CN110391987B

CN110391987B - Method, apparatus and computer readable medium for selecting a designated forwarder from a carrier edge device set

Info

Publication number: CN110391987B
Application number: CN201810346481.XA
Authority: CN
Inventors: 张立新
Original assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Current assignee: Nokia Shanghai Bell Co Ltd; Nokia Solutions and Networks Oy
Priority date: 2018-04-16
Filing date: 2018-04-16
Publication date: 2022-05-10
Anticipated expiration: 2038-04-16
Also published as: CN110391987A

Abstract

Embodiments of the present disclosure relate to methods, devices, and computer-readable media for selecting a Designated Forwarder (DF) from a set of operator edge (PE) devices. According to embodiments of the present disclosure, a PE device may dynamically select a designated forwarder from a redundant set of PE devices through a new designated forwarder selection type and algorithm. In this way, the IP multicast traffic introduced by the VRRP protocol in the EVPN is effectively avoided.

Description

Method, apparatus and computer readable medium for selecting a designated forwarder from a carrier edge device set

Technical Field

Embodiments of the present disclosure relate generally to communication technology and, more particularly, relate to a method, apparatus, and computer-readable medium for selecting a Designated Forwarder (DF) from a set of operator edge devices (PEs).

Background

In today's networks, data centers are increasingly being used for data exchange and resource sharing. Data centers include network elements such as hosts, load balancers, routers, switches, and the like to provide resource access and sharing. Meanwhile, a technology for establishing a Virtual Private Network (VPN) on a public wide area network to enable remote interconnection and access is also being developed. For example, the industry has proposed Ethernet Virtual Private Network (EVPN) technology that is considered to be the next generation integrated VPN. Virtual private network technologies such as EVPN are continuously being developed.

Disclosure of Invention

In general, embodiments of the present disclosure relate to methods of reducing IP multicast traffic in wide area networks and data centers, and corresponding devices.

In a first aspect, embodiments of the present disclosure provide a communication method. The method comprises the following steps: obtaining, at a Provider Edge (PE) device of a set of PE devices, control information for the PE device related to a specified forwarder selection, the control information comprising a field indicating a link status between the PE device and a Customer Edge (CE) device; determining link state information between the PE device and the CE device from a field of link state; obtaining link state information between other PE equipment in the PE equipment set and the CE; and selecting the PE device as a designated repeater from the PE device set, wherein the selected PE device has link state information indicating that the link state is normal.

In a second aspect, embodiments of the present disclosure provide an operator edge (PE) device. The PE device comprises: at least one processor; and a memory coupled with the at least one processor, the memory having instructions stored therein that, when executed by the at least one processor, cause the PE device to perform acts comprising: obtaining, at a Provider Edge (PE) device of a set of PE devices, control information for the PE device related to a specified forwarder selection, the control information comprising a field indicating a link status between the PE device and a Customer Edge (CE) device; determining link state information between the PE device and the CE device from a field of link state; obtaining link state information between other PE equipment in the PE equipment set and the CE; and selecting the PE device as a designated repeater from the PE device set, wherein the selected PE device has link state information indicating that the link state is normal.

In a third aspect, embodiments of the present disclosure provide a computer-readable storage medium. The computer readable storage medium comprises program code stored thereon, which when executed by an apparatus, causes the apparatus to perform the method according to the first aspect.

It should be understood that the statements herein reciting aspects are not intended to limit the critical or essential features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become apparent from the following description.

Drawings

The above and other features, advantages and aspects of various embodiments of the present disclosure will become more apparent by referring to the following detailed description when taken in conjunction with the accompanying drawings, in which:

FIG. 1 illustrates a block diagram of an example computer network architecture in which embodiments of the present disclosure may be implemented;

FIG. 2 shows a schematic diagram of a computer network architecture;

FIG. 3 illustrates a schematic diagram of a computer network architecture, in accordance with certain embodiments of the present disclosure;

FIG. 4 illustrates a flow diagram of an example method in accordance with certain embodiments of the present disclosure;

FIG. 5 illustrates a schematic diagram of an extended community field, in accordance with certain embodiments of the present disclosure; and

fig. 6 illustrates a block diagram of a communication device, in accordance with certain embodiments of the present disclosure.

The same or similar reference numbers are used throughout the drawings to refer to the same or like elements.

