, configured to receive MAC forwarding table information of a PE1sent by the PE1in a multihoming protection group;

a MAC forwarding entry generating unit902, configured to generate a MAC forwarding entry of the PE2itself by replacing identifiers of a PW and an AC that are in the MAC forwarding table information with identifiers of a pseudo wire and an AC that are connected to the PE2, where both the pseudo wire and the AC connected to the PE2and the PW and AC in the MAC forwarding table information belong to the multihoming protection group; and

a packet forwarding unit903, configured to forward a data packet according to the MAC forwarding entry of the PE2itself when the PE1fails, or a PW1fails, or the PE2is switched to act as a designated forwarder.

As further shown inFIG. 2, a PE1, a PE2, a PE3, a PE4, and a PE5, and a CE1, a CE2, and a CE3belong to a same VPLS. The CE1is dual-homed to access the PE1and the PE2through an AC1and an AC2respectively, and the PE1and the PE2are connected to the PE3through the PW1and a PW2respectively, where the PE1and the PE2form a multihoming protection group. In the multihoming protection group, one PE is selected as a designated forwarder, and the other PE is a non-designated forwarder. For example, if the PE1is selected as a designated forwarder, the PE2is a non-designated forwarder. Here the pseudo wire PW2between the PE2and the PE3may be referred to as a non-designated forwarder pseudo wire. For example, the PE1acting as the designated forwarder in the multihoming protection group may synchronize MAC forwarding table information learned from the AC1and that learned from the PW1to the PE2, where the synchronization may be implemented by extending an existing control protocol or by defining a new control protocol. The MAC forwarding table information receiving unit901included in the PE2receives the MAC forwarding table information synchronized from the PE1, and the MAC forwarding entry generating unit902generates the MAC forwarding entry of the PE2itself according to the MAC forwarding table information. For example, the MAC forwarding table information receiving unit901may include an Inter-Chassis Communications Protocol ICCP unit configured to receive an ICCP message sent by the PE1and acquire the MAC forwarding table information carried in an application specific type-length-value Application Specific TLV in a redundancy protection group application data message RG Application Data Message of the ICCP protocol; and the MAC forwarding entry generating unit902generates the MAC forwarding entry of the PE2itself by using the MAC forwarding table information acquired by the Inter-Chassis Communications Protocol ICCP unit. The MAC forwarding table information receiving unit901may further include a user-defined control protocol unit, configured to receive a new user-defined control protocol message that is sent by the PE1for synchronizing MAC forwarding table information between PE devices, and acquire MAC forwarding table information carried in the new user-defined control protocol message; and the MAC forwarding entry generating unit902generates the MAC forwarding entry of the PE2by using the MAC forwarding table information acquired by the Inter-Chassis Communications Protocol ICCP unit or the user-defined control protocol unit. The method for synchronizing MAC forwarding table information between the PE2and the PE1in this embodiment is the same as the method that is for synchronizing MAC forwarding table information between the PE1and the PE2in the multihoming protection group in the VPLS fast rerouting method and is in the VPLS fast rerouting method provided in embodiment 1 of the present invention, and is not further described herein.

For example, if, when the PE2receives data from the PW2, the designated forwarder has been switched to the PE2, the packet forwarding unit903directly forwards, by using a local forwarding entry generated according to the MAC forwarding table information synchronized from the PE1, data to the AC2by unicast: For a qualified learning Qualified learning mode, the packet forwarding unit903performs forwarding to the AC2that belongs to VLAN B of VPLS A, without broadcasting on all ACs that belong to VLAN B of VPLS A; and for an unqualified learning Unqualified learning mode, the packet forwarding unit903performs forwarding to the AC2that belongs to VPLS A, without broadcasting on all ACs that belong to VPLS A. After synchronization of MAC forwarding table information between the PE1and the PE2is completed, because a MAC forwarding table of the PE2includes a forwarding entry where a MAC address of the CE1is associated with the AC2and a forwarding entry where a MAC address of a customer device connected to the CE1is associated with the AC2, the packet forwarding unit903directly forwards, to the AC2by unicast according to a table lookup result of the MAC forwarding table, the data packet whose destination address is the MAC address of the CE1or that of the customer device connected to the CE1.

For customer data traffic sent from the CE1to the CE2, when the AC1, the PE1, or the PW1fails, the designated forwarder is switched to the PE2through synchronization of state information, and at this time, the CE1sends a data packet to the PE2by using the AC2. Though the PE2has not learned remote MAC address information through a data plane at this time, by using a mechanism that is for synchronizing MAC forwarding table information between the PE1and the PE2provided in this embodiment and where the MAC forwarding table of the PE2includes a forwarding entry that associates a MAC address of the remote CE2and a MAC address of a customer device connected to the CE2with the PW2, and the packet forwarding unit903in the PE2directly forwards, to the PW2by unicast according to the table lookup result of the MAC forwarding table, the data packet whose destination address is the MAC address of the CE2and the data packet whose destination address is the MAC address of the customer device connected to the CE2, thereby avoiding unnecessary data broadcasting in a backbone network.

Further, the PE2further includes a MAC forwarding table information sending unit, configured to synchronize, by the PE2, its MAC forwarding table information to the PE1in the multihoming protection group after being switched to act as the designated forwarder, so that, when the PE2fails, or PW2fails, or the PE1is switched again to act as the designated forwarder, the PE1may forward a received data packet by using its forwarding entry generated according to the MAC forwarding table information.

Though this embodiment describes the VPLS fast rerouting device provided in embodiment 4 by taking an example where a VPLS multihoming protection group includes two PEs, the VPLS fast rerouting device provided in embodiment 4 of the present invention is also applicable to the case that the multihoming protection group includes multiple PEs, which is not further described herein.

When MAC forwarding table information sent by a designated forwarder PE in a multihoming protection group is received, the VPLS fast rerouting device provided in the embodiment of the present invention generates its MAC forwarding entry according to the MAC forwarding table information; and, when the designated forwarder or a designated forwarder pseudo wire in the multihoming protection group fails, or when the VPLS fast rerouting device is switched to act as the designated forwarder, the VPLS fast rerouting device receiving a data packet forwards the data packet by using its MAC forwarding entry, thereby avoiding broadcasting the data packet to all remote PEs that belong to a same VPLS instance and all local interfaces, and avoiding a possible service interruption, and further reducing a waste of bandwidth resources in a backbone network and processing resources of the PE.

According to description of the preceding implementation manners, a person of ordinary skill in the art may clearly understand that the embodiments of the present invention may be implemented through software plus a necessary universal hardware platform, and may certainly be implemented through hardware. Based on such an understanding, technical solutions in the embodiments of the present invention may find an expression in a form of a software product, and the computer software product may be stored in a storage medium, such as an ROM/RAM, a magnetic disk, or an optical disk, and include several instructions that enables a computer device, a server, or another network device to execute the methods described in the embodiments of the present invention or in some parts of the embodiments of the present invention.

The foregoing descriptions are merely exemplary embodiments of the present invention, but not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, and so on made without departing from the spirit and principle of the present invention shall fall within the protection scope of the present invention.