CN114531396B

CN114531396B - Fault back switching method and device in Ethernet virtual private network

Info

Publication number: CN114531396B
Application number: CN202011197017.2A
Authority: CN
Inventors: 詹兰兰
Original assignee: Beijing Huawei Digital Technologies Co Ltd
Current assignee: Beijing Huawei Digital Technologies Co Ltd
Priority date: 2020-10-31
Filing date: 2020-10-31
Publication date: 2024-01-16
Anticipated expiration: 2040-10-31
Also published as: CN114531396A

Abstract

A method and apparatus for fast convergence unicast routing in an Ethernet virtual private network. The method comprises the following steps: the CE is connected to the first PE and the second PE, and the first PE and the second PE work in a single-active mode, when the first PE is switched to a non DF by a DF corresponding to the CE, the first PE updates the MAC routing information of the CE and indicates the corresponding low priority, so that the remote PE can select a proper forwarding path for a message sent to the CE according to the priority of each MAC routing information of the CE, thereby optimizing the unicast routing of the CE, enabling the unicast routing to be converged to the current DF rapidly, effectively shortening the forwarding time of the message and avoiding the bypass time of the message in the network.

Description

Fault back switching method and device in Ethernet virtual private network

Technical Field

The present disclosure relates to the field of communications technologies, and in particular, to a method and an apparatus for fault back switching in an ethernet virtual private network.

Background

In the prior art, an ethernet virtual private network (ethernet virtual private network, EVPN) can operate in a dual-homing single-active scenario as shown in fig. 1. The dual-homing single-activity scenario refers to that the user edge device (customer edge equipment, CE) 1 accesses the operator edge devices (provider edge router, PE) 1 and PE2, but the PE1 and PE2 operate in a single-activity mode or a single-redundancy mode, i.e. at the same time, only one PE of the PE1 and PE2 is responsible for forwarding the message of the CE 1. The PE responsible for forwarding the message of CE1 may be referred to as designated forwarder (designated forwarder, DF) at this time, and the PE not responsible for forwarding the message of CE1 may be referred to as non-designated forwarder (non designated forwarder, non DF).

In the dual homing single-shot scenario shown in fig. 1, it is assumed that in the normal state, PE1 is DF of CE1 and PE2 is non DF of CE1. If the link between CE1 and PE1 fails, PE1 will switch to the non DF for CE1 and PE2 will switch to the DF for CE1, a process known as the tangent to failure process. In the fault tangent process, as shown in fig. 2, in order to reduce packet loss, in one aspect, PE1 may re-establish a fast reroute (FRR) link with PE2 based on a media access control (media access control, MAC), and send a received downlink packet of CE1 from PE3 to PE2 through the MAC FRR link, and then the PE2 sends the downlink packet of CE1 to CE1. On the other hand, PE1 may not withdraw the MAC route of CE1, but wait for its aging, so that PE3 may maintain unicast to PE1 before the MAC route of CE1 ages, and then switch unicast to PE2 according to the fast convergence mechanism.

When the link between CE1 and PE1 is restored, PE1 may be switched again to the DF of CE1 and PE2 may be switched again to the non-DF of CE1, a process known as a fail-back process. In the failure back-off procedure, as shown in fig. 3, in order to avoid broadcast flooding, PE2 may not withdraw the MAC route of CE1, but wait for its aging. Thus, before PE1 receives the uplink message from CE1, the downlink message from CE1 of PE3 can continue unicast to PE2, and after bypassing to PE1 via MAC FRR link, the downlink message is finally sent to CE1. However, before the MAC route of the CE1 corresponding to the PE2 is aged, if the CE1 has already switched the upstream traffic back to the PE1, because the ethernet segment identifiers (ethernet segment identifier, ESI) of the PE1 and the PE2 are the same, it cannot be guaranteed that the unicast traffic of the PE3 is switched to the PE1, which results in too long bypass time.

Disclosure of Invention

The method and the device for switching back faults in the Ethernet virtual private network are used for optimizing unicast routes in the flow switching back process under the double-return single-activity scene and improving the flow path switching efficiency.

In a first aspect, the present application provides a method for fault-back in an ethernet virtual private network, where the method may be performed by a first PE, or may be performed by a component (e.g., a chip or a circuit) configured in the first PE. The method comprises the following steps: the first PE determines that DF corresponding to CE is switched to non DF, the CE is connected to the first PE and the second PE, and the first PE and the second PE work in a single-active mode; the first PE sends a first route notification message to the far-end PE, wherein the first route notification message is used for notifying first MAC route information of the CE, and the priority of the first MAC route information is lower than a preset priority.

By adopting the technical scheme, when a certain PE accessed by a CE is switched to a non DF by the DF corresponding to the CE, the PE updates the MAC routing information of the CE and indicates the corresponding low priority, so that the remote PE can select a proper forwarding path for a message sent to the CE according to the priority of each MAC routing information of the CE, thereby optimizing the unicast routing of the CE, enabling the unicast routing to be converged to the current DF rapidly, effectively shortening the forwarding time of the message and avoiding the bypass time of the message in a network.

In one possible design, if the remote PE is an IBGP neighbor of the first PE, the priority of the first MAC routing information may be indicated by a local_pref attribute of the first MAC routing information; as such, the priority of the first MAC routing information being lower than the preset priority may mean that: the attribute value of the local_pref attribute in the first MAC routing information is smaller than the attribute value of the local_pref attribute corresponding to the preset priority.

In one possible design, if the remote PE is an EBGP neighbor of the first PE, the priority of the first MAC routing information may be indicated by an MED attribute of the first MAC routing information; as such, the priority of the first MAC routing information being lower than the preset priority may mean that: the attribute value of the MED attribute of the first MAC routing information is larger than the attribute value of the MED attribute corresponding to the preset priority.