Detailed Description

Embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. While certain embodiments of the present disclosure are shown in the drawings, it is to be understood that the present disclosure may be embodied in various forms and should not be construed as limited to the embodiments set forth herein, but rather are provided for a more thorough and complete understanding of the present disclosure. It should be understood that the drawings and embodiments of the disclosure are for illustration purposes only and are not intended to limit the scope of the disclosure.

The term "Provider Edge (PE) device" as used herein is a router that is deployed at the Edge of an operator's network and provides a variety of network services. In a data center that supports Network Virtualization, software-based or hardware-based Network Virtualization Edge (NVE) devices have the same functionality. Thus, the PE devices described herein also encompass NVE devices of a data center. The network operator is also typically an internet service operator or a data center operator.

The term "Customer Edge (CE) device" as used herein is a Customer device, including a host, switch, or router, connected to an Edge of a carrier IP/MPLS network. The CE device is connected with the PE device in an equal-pair mode and communicates with the corresponding VRF or MAC-VRF in the PE device. In a data center environment, the CE may be a client-specific server or may be a client virtual machine hosted in a data center common server.

The terms "include" and variations thereof as used herein are inclusive and open-ended, i.e., "including but not limited to. The term "based on" is "based, at least in part, on". The term "one embodiment" means "at least one embodiment"; the term "another embodiment" means "at least one additional embodiment". Relevant definitions for other terms will be given in the following description.

FIG. 1 illustrates an example computer network architecture 100 in which embodiments of the present disclosure may be implemented. In this example, computer network architecture 100 includes PE device 110-1, PE device 110-2, a. The set of PE devices 110 may be located in an operator network 140. The set of PE devices 110 may be referred to as a set of redundant PE devices. The CE device 120 is located in the customer network 130. The user network 130 may also include any other suitable devices such as network termination devices (not shown). It is to be appreciated that the number of PE devices in the set of PE devices 110 and the number of CE devices 120 shown in fig. 1 are merely exemplary and that any suitable number of PE devices may be included in the computer network architecture 100. The network terminal equipment is connected with the PE equipment through the CE equipment.

PE devices (e.g., PE devices 110-1, 110-2) in PE device set 110 shown in fig. 1 may be connected to each other directly or through operator devices. In some cases, EVPN instances of a user subnetwork may be connected to a Wide Area Network (WAN) via a set of Redundant (RG) three-tier (L3) virtual devices (VA). The PE device 110-1, the PE device 110-2. The conventional Router Redundancy solution generally selects one Router as a primary Router and other routers as standby routers through a vrrp (virtual Router Redundancy protocol) protocol. The VRRP protocol needs to exchange IP multicast messages among multiple redundant routers, and if VRRP is used to select a primary router among three layers of virtual devices, the IP multicast traffic of the data center network will inevitably increase. Generally, in a data center network, broadcast or multicast traffic should be avoided as much as possible.

According to an embodiment of the present disclosure, fields of control information related to a designated repeater selection in a PE device are redefined so that one PE device in an RG can be dynamically selected as a designated repeater in different ways. This way multicast traffic introduced by the VRRP protocol is effectively avoided.

Fig. 2 exemplarily shows a structure diagram of redundancy L3VA in EVPN. As shown in FIG. 2, PE device 210-1 and PE device 210-2 are connected to CE device 220. PE device 210-1 and PE device 210-2 are both located in the data center network 250 and belong to the same RG. Data center network 250 is connected to a Wide Area Network (WAN) via a data center gateway (DGW). PE device 210-1 and PE device 210-2 each have an L3VA running thereon.

As shown in fig. 2, PE device 210-1 and PE device 210-2 are each connected to a CE via a respective MAC-VRF entity. PE device 210-1 and PE device 210-2 also communicate with the data center gateway through a MAC-VRF entity of the auxiliary broadcast domain (SBD). As described above, CE device 220 is multi-homed to PE device 210-1 and PE device 210-2, and therefore a Designated Forwarder (DF) needs to be selected between PE device 210-1 and PE device 210-2. In this scenario, the conventional VRRP protocol that exchanges control information based on IP multicast traffic is not suitable.

Fig. 3 shows a schematic diagram of a computer network architecture 300 according to an embodiment of the present disclosure. It is to be appreciated that the network components shown in fig. 3 are merely exemplary, and that the computer network architecture 300 may also include any other network components not shown, such as the computer network architecture 300 may also include a WAN (not shown). The number of network components shown in fig. 3 is also merely exemplary, and the computer network architecture 300 may include any suitable number of network components, e.g., the computer network architecture 300 may include more than one CE device.