In a second aspect, the present application provides another method of failover in an ethernet virtual private network, which may be performed by a remote PE, or by a component (e.g., a chip or circuit) configured at the remote PE. The method comprises the following steps: the remote PE receives a route notification message from a second PE, wherein the route notification message is used for notifying second MAC route information of a CE, the CE is accessed to the first PE and the second PE, and the first PE and the second PE work in a single-active mode; if the second MAC routing information is the last received MAC routing information of the CE, the remote PE determines to forward the message of the CE through the second PE according to the second MAC routing information.

By adopting the technical scheme, in the fault back switching process, when the second PE is switched to DF from non DF corresponding to CE and the second MAC route information of the CE is correspondingly announced, the unicast route from the remote PE to the CE can be quickly converged to DF corresponding to the CE at the moment by setting the route selection principle of the remote PE to take the last updated MAC route information as priority, thereby effectively shortening the forwarding time of the message and avoiding the overlong detour time of the message in the network.

In a third aspect, the present application provides a fault back-switching device, where the device has a function of implementing the first PE in the above aspects, or has a function of implementing the remote PE in the above aspects, and the device may be an operator edge device, or may be a chip included in the operator edge device.

The functions of the above apparatus may be implemented by hardware, or by executing corresponding software by hardware, or by a combination of hardware and software, where the hardware or software includes one or more modules or units or means (means) corresponding to the functions described above.

In one possible design, the apparatus includes a processing module and a transceiver module in a structure of the apparatus, where the processing module is configured to support the apparatus to perform a function corresponding to the first PE in the above aspects, or perform a function corresponding to the remote PE in the above aspects. The transceiver module is configured to support communication between the apparatus and other communication devices, for example, when the apparatus is the first PE, the routing update message may be sent to the remote PE. The apparatus may also include a memory module coupled to the processing module that holds the program instructions and data necessary for the apparatus. As an example, the processing module may be a processor, the communication module may be a transceiver, and the storage module may be a memory, where the memory may be integrated with the processor or may be separately provided from the processor.

In another possible design, the device may include a processor and may also include a memory. The processor is coupled to the memory and is operable to execute the computer program instructions stored in the memory to cause the apparatus to perform the methods of the above aspects. Optionally, the apparatus further comprises a communication interface, the processor being coupled to the communication interface. When the device is a first PE or a remote PE, the communication interface may be a transceiver or an input/output interface; when the device is a chip contained in the first PE or a chip contained in the remote PE, the communication interface may be an input/output interface of the chip. Alternatively, the transceiver may be a transceiver circuit and the input/output interface may be an input/output circuit.

In a fourth aspect, embodiments of the present application provide a chip system, including: a processor coupled to a memory for storing programs or instructions which, when executed by the processor, cause the system-on-a-chip to implement the methods of the above aspects.

Optionally, the system on a chip further comprises an interface circuit for interacting code instructions to the processor.

Alternatively, the processor in the chip system may be one or more, and the processor may be implemented by hardware or software. When implemented in hardware, the processor may be a logic circuit, an integrated circuit, or the like. When implemented in software, the processor may be a general purpose processor, implemented by reading software code stored in a memory.

Alternatively, the memory in the system-on-chip may be one or more. The memory may be integral to the processor or separate from the processor. For example, the memory may be a non-transitory processor, such as a read only memory ROM, which may be integrated on the same chip as the processor or may be separately provided on different chips.

In a fifth aspect, embodiments of the present application provide a computer-readable storage medium having stored thereon a computer program or instructions which, when executed, cause a method in any one of the above aspects or any one of the possible designs of the aspects to be implemented.

In a sixth aspect, embodiments of the present application provide a computer program product which, when executed by a communications apparatus, causes the method in any one of the above aspects or any one of the possible designs of the aspects to be implemented.

In a seventh aspect, embodiments of the present application provide a communication system including a CE, a first PE, and a second PE. Optionally, the communication system may further include a remote PE. Optionally, a remote CE may be included in the communication system.

Drawings

Fig. 1 and 2 are schematic diagrams of a fault tangent process in an EVPN network in the prior art;

fig. 3 is a schematic diagram of a fault loop-back procedure in an EVPN network in the prior art;

fig. 4 is a flow chart of a fault back-switching method in an EVPN network according to an embodiment of the present application;

fig. 5 is a schematic diagram of a first PE switched to a non DF in the embodiment of the present application guiding a remote PE to select a packet forwarding path by reducing the priority of MAC routing information;

FIGS. 6a and 6b are diagrams illustrating an example of a message structure and an attribute structure according to an embodiment of the present application;

fig. 7 is a flowchart of another fault back-switching method in an EVPN network according to an embodiment of the present application;

fig. 8 is a schematic diagram of a remote PE selecting a packet forwarding path according to last received MAC routing information in the embodiment of the present application;

fig. 9 is a schematic structural diagram of a communication device according to an embodiment of the present application;

fig. 10 is another schematic structural diagram of a communication device according to an embodiment of the present application.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present application more apparent, the embodiments of the present application will be described in further detail with reference to the accompanying drawings.

It should be noted that the terms "system" and "network" in the embodiments of the present application may be used interchangeably. The term "plurality" means two or more, and in view of this, the term "plurality" may also be understood as "at least two" in the embodiments of the present application. "at least one" may be understood as one or more, for example as one, two or more. For example, including at least one means including one, two or more, and not limiting what is included. For example, at least one of A, B and C is included, then A, B, C, A and B, A and C, B and C, or A and B and C may be included. Likewise, the understanding of the description of "at least one" and the like is similar. "and/or", describes an association relationship of an association object, and indicates that there may be three relationships, for example, a and/or B, and may indicate: a exists alone, A and B exist together, and B exists alone. The character "/", unless otherwise specified, generally indicates that the associated object is an "or" relationship.

Unless stated to the contrary, the embodiments of the present application refer to ordinal terms such as "first," "second," etc., for distinguishing between multiple objects, and are not intended to limit the order, timing, priority, or importance of the multiple objects, nor are the descriptions of "first," "second," etc., to limit the objects to be different.

Fig. 4 is a schematic flow chart of a fault back-switching method in an EVPN network according to an embodiment of the present application. The method comprises the following steps:

in step S401, the first PE determines that the designated forwarder DF corresponding to the CE is switched to the non-designated forwarder non DF.

In the embodiment of the application, the CE accesses the first PE and the second PE.

In one possible implementation, the CE may dual-home to the first PE and the second PE. The dual homing access of the CE to the first PE and the second PE may also be referred to as dual homing of the CE to the first PE and the second PE, or dual homing of the CE to the first PE and the second PE means that the CE is connected to both the first PE and the second PE, and the first PE or the second PE may forward a message from or sent to the CE.

The first PE and the second PE operate in a single active mode, which may also be referred to as a single redundant mode or have other names, and is not limited. The single-active mode specifically means that at the same time, only one PE of the first PE and the second PE is used as the DF corresponding to the CE to be responsible for forwarding the message of the CE, while the other PE is used as the non DF corresponding to the CE to be not responsible for forwarding the message of the CE. Thus, if a first PE is switched from a DF corresponding to that CE to a non-DF, this means that the second PE will switch the corresponding non-DF corresponding to that CE to a DF.

Alternatively, the second PE may be the default or preferred PE selected as DF from the two PEs of the CE dual homing access, or the PE that has been previously selected as DF according to some preset election rule. Thus, in the case that the communication link between the CE and the second PE is normal, the second PE will serve as the DF corresponding to the CE and be responsible for forwarding the message of the CE. If the communication link between the CE and the second PE is faulty, the second PE and the first PE can perform fault tangent processing accordingly, so that the second PE is switched to the non DF by the DF corresponding to the CE, and the first PE is switched to the DF by the non DF corresponding to the CE. After the communication link between the CE and the second PE is restored, the second PE and the first PE may perform a fault back-switching process, so that the second PE is switched back to the DF by the non-DF corresponding to the CE, and the first PE is switched back to the non-DF by the DF corresponding to the CE.

In another possible implementation, the CE may also access more other PEs in a multi-homing manner, which is not limited in this application. If the CE accesses more other PEs in a multi-homing manner, the second PE may refer to a PE that is default or preferred to be selected as DF from among the PEs to which the CE multi-homing accesses, or a PE that has been previously selected as DF according to some preset rule. The first PE may refer to a PE elected as a DF corresponding to the CE after a failure of a communication link between the CE and the second PE. It can be understood that in this case, after the communication link between the CE and the second PE is restored, the second PE may be switched to the DF corresponding to the CE again through the fault back-switching process, and accordingly, the first PE may be switched to the non DF corresponding to the CE again. While other PEs may always exist as non DF corresponding to that CE during the process.

The technical scheme of the embodiment of the application is specifically described below by taking CE dual homing access to a first PE and a second PE as an example.

In step S402, the first PE sends a first routing advertisement packet to the remote PE, where the first routing advertisement packet is used to advertise first MAC routing information of the CE, and a priority of the first MAC routing information is lower than a preset priority.

Accordingly, the remote PE may receive the first route advertisement message from the first PE.

In this embodiment of the present application, the remote PE is a PE to which a remote CE that communicates with the CE accesses. The remote CE may access one PE, or multiple PEs in a multi-homing manner, which is not limited in this application. If a remote CE accesses multiple PEs in a multi-homing manner, the remote PE may refer to the DF among the multiple PEs accessed by the remote CE. By sending the first route notification message to the PE serving as the DF in the multiple PEs accessed by the remote CE, the PE serving as the DF can select a proper forwarding path for the message from the remote CE and sent to the CE according to the first MAC routing information of the CE in the first route notification message. Optionally, the first PE may send the first routing advertisement packet to all the PEs accessed by the remote CE, or the first PE may also send the first routing advertisement packet to a non DF in the PEs accessed by the remote CE, so that the PEs serving as the non DF may record the first MAC routing information, update, according to the first MAC routing information, a routing table entry corresponding to the CE in the own routing forwarding table, so that after the non DF is switched to the DF, the corresponding processing may be performed according to the first MAC routing information.

For example, as shown in fig. 5, after the first PE is switched from the DF corresponding to the CE to the non-DF, the first PE may send a first routing advertisement packet to the remote PE, update the MAC routing information of the CE passing through the first PE to the first MAC routing information through the first routing advertisement packet, and indicate the priority of the first MAC routing information, where the priority of the first MAC routing information is lower than the preset priority.

Optionally, after the second PE is switched from the non DF corresponding to the CE to the DF, if the second PE receives an uplink packet from the CE, the second PE may send a second route notification packet to the remote PE, notify, by using the second route notification packet, second MAC routing information of the CE passing through the second PE, and indicate a priority of the second MAC routing information, where the priority of the second MAC routing information is greater than or equal to a preset priority.

It should be noted that the first route advertisement message and the second route advertisement message may have other names, and the application is not limited thereto, for example, the two messages may be referred to as a route update message and a route advertisement message, respectively, so that the first PE has already advertised the MAC route information of the CE through the first PE once when the CE is switched from the non DF of the CE to the DF. Alternatively, the two messages may be the same type of message, such as a MAC route advertisement message. The preset priority may also be called a default priority, a normal priority, or the like, and is not limited.