As shown in fig. 3, CE device 120 may be connected to PE device 110-1 and PE device 110-2, respectively. There is an Access Circuit (AC) between the CE device 120 and the PE devices in the set of PE devices 110. For example, there is an AC 340-1 between CE device 120 and PE device 110-1, and an AC 340-2 between CE device 120 and PE device 110-2. When an AC fails, the CE device 120 will be unable to communicate with the corresponding PE device through the failed AC.

The PE devices in PE device set 110 have customer subnetwork MAC-VRF 3120 and are also implemented thereon by L3VA 3110. Among the PE devices in the PE device set 110, the MAC-VRF 3120 is connected with L3VA 3110 via an interface. For example, in PE device 110-1, customer subnetwork MAC-VRF connects with L3VA 3310 via interface 330-1. In PE device 110-2, a customer subnetwork MAC-VRF connects with L3VA 3310 via interface 330-2. In certain embodiments, the interface connecting MAC-VRF 3120 and L3VA 3110 may be an Integrated Routing and Bridging (IRB) interface. It is to be appreciated that MAC-VRF 3120 may interface with L3VA 3110 via any suitable interface. The term "Ethernet Segment" as used herein refers to a set of interfaces, such as interfaces 330-1 and 330-2, that connect MAC-VRF 3120 and L3VA 3110. This is different from the common ethernet segment in general EVPN. An ethernet segment, which is common in EVPN, refers to the CE device to MAC-VRF link. In the embodiments of the present disclosure, for the purpose of explanation. The ethernet segments correspond one-to-one to the sets of redundancy L3 VA.

Each Ethernet Segment has an Ethernet Segment Identifier (ESI). The ESIs belonging to the same client subnet are the same. In some embodiments, the ESI may be manually configured to a client subnet. In other embodiments, the ESIs may also be dynamically generated by PE device 110-1 and PE device 110-2, respectively, according to predetermined rules. The ESIs generated by PE device 110-1 and PE device 110-2 are the same. Different example ESI formats under different internet protocol versions will be described below. It is to be understood that the ESI format described below is exemplary only, and not limiting. The ESI may have any suitable format.

In some embodiments using the IPv4 Internet protocol, the ESI can be encoded as follows. The 1 byte ESI type field contains T _ IPv 4. The top 4 bytes of the ESI value field include the virtual IPv4 address of the redundancy L3VA, the next 4 bytes include a local specifier, and the lowest byte is set to 0.

In some embodiments using the IPv6 Internet protocol, the ESI can be encoded as follows. The 1 byte ESI type field contains T _ IPv 6. The top 8 bytes of the ESI value field contain the lower 64 bits of the virtual IPv6 address (i.e., interface identifier) of the redundancy L3VA, with the lowest byte including the local specifier.

Fig. 4 shows a flow diagram of a method 400 according to an embodiment of the present disclosure. The method 400 shown in fig. 4 may be implemented at any PE device in the set of PE devices 110 shown in fig. 1 and 3. The implementation of embodiments of the present disclosure at PE device 110-1 is described below for convenience of illustration only.

At 410, PE device 110-1 obtains control information for the PE device regarding the designated repeater selection. For example, PE device 110-1 may obtain control information, such as an ES-input routing target extended community (ES-Import RT extended community), for PE device set 110. The ES-input value of the ES-input route target extended community is extracted from the top 6 bytes of the ESI value field. PE device 110-1 also has an incoming route target filter for the same route target value as the ES-incoming route target expansion community. In some embodiments, the PE device 110-1 may belong to multiple RGs. In such an example, the PE device 110-1 obtains different designated repeater selection control information for each RG.

The designated forwarder selection control information includes a field indicating a link state between the PE device 110-1 and the CE device 120. As shown in fig. 3, an AC 340-1 exists between PE device 110-1 and CE device 120. If AC 340-1 is normal, it indicates that the link between PE device 110-1 and CE device 120 can perform normal data exchange. If AC 340-1 fails, no data exchange can occur between PE device 110-1 and CE device 120. As described above, in embodiments of the present disclosure, the link between PE device 110-1 and CE device 120 is not involved due to the ethernet segment. Accordingly, embodiments of the present disclosure add a flag bit to indicate the link status. As will be further described below with reference to fig. 5.