In other words, in the failure back-cut process, the first PE may advertise the MAC routing information of the CE via the first PE once (for clarity of description, referred to herein as the first MAC routing information) in the EVPN network after the DF corresponding to the CE is switched to the non-DF, and indicate that the first MAC routing information is of low priority. Optionally, after the second PE switches from the non DF corresponding to the CE to the DF, if an uplink packet from the CE is received, the second PE may also notify, in the EVPN network, the MAC routing information of the CE passing through the second PE once (for clarity of description, this will be referred to as second MAC routing information herein), and indicate that the second MAC routing information is of a preset priority (may also be referred to as default priority, normal priority, etc.) or high priority.

Furthermore, the remote PE may select a suitable path for forwarding a message from the remote CE and sent to the CE according to the priority of each received MAC routing information of the CE, where the message specifically refers to a unicast message from the remote CE to the CE, and optionally may be a unicast data message. Specifically, after receiving the first MAC routing information from the first PE, the remote PE may forward, based on the first MAC routing information, a message from the remote CE to the first PE before receiving the second MAC routing information from the second PE (i.e., before the second PE receives an uplink message from the CE and triggers a MAC routing advertisement), because only the first MAC routing information is available to direct the CE. Because the first PE is switched to the non DF corresponding to the CE at this time, the first PE can forward the message to the second PE through the MAC FRR link, and the second PE forwards the message to the CE. That is, in this case, the forwarding path of the unicast packet from the remote CE to the CE is { remote CE- > remote PE- > first PE- > second PE- > CE }, and the forwarding path needs to bypass the MAC FRR link between the first PE and the second PE.

After receiving the first MAC routing information from the first PE, the remote PE receives the second MAC routing information from the second PE (i.e. after the second PE receives the upstream message from the CE and triggers the MAC routing advertisement), and because both routes of the first MAC routing information and the second MAC routing information directed to the CE are reachable at this time, the priority of the first MAC routing information is smaller than that of the second MAC routing information, so that the remote PE may forward the message from the remote CE and sent to the CE to the second PE according to the second MAC routing information based on the principle that the priority of the MAC routing information is higher, and the second PE forwards the message to the CE. That is, in this case, the packet from the remote CE to the CE preferentially adopts a forwarding path { remote CE- > remote PE- > second PE- > the CE }, and the forwarding path does not need to bypass the MAC FRR link between the first PE and the second PE, so that the bypass time of the packet can be effectively shortened. The forwarding path originally via the first PE may be regarded as an alternative forwarding path in this case.

By adopting the technical scheme, when a certain PE accessed by a CE is switched to a non DF by the DF corresponding to the CE, the PE updates the MAC routing information of the CE and indicates the corresponding low priority, so that the remote PE can select a proper forwarding path for a message sent to the CE according to the priority of each MAC routing information of the CE, thereby optimizing the unicast routing of the CE, enabling the unicast routing to converge to the current DF more quickly, and effectively shortening the forwarding time of the message.

In this embodiment of the present application, the priority of the MAC routing information advertised by the first routing advertisement packet or the second routing advertisement packet may be indicated in various manners. Illustratively, taking the first MAC routing information as an example, in one possible implementation, if the remote PE is an internal border gateway protocol (internal border gateway protocol, IBGP) neighbor of the first PE, the priority of the first MAC routing information may be indicated by a local_priority (local_pref) attribute of the first MAC routing information.

The protocol specifies that the local_pref attribute in the border gateway protocol (border gateway protocol, BGP) route is a recognized attribute. This attribute must be included when a router updates the route to its own IBGP neighbors, which is a known mandatory attribute. The router may calculate the priority of each external route based on a locally configured policy and indicate the corresponding priority of each external route by means of a local_pref attribute when advertising the external route to its IBGP neighbor. The larger the attribute value of the local_pref attribute, the higher the priority of the corresponding MAC route, and the smaller the attribute value, the lower the priority of the corresponding MAC route. The attribute value of the local_pref attribute may be represented by a 4-byte unsigned integer, for example.

Therefore, the priority of the first MAC routing information being lower than the preset priority may mean that the attribute value of the local_pref attribute of the first MAC routing information is smaller than the attribute value of the local_pref attribute corresponding to the preset priority.

Similarly, if the remote PE is an IBGP neighbor of the second PE, the priority of the second MAC routing information may also be indicated by the local_pref attribute of the second MAC routing information. Therefore, the attribute value of the second MAC routing information being greater than or equal to the preset priority may mean that the attribute value of the local_pref attribute of the second MAC routing information is greater than or equal to the attribute value of the local_pref attribute corresponding to the preset priority. It will be appreciated that since the first PE and the second PE are two PEs connected to the same CE, both belonging to the same autonomous system (autonomous system, AS), when the far-end PE is an IBGP neighbor of the first PE, the far-end PE is also an IBGP neighbor of the second PE.

Optionally, the attribute value of the local_pref attribute corresponding to the preset priority may be a default attribute value of the local_pref attribute. Illustratively, the default attribute value of the local_pref attribute may be 100.

The protocol also specifies that the LOCAL router should also use the priority of the route indicated by the local_pref attribute for routing computation, and that high priority routes should be preferentially selected. Therefore, by adopting the above technical scheme, when the first PE is switched from the DF of the CE to the non-DF, for IBGP neighbors, the first PE may update the first MAC routing information, and reduce the priority of the first MAC routing information by modifying the attribute value of the local_pref attribute of the first MAC routing information, so as to instruct the far-end PE to select a suitable packet forwarding path according to the priority of the route.

For example, assuming that the default attribute value of the local_pref attribute is 100, when the first PE is switched from the DF of the CE to the non-DF, the first PE may advertise the first MAC routing information of the CE, and set the attribute value of the local_pref attribute of the first MAC routing information to be smaller than the default attribute value of the local_pref attribute, for example, may be set to 50, which indicates that the priority of the first MAC routing information is low priority, and the packet forwarding path indicated by the first MAC routing information to reach the CE via the first PE is an alternative path. When the second PE is switched to DF by the non DF of the CE, and receives an uplink packet from the CE, the second PE may also advertise second MAC routing information of the CE, and set an attribute value of a local_pref attribute of the second MAC routing information equal to a default attribute value of the local_pref attribute, for example, may be set to 100, which indicates that the priority of the first MAC routing information is normal priority or default priority or high priority, and a packet forwarding path indicated by the second MAC routing information to reach the CE via the second PE is a main path (or may also be referred to as a default path, a preferred path, etc.). Thus, after the remote PE receives the first MAC routing information from the first PE and the second MAC routing information from the second PE, the path selection may be performed on the packet sent to the CE according to the first MAC routing information and the second MAC routing information, and the packet forwarding path indicated by the second MAC routing information with higher priority is preferentially adopted, so that the packet is sent to the second PE, that is, the current DF.

In another possible implementation, if the remote PE is an external border gateway protocol (external border gateway protocol, EBGP) neighbor of the first PE, the priority of the first MAC routing information may be indicated by a multi-exit identification (multi-exit discriminator, MED) attribute of the first MAC routing information. The multi-outlet identification attribute may also be referred to as a multi-outlet authentication attribute.

The protocol specifies that the MED attribute in BGP routes is an optional non-transitive attribute used between different ases that is used to distinguish between different egress or ingress points when multiple links exist to the same AS. For a router, if a route with MED attributes is received from an EBGP neighbor, the attributes may be passed to all IBGP neighbors within the present AS. But the MED attribute transferred from one EBGP neighbor must not be transferred on to another EBGP neighbor of its own. The router may modify the MED value of a route learned from EBGP neighbors by local configuration, but it should be noted that if the MED value of a route learned from EBGP neighbors is modified by configuration on a router, such modification must be done before the priority of the route is determined and the route is selected.

The attribute value of the MED attribute may be referred to as a metric (or cost), and the attribute value of the MED attribute may be represented by an unsigned integer of 4 bytes, for example. For a router, when other conditions are the same, a route with smaller metric should be prioritized, i.e. the smaller the attribute value of the MED attribute, the higher the priority of the corresponding route, the larger the attribute value, and the lower the priority of the corresponding route.

Therefore, the priority of the first MAC routing information being lower than the preset priority may mean that the attribute value of the MED attribute of the first MAC routing information is greater than the attribute value of the MED attribute corresponding to the preset priority.

Similarly, if the remote PE is an EBGP neighbor of the second PE, the priority of the second MAC routing information may also be indicated by the MED attribute of the second MAC routing information. Therefore, the priority of the second MAC routing information being greater than or equal to the preset priority means that the attribute value of the MED attribute of the second MAC routing information is less than or equal to the attribute value of the MED attribute corresponding to the preset priority. It can be appreciated that, since the first PE and the second PE are two PEs connected to the same CE, and both belong to the same AS, when the far-end PE is an EBGP neighbor of the first PE, the far-end PE is also an IBGP neighbor of the second PE.

Optionally, the attribute value of the MED attribute corresponding to the preset priority may be a default attribute value of the MED attribute. Illustratively, the default attribute value of the MED attribute may be 0.

Therefore, by adopting the technical scheme, when the first PE is switched from DF of the CE to non DF, for the EBGP neighbor, the first PE can update the first MAC routing information, and the priority of the first MAC routing information is reduced by modifying the attribute value of the MED attribute of the first MAC routing information, so that the far-end PE is guided to select a proper message forwarding path according to the priority of the route.

For example, assuming that the default attribute value of the MED attribute is 0, when the first PE is switched from the DF of the CE to the non-DF, the first PE may advertise the first MAC routing information of the CE, and set the attribute value of the MED attribute of the first MAC routing information to be greater than the default attribute value of the MED attribute, for example, may be set to 50, indicating that the priority of the first MAC routing information is low, and the packet forwarding path indicated by the first MAC routing information to reach the CE via the first PE is an alternative path. When the second PE is switched to DF by the non DF of the CE, and receives an uplink packet from the CE, the second PE may also advertise second MAC routing information of the CE, and set an attribute value of the MED attribute of the second MAC routing information equal to a default attribute value of the MED attribute, for example, may be set to 0, to indicate that the priority of the first MAC routing information is a normal priority or a default priority or a high priority, and a packet forwarding path indicated by the second MAC routing information to reach the CE via the second PE is a main path (or may also be referred to as a default path, a preferred path, or the like). Thus, after the remote PE receives the first MAC routing information from the first PE and the second MAC routing information from the second PE, the path selection may be performed on the packet sent to the CE according to the first MAC routing information and the second MAC routing information, and the packet forwarding path indicated by the second MAC routing information with higher priority is preferentially adopted, so that the packet is sent to the second PE, that is, the current DF.

As an example, the route advertisement packet (such as the first route advertisement packet and the second route advertisement packet) in the embodiment of the present application may use a packet structure as shown in fig. 6a, where the packet structure includes the following fields: the length of the route to be withdrawn (withdrawn routes length), the route to be withdrawn (costs), the total length of the path attribute (total path attribute length), the path attribute value (path attributes), the network layer reachability information (network layer reachability information). Illustratively, the length of each field may be: the withdrawn route is 2 bytes long, the route to be withdrawn is variable (variable), the total length of the path attribute is 2 bytes long, the path attribute value is variable, and the network layer reachability information is variable.