Fig. 5 shows a schematic diagram of a field format of the designated repeater selection control information 500 according to an embodiment of the present disclosure. In contrast to the prior art, the portion of the field format of the designated repeater selection control information 500 is redefined. For purposes of illustration only, the designated forwarder election control information may elect an extended community for the EVPN DF. The field format shown in fig. 5 is exemplary only, and not limiting.

In some embodiments, the field portion 5010 of the control information indicating the DF type is redefined. For example, in the existing EVPN related protocol,

DF type

0, 1 and 2 values respectively represent different DF election methods. In an embodiment of the present disclosure, the value of DF type may be set to be greater than 2. The field part 5010 of the DF type may be defined autonomously by an operator and may also be defined according to a corresponding protocol standard.

At 420, PE device 110-1 determines link state information between it and the CE device from the fields of link state. For example, as shown in FIG. 5, a newly defined ACS (Access Circuit State) field portion 5020 may indicate the link state between PE device 110-1 and CE device 120. As an example, ACS field portion 5020 is 0 if the link between PE device 110-1 and CE device 120 is normal. The ACS field portion 5020 is 1 if the link between the PE device 110-1 and the CE device 120 fails. It is to be appreciated that the ACS field portion 5020 may indicate the link state between the PE device 110-1 and the CE device 120 in any suitable manner.

Alternatively or additionally, the control information may also include a field indicating the priority of PE device 110-1 as a DF. PE device 110-1 may determine its priority as the designated forwarder based on a priority field in the control information. For example, in some embodiments, as shown in fig. 5, DF Preference field portion 5030(DF _ Preference) may indicate the priority of PE device 110-1 as the DF. For example, if PE device 110-1 has a higher priority, DF preference field portion 5030 has a larger value. In some embodiments, PE device 110-1 may indicate that other PE devices are not to attempt to preempt the DF by setting DP field 5040. It is to be appreciated that PE device 110-1 may also be prioritized as a DF by other suitable means, such as based on geographical location information, etc.

In this way, embodiments of the present disclosure enable the selection of DF in the RG of L3VA by redefining the field specifying the repeater selection control information, thereby avoiding IP multicast traffic introduced by the VRRP protocol in EVPN.

At 430, PE device 110-1 obtains link state information for other PE devices in PE device set 110 (e.g., PE device 110-2). In some embodiments, PE device 110-1 may receive link state information directly from other PE devices in PE device set 110. PE device 110-1 may also access a storage device that stores link state information for other PE devices to obtain the link state information.

At 440, PE device 110-1 selects a PE device from PE device set 110 as the designated forwarder. PE device 110-1 may select a PE device as the designated repeater based on the obtained link state information. That is, PE device 110-1 may take a PE device of the set of PE devices 110 that has a normal link connection with CE device 120 as the designated forwarder.

In some embodiments, if PE device 110-1 determines that only the link between itself and the CE device in the set of PE devices 110 is normal, PE device 110-1 selects itself as the designated forwarder. In this way, the PE device in the RG that is the DF can be quickly determined with minimal resource consumption (e.g., computational resources). In some embodiments, if the links of multiple PE devices in the PE device set 110 are normal, the screening may be continued.

As described above, in some embodiments, there may be multiple PE devices in the PE device set 110 that have normal connection links with the CE, and the PE device 110-1 may further determine which PE device should become the DF according to the DF priority of each PE device in the PE device set 110. For example, PE device 110-1 may select the PE device with the highest DF priority as the DF. If there are multiple PE devices in the set of PE devices 110 with the same priority, the selection should continue.

In some embodiments, PE device 110-1 may determine which PE device should become the DF according to the IP address information of each PE device in the set of PE devices. For example, PE device 110-1 may select the PE device with the smallest IP address numerical value as the DF. In some embodiments, PE device 110-1 may select the PE device with the largest IP address numerical value as the DF.

In some embodiments, link state information of the PE device, priority of the PE device as a designated forwarder, and control information regarding the selection of the designated forwarder, such as the IP address of the PE device, may be stored and transmitted in a manner such as a list. For example, the control information for each PE device regarding the selection of a given transponder may be one triple data item in the list. In some embodiments, if the PE device 110-1 belongs to different RGs at the same time, the PE device 110-1 may store the above-mentioned control information of all PE devices in the PE device set 110 in the form of a list after obtaining the above-mentioned control information on the designated repeater selection for all PE devices, and the list is stored in association with the ESI values of the PE device set 110.