The path attribute value of the message structure may include several routing attributes (or simply referred to as attributes), and each attribute structure may include an attribute flag (attr. Flags) and an attribute type Code (attr. Type Code) as shown in fig. 6 b. Both the local_pref attribute and the MED attribute referred to in this application may be located in a field of the path attribute value, the attribute type code of the local_pref attribute is 5, and the attribute type code of the MED attribute is 4.

Fig. 7 is a schematic flow chart of a fault back-switching method in an EVPN network according to another embodiment of the present application. The method comprises the following steps:

in step S701, the remote PE receives a route advertisement packet from the second PE, where the route advertisement packet is used to advertise second MAC route information of the CE.

In this embodiment of the present application, the CE accesses a first PE and a second PE. In one possible implementation, the CE may double-home to the first PE and the second PE, and the first PE and the second PE operate in a single-active mode. In another possible implementation manner, the CE may also access the first PE, the second PE and more other PEs in a multi-homing manner, which is not limited, and the multiple PEs in which the CE is multi-homing access still operate in a single active mode. For a description of the access manner of the CE, please refer to the related description above, and the description is not repeated.

The embodiment is also applied to a fault back-cut scenario, wherein a first PE refers to a PE switched from a DF corresponding to the CE to a non-DF in the fault back-cut process, a second PE refers to a PE switched from a non-DF corresponding to the CE to a DF in the fault back-cut process, and a far-end PE refers to a PE accessed by a far-end CE communicating with the CE or a DF in a plurality of accessed PEs. For the description of the first PE, the second PE and the remote PE, please refer to the related description above, and will not be repeated.

It should be noted that, when the first PE is switched from the DF corresponding to the CE to the non DF, the first PE may not cancel the first MAC routing information of the CE via the first PE, i.e., the first PE may not send a route cancellation message to the remote PE to cancel the first MAC routing information. When the second PE receives the uplink message from the CE after the second PE is switched from the non DF corresponding to the CE to DF, the second PE is triggered to notify the remote PE of the second MAC routing information of the CE via the second PE, i.e. the second PE sends a routing notification message to the remote PE to notify the second MAC routing information.

In step S702, if the second MAC routing information is the MAC routing information of the CE received by the remote PE last time, the remote PE determines, according to the second MAC routing information, to forward the message of the CE through the second PE.

For example, as shown in fig. 8, after the remote PE receives the second MAC routing information from the second PE, since the second MAC routing information is the last MAC routing information of the CE received by the remote PE, when the remote PE needs to forward the message from the remote CE and sent to the CE, the remote PE may forward the message to the second PE according to the second MAC routing information according to the principle that the last updated MAC routing information is based on the last updated MAC routing information. The message refers to a unicast message sent by a remote CE to the CE, and optionally, the message may be a unicast data message. By adopting the technical scheme, the routing principle of the remote PE is set to take the last updated MAC routing information as the priority, and the unicast route from the remote CE to the CE can be quickly converged to the DF corresponding to the CE at the moment, so that the forwarding time of the message is effectively shortened, and the message is prevented from bypassing too long in the network.

This may also be understood that, in the case that the first PE does not revoke the first MAC routing information of the CE, the far-end PE receives the second MAC routing information from the second PE again, and since the first MAC routing information and the second MAC routing information both point to the CE and the ethernet segment identifiers (ethernet segment identifier, ESI) of the two are the same, at this time, the far-end PE may determine, based on the last MAC routing information that can be received, that the forwarding path corresponding to the second MAC routing information is a primary forwarding path (or a preferred forwarding path), and that the forwarding path corresponding to the first MAC routing information is a secondary forwarding path (or an alternative forwarding path).

It can be seen that the method shown in fig. 7 is different from the method shown in fig. 4 in that, in the manner shown in fig. 7, the remote PE uses the latest received MAC routing information as a basis for the packet forwarding path, instead of determining the packet forwarding path according to the priority of the route.

The embodiment of the present application further provides a fault back-switching device, please refer to fig. 9, which is a schematic structural diagram of the fault back-switching device provided in the embodiment of the present application, where the fault back-switching device 900 includes: a transceiver module 910 and a processing module 920.

The fault back-cut device may be used to implement any of the method embodiments described above in relation to the first PE or the remote PE. For example, the device may be a chip or circuit included in a PE or router.

Illustratively, when the fault resilient means performs the operation or step corresponding to the first PE in the method embodiment shown in fig. 4, the processing module 920 is configured to determine that the DF corresponding to the CE is switched to the non DF, where the CE accesses the first PE and the second PE, and the first PE and the second PE operate in the single active mode; the transceiver module 910 is configured to send a first routing advertisement packet to a remote PE, where the first routing advertisement packet is used to advertise first MAC routing information of the CE, and a priority of the first MAC routing information is lower than a preset priority.

When the fault resilient switching device performs the operation or step of the corresponding remote PE in the method embodiment shown in fig. 7, the transceiver module 910 is configured to receive a route advertisement packet from a second PE, where the route advertisement packet is used to advertise second MAC route information of a CE, where the CE accesses the first PE and the second PE, and the first PE and the second PE operate in a single active mode; the processing module 920 is configured to determine, if the second MAC routing information is the MAC routing information of the CE received by the device last time, that the remote PE forwards the message of the CE through the second PE according to the second MAC routing information.

The processing module 920 involved in the fault resilient means may be implemented by at least one processor or processor-related circuit component and the transceiver module 910 may be implemented by at least one transceiver or transceiver-related circuit component or communication interface. The operations and/or functions of the respective modules in the communication device are not described herein for brevity to implement the respective flows of the methods shown in fig. 4, 5, 7, and 8. Optionally, the fault back-switching device may further include a storage module, where the storage module may be configured to store data and/or instructions, and the transceiver module 910 and/or the processing module 920 may read the data and/or instructions in the access module, so that the fault back-switching device implements a corresponding method. The memory module may be implemented, for example, by at least one memory.

The storage module, the processing module and the transceiver module may exist separately, or may be integrated in whole or in part, for example, the storage module and the processing module are integrated, or the processing module and the transceiver module are integrated, etc.

Fig. 10 is a schematic structural diagram of a fault switching device according to an embodiment of the present application. The fault back-off device may be used to implement a function corresponding to the first PE or the remote PE in the above method embodiment, for example, may be a PE, or may be a device capable of supporting the PE to implement a function corresponding to the above method embodiment.

The communication device may include a processor 1001, a communication interface 1002, and a memory 1003. The communication interface 1002 is used to communicate with other devices through a transmission medium, and the communication interface 1002 may be a transceiver, or may be an interface circuit such as a transceiver circuit, a transceiver chip, or the like. The memory 1003 is used for storing program instructions and/or data, and the processor 1001 is used for executing the program instructions stored in the memory 1003, so as to implement the method in the above-mentioned method embodiment. In the alternative, memory 1003 is coupled to processor 10901, which is an indirect coupling or communication connection between devices, elements, or modules, whether electrical, mechanical, or otherwise, for information interaction between the devices, elements, or modules.

In one embodiment, the communication interface 1002 may be specifically configured to perform the actions of the transceiver module 1010, and the processor 1001 may be specifically configured to perform the actions of the processing module 1020, which are not described herein.

The specific connection medium between the communication interface 1002, the processor 1001, and the memory 1003 is not limited in the embodiments of the present application. In the embodiment of the present application, the memory 1003, the processor 1001 and the communication interface 1002 are connected by a bus 1004 in fig. 10, where the bus is indicated by a thick line in fig. 10, and the connection manner between other components is only schematically illustrated, and is not limited thereto. The buses may be classified as address buses, data buses, control buses, etc. For ease of illustration, only one thick line is shown in fig. 10, but not only one bus or one type of bus.

The embodiment of the application also provides a chip system, which comprises: and a processor coupled to the memory, the memory for storing a program or instructions that, when executed by the processor, cause the system-on-chip to implement the method of the corresponding terminal or the method of the corresponding network device in any of the method embodiments described above.

Alternatively, the processor in the system-on-chip may be one or more. The processor may be implemented in hardware or in software. When implemented in hardware, the processor may be a logic circuit, an integrated circuit, or the like. When implemented in software, the processor may be a general purpose processor, implemented by reading software code stored in a memory.

Alternatively, the memory in the system-on-chip may be one or more. The memory may be integral with the processor or separate from the processor, and is not limited in this application. For example, the memory may be a non-transitory processor, such as a ROM, which may be integrated on the same chip as the processor, or may be separately provided on different chips, and the type of memory and the manner of providing the memory and the processor are not specifically limited in this application.

The system-on-chip may be, for example, a field programmable gate array (field programmable gate array, FPGA), an application specific integrated chip (application specific integrated circuit, ASIC), a system on chip (SoC), a central processing unit (central processor unit, CPU), a network processor (network processor, NP), a digital signal processing circuit (digital signal processor, DSP), a microcontroller (micro controller unit, MCU), a programmable controller (programmable logic device, PLD) or other integrated chip.

It should be understood that the steps in the above-described method embodiments may be accomplished by integrated logic circuitry in hardware in a processor or instructions in the form of software. The steps of a method disclosed in connection with the embodiments of the present application may be embodied directly in a hardware processor or in a combination of hardware and software modules in a processor.

Embodiments of the present application also provide a computer-readable storage medium having stored therein computer-readable instructions, which when read and executed by a computer, cause the computer to perform the method of any of the method embodiments described above.

The present application also provides a computer program product which, when read and executed by a computer, causes the computer to perform the method of any of the method embodiments described above.

The embodiment of the application also provides a communication system, which comprises the CE, the first PE and the second PE. Optionally, the communication system may further include a remote PE. Optionally, a remote CE may be included in the communication system.

It is to be appreciated that the processors referred to in the embodiments of the present application may be CPUs, but may also be other general purpose processors, DSP, ASIC, FPGA or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, or the like. A general purpose processor may be a microprocessor or the processor may be any conventional processor or the like.

It should also be understood that the memory referred to in the embodiments of the present application may be volatile memory or nonvolatile memory, or may include both volatile and nonvolatile memory. The nonvolatile memory may be a read-only memory (ROM), a programmable ROM, an erasable ROM, an electrically erasable ROM, or a flash memory, among others. The volatile memory may be random access memory (random access memory, RAM) which acts as an external cache. By way of example, and not limitation, many forms of RAM are available, such as static random access memory, dynamic random access memory, synchronous dynamic random access memory, double data rate synchronous dynamic random access memory, enhanced synchronous dynamic random access memory, synchronous link dynamic random access memory, and direct memory bus random access memory.

Note that when the processor is a general-purpose processor, DSP, ASIC, FPGA or other programmable logic device, discrete gate or transistor logic device, discrete hardware components, the memory (storage module) is integrated into the processor.

It should be noted that the memory described herein is intended to comprise, without being limited to, these and any other suitable types of memory.

It should be understood that, the various numbers related to the various embodiments of the present application are merely for convenience of description, and the size of the sequence numbers of the above-mentioned processes or steps does not mean that the execution sequence of the processes or steps should be determined by the functions and inherent logic thereof, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Those of ordinary skill in the art will appreciate that the various illustrative elements and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, or combinations of computer software and electronic hardware. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.

It will be clear to those skilled in the art that, for convenience and brevity of description, specific working procedures of the above-described systems, apparatuses and units may refer to corresponding procedures in the foregoing method embodiments, and are not repeated herein.