In some embodiments, PE device 110-1 may send the current location information of the DF to CE device 120. For example, if PE device 110-1 determines itself as the DF in the set of PE devices 110, PE device 110-1 may send information to the CE device indicating that its link with the CE device should be in an active state. In another embodiment, the PE device 110-1 may also send PE device specific information (e.g., virtual MAC address) to be the DF to the CE device, etc.

In some embodiments, if the CE device 120 is a host, the PE device acting as the DF needs to signal each AC status to the CE device 120. If CE device 120 is an Ethernet switch, the PE device acting as the DF needs to update the forwarding database of CE device 120 to update the current location of the virtual MAC address of virtual L3 VA.

In some embodiments, the reselection of the DF should be triggered if a change in control information of a PE device in the set of PE devices 110 regarding the designated forwarder selection occurs. For example, a link state change between PE device 110-1 and/or PE device 110-2 and CE device 120 may trigger a reselection of the DF. In certain embodiments, a change in priority of PE device 110-1 and/or PE device 110-2 as a DF may also trigger a reselection of a DF. In other embodiments, the reselection of the DF may also be triggered if the PE device IP address in the set of PE devices has changed. In some embodiments, if the reselected DF is the same as the original DF, the PE devices in the set of PE devices do not need to send the reselected DF information to the CE. In other embodiments, if the reselected DF changes from the original DF, the PE device newly determined as the DF should send information to the CE indicating that the link connection between the two is active. The PE, as the original DF, needs to send information to the CE indicating that the link connection between the two is inactive.

Fig. 6 is a block diagram of a device 600 in which embodiments according to the present disclosure may be implemented. As shown in fig. 6, the device 600 includes one or more processors 610 and one or more memories 620 coupled to the processors 610.

The processor 610 may be of any suitable type suitable to the local technical environment, and the processor 610 may include, by way of non-limiting example, one or more general purpose computers, special purpose computers, microprocessors, digital signal processors, and processors based on a multi-core processor architecture. The device 600 may have multiple processors, such as application specific integrated circuit chips, that are synchronized in time with the main processor.

The memory 620 may be of any suitable type suitable to the local technical environment and may be implemented using any suitable data storage technology, including but not limited to non-transitory computer-readable media, semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems.

The memory 620 stores at least a portion of the instructions 630. The device 600 may receive control information related to a designated repeater selection.

The instructions 630 are assumed to comprise program instructions that, when executed by the associated processor 610, cause the device 600 to operate in accordance with the embodiments described in this disclosure with reference to fig. 4 and 5. That is, embodiments of the present disclosure may be implemented by the processor 610 of the device 600, by computer software execution, or by hardware, or by a combination of software and hardware.

In general, the various example embodiments of this disclosure may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. Certain aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device. While aspects of embodiments of the disclosure have been illustrated or described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that the blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

By way of example, embodiments of the disclosure may be described in the context of machine-executable instructions, such as those included in program modules, being executed in a device on a target real or virtual processor. Generally, program modules include routines, programs, libraries, objects, classes, components, data structures, etc. that perform particular tasks or implement particular abstract data types. In various embodiments, the functionality of the program modules may be combined or divided between program modules as described. Machine-executable instructions for program modules may be executed within local or distributed devices. In a distributed facility, program modules may be located in both local and remote memory storage media.

Computer program code for implementing the methods of the present disclosure may be written in one or more programming languages. These computer program codes may be provided to a processor of a general purpose computer, special purpose computer, or other programmable data processing apparatus, such that the program codes, when executed by the computer or other programmable data processing apparatus, cause the functions/acts specified in the flowchart and/or block diagram block or blocks to be performed. The program code may execute entirely on the computer, partly on the computer, as a stand-alone software package, partly on the computer and partly on a remote computer or entirely on the remote computer or server.

In the context of this disclosure, a machine-readable medium may be any tangible medium that can contain, or store a program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium may be a machine-readable signal medium or a machine-readable storage medium. A machine-readable medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination thereof. More detailed examples of a machine-readable storage medium include an electrical connection having one or more wires, a portable computer diskette, a hard disk, a Random Access Memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or flash memory), an optical storage device, a magnetic storage device, or any suitable combination thereof.