In the several embodiments provided in this application, it should be understood that the disclosed systems, devices, and methods may be implemented in other manners. For example, the apparatus embodiments described above are merely illustrative, e.g., the division of the units is merely a logical function division, and there may be additional divisions when actually implemented, e.g., multiple units or components may be combined or integrated into another system, or some features may be omitted or not performed. Alternatively, the coupling or direct coupling or communication connection shown or discussed with each other may be an indirect coupling or communication connection via some interfaces, devices or units, which may be in electrical, mechanical or other form.

The units described as separate units may or may not be physically separate, and units shown as units may or may not be physical units, may be located in one place, or may be distributed on a plurality of network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

In addition, each functional unit in each embodiment of the present application may be integrated in one processing unit, or each unit may exist alone physically, or two or more units may be integrated in one unit.

The functions, if implemented in the form of software functional units and sold or used as a stand-alone product, may be stored in a computer-readable storage medium. Based on such understanding, the technical solution of the present application may be embodied essentially or in a part contributing to the prior art or in a part of the technical solution, in the form of a software product stored in a storage medium, including several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the methods described in the embodiments of the present application. And the aforementioned storage medium includes: a usb disk, a removable hard disk, a ROM, a RAM, a magnetic disk, or an optical disk, etc.

In the various embodiments of the application, if there is no specific description or logical conflict, terms and/or descriptions between the various embodiments are consistent and may reference each other, and features of the various embodiments may be combined to form new embodiments according to their inherent logical relationships.

Claims

1. A method of fault back-switching in an ethernet virtual private network, the method comprising:

The method comprises the steps that a first operator edge device PE determines that a designated forwarder DF corresponding to a user edge device CE is switched to a non-designated forwarder non DF, the CE accesses the first PE and the second PE, and the first PE and the second PE work in a single-activity mode;

the first PE sends a first route notification message to a remote PE, wherein the first route notification message is used for notifying first MAC route information of the CE, and is also used for notifying the priority of the first MAC route information and that the priority of the first MAC route information is lower than a preset priority, so that the remote PE determines a new forwarding path for the message sent to the CE according to the priorities of the route information of the CE.

2. The method of claim 1, wherein if the remote PE is an IBGP neighbor of the first PE, the priority of the first MAC routing information is indicated by a LOCAL priority local_pref attribute of the first MAC routing information;

the priority of the first MAC routing information is lower than a preset priority, including:

and the attribute value of the local_pref attribute of the first MAC routing information is smaller than the attribute value of the local_pref attribute corresponding to the preset priority.

3. The method of claim 1, wherein if the remote PE is an EBGP neighbor of the first PE, the priority of the first MAC routing information is indicated by a multi-exit identification, MED, attribute of the first MAC routing information;

and the attribute value of the MED attribute of the first MAC routing information is larger than the attribute value of the MED attribute corresponding to the preset priority.

4. A method for fault back-switching in an ethernet virtual private network EVPN, the method comprising:

the method comprises the steps that a remote operator edge equipment PE receives a route notification message from a second PE, wherein the route notification message is used for notifying second MAC route information of a user edge equipment CE, the CE is connected to a first PE and the second PE, and the first PE and the second PE work in a single-active mode;

if the second MAC routing information is the last received MAC routing information of the CE, the remote PE determines to forward the message of the CE through the second PE according to the second MAC routing information.

5. A fault reclosing device, the device comprising:

The processing module is used for determining that a designated forwarder DF corresponding to a customer edge equipment CE is switched into a non-designated forwarder non DF, the CE is accessed to the device and a second operator edge equipment PE, and the device and the second PE work in a single-activity mode;

the receiving and transmitting module is used for sending a first route notification message to a far-end PE, wherein the first route notification message is used for notifying first MAC route information of the CE, and is also used for notifying the priority of the first MAC route information and that the priority of the first MAC route information is lower than a preset priority, so that the far-end PE determines a new forwarding path for the message sent to the CE according to the priority of each route information of the CE.

6. The apparatus of claim 5, wherein if the remote PE is an IBGP neighbor of the apparatus, the priority of the first MAC routing information is indicated by a LOCAL priority local_pref attribute of the MAC routing information, and the attribute value of the local_pref attribute of the first MAC routing information is less than the attribute value of the local_pref attribute corresponding to the preset priority.

7. The apparatus of claim 5, wherein if the remote PE is an EBGP neighbor of the external border gateway protocol of the apparatus, the priority of the first MAC routing information is indicated by a multi-exit identification MED attribute of the first MAC routing information, and an attribute value of the MED attribute of the first MAC routing information is greater than an attribute value of the MED attribute corresponding to the preset priority.

8. A fault reclosing device, the device comprising:

the receiving and transmitting module is used for receiving a route notification message from a second operator edge equipment PE, wherein the route notification message is used for notifying second MAC route information of a user edge equipment CE, the CE is accessed to a first PE and a second PE, and the first PE and the second PE work in a single-active mode;

and the processing module is used for determining that the message forwarded by the CE through the second PE according to the second MAC routing information if the second MAC routing information is determined to be the last received MAC routing information of the CE.

9. A fault cut-back apparatus, the apparatus comprising at least one processor coupled to at least one memory:

the at least one processor configured to execute a computer program or instructions stored in the at least one memory to cause the apparatus to perform the method of any one of claims 1 to 3 or to cause the apparatus to perform the method of claim 4.

10. A computer readable storage medium storing instructions which, when executed, cause the method of any one of claims 1 to 3 to be implemented or cause the method of claim 4 to be implemented.

11. The fault back-switching device is characterized by comprising a processor and an interface circuit;

the interface circuit is used for interacting code instructions or data with the processor;

the processor is for performing the method of any one of claims 1 to 3 or for performing the method of claim 4.