Additionally, while operations are depicted in a particular order, this should not be understood as requiring that such operations be performed in the particular order shown or in sequential order, or that all illustrated operations be performed, to achieve desirable results. In some cases, multitasking or parallel processing may be beneficial. Likewise, while the above discussion contains certain specific implementation details, this should not be construed as limiting the scope of any invention or claims, but rather as describing particular embodiments that may be directed to particular inventions. Certain features that are described in this specification in the context of separate embodiments can also be implemented in combination in a single embodiment. Conversely, various features that are described in the context of a single embodiment can also be implemented in multiple embodiments separately or in any suitable subcombination.

Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.

Claims

1. A method of communication, comprising:

obtaining, at a PE device of a set of operator edge PE devices, control information of the PE device regarding a designated forwarder DF election, the control information including a field indicating a link state between the PE device and a customer edge CE device, the control information further including an Ethernet segment-ingress routing target extension community, wherein the Ethernet segment is in one-to-one correspondence with the set of PE devices where the PE device is located;

determining link state information between the PE device and the CE device from a field of the link state;

obtaining link state information between other PE devices in the PE device set and the CE; and

and selecting the PE equipment as a designated repeater from the PE equipment set, wherein the selected PE equipment has link state information indicating that the link state is normal.

2. The method of claim 1, wherein the control information further comprises a field indicating a priority of the PE device as the designated forwarder.

3. The method of claim 2, wherein selecting a PE device of a designated repeater from the set of PE devices comprises:

determining the priority of the PE device as a designated repeater from the field of the priority;

obtaining the priority of other PE devices in the PE device set as a designated repeater; and

selecting a PE device from the determined PE devices as the designated forwarder, the selected PE device having a highest priority as the designated forwarder.

4. The method of claim 1, wherein selecting a PE device from the set of PE devices as a designated forwarder comprises:

obtaining an Internet Protocol (IP) address of the PE equipment;

obtaining IP addresses of other PE devices in the PE device set; and

performing at least one of:

selecting the PE equipment as the appointed forwarder from the determined PE equipment, wherein the selected PE equipment has the IP address with the lowest numerical value; and

selecting the PE device as the designated forwarder from the determined PE devices, wherein the selected PE device has the IP address with the highest numerical value.

5. The method of claim 1, wherein the control information further comprises another field indicating that the PE device is capable of supporting selection of the designated forwarder.

6. The method of claim 1, further comprising:

transmitting current location information relating to the designated repeater to the CE device.

7. The method of claim 1, further comprising:

transmitting, to the other PE devices in the set of PE devices, at least one of: the link state information of the PE, the priority of the PE as the designated forwarder, and the IP address of the PE device.

8. A carrier edge, PE, device comprising:

at least one processor; and

a memory coupled with the at least one processor, the memory having instructions stored therein that, when executed by the at least one processor, cause the PE device to perform acts comprising:

obtaining, at a PE device of a set of PE devices, control information of the PE device regarding a designated forwarder selection, the control information including a field indicating a link status between the PE device and a Customer Edge (CE) device, the control information further including an Ethernet segment-ingress routing target extension community, wherein the Ethernet segments are in one-to-one correspondence with the set of PE devices where the PE device is located;

and selecting the PE equipment of the specified repeater from the PE equipment set, wherein the selected PE equipment has link state information indicating that the link state is normal.

9. The device of claim 8, wherein the control information further comprises a field indicating a priority of the PE device as the designated forwarder.

10. The device of claim 9, wherein selecting a PE device of a designated forwarder from the set of PE devices comprises:

selecting a PE device from the determined PE devices as the designated forwarder, the selected PE device having a high priority as the designated forwarder.

11. The device of claim 8, wherein selecting a PE device of a designated forwarder from the set of PE devices comprises:

obtaining an Internet Protocol (IP) address of the PE equipment;

obtaining IP addresses of other PE devices in the PE device set; and

performing at least one of:

and selecting the PE equipment as the designated forwarder from the determined PE equipment, wherein the selected PE equipment has the IP address with the highest value.

12. The device of claim 8, wherein the control information further comprises another field indicating that the PE device is capable of supporting selection of the designated forwarder.

13. The apparatus of claim 8, further comprising:

14. The apparatus of claim 8, further comprising:

15. A computer-readable medium having instructions stored thereon, which, when executed by at least one processing unit of a machine, cause the machine to implement the method recited by any one of claims 1-7.