WO2023011149A1 - 一种基于第6版互联网协议的段路由SRv6的通信方法 - Google Patents

一种基于第6版互联网协议的段路由SRv6的通信方法 Download PDF

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Publication number
WO2023011149A1
WO2023011149A1 PCT/CN2022/106169 CN2022106169W WO2023011149A1 WO 2023011149 A1 WO2023011149 A1 WO 2023011149A1 CN 2022106169 W CN2022106169 W CN 2022106169W WO 2023011149 A1 WO2023011149 A1 WO 2023011149A1
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gateway
layer
evi
sid
mac
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PCT/CN2022/106169
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English (en)
French (fr)
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任化军
朱彤
王海波
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华为技术有限公司
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Priority to EP22851863.5A priority Critical patent/EP4366264A1/en
Publication of WO2023011149A1 publication Critical patent/WO2023011149A1/zh
Priority to US18/426,585 priority patent/US20240171511A1/en

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/66—Layer 2 routing, e.g. in Ethernet based MAN's
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/02—Topology update or discovery
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/34—Source routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/74—Address processing for routing
    • H04L45/741—Routing in networks with a plurality of addressing schemes, e.g. with both IPv4 and IPv6
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/74—Address processing for routing
    • H04L45/745—Address table lookup; Address filtering
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L61/00—Network arrangements, protocols or services for addressing or naming
    • H04L61/09—Mapping addresses
    • H04L61/10—Mapping addresses of different types
    • H04L61/103—Mapping addresses of different types across network layers, e.g. resolution of network layer into physical layer addresses or address resolution protocol [ARP]

Definitions

  • the present application relates to the technical field of communication, and in particular to a communication method based on the 6th version of the Internet protocol segment routing SRv6.
  • VXLAN virtual extensible LAN
  • NVO3 network virtualization layer 3
  • VXLAN is a network virtualization technology widely used in large Layer 2 networks.
  • a logical VXLAN tunnel is established between the source network device and the destination network device, and the media access control (media access control, MAC) address is encapsulated in the user datagram protocol (user datagram protocol, UDP) encapsulation method, that is, the virtual
  • UDP user datagram protocol
  • the original Ethernet message sent by the computer is completely encapsulated in the UDP message, and then encapsulated using the Internet protocol (internet protocol, IP) message header and Ethernet message header of the physical network on the outer layer.
  • IP Internet protocol
  • VXLAN technology is usually used in LAN networks such as campus networks.
  • the applicant's research on VXLAN technology found that it is difficult to expand new services in the campus network using VXLAN technology.
  • packet forwarding in a network using VXLAN technology is based on IP routing, the campus network using VXLAN technology cannot be optimized for user traffic.
  • this application provides a communication method.
  • the segment routing SRv6 based on version 6 Internet protocol is deployed on the network side, that is, by deploying SRv6( In particular, deploy SRv6-BE) to replace VXLAN for forwarding traffic.
  • SRv6 In particular, deploy SRv6-BE
  • the second-tier gateway will send a large number of Useless Ethernet EVPN host MAC routing causes heavy pressure on Layer 3 gateway MAC routing.
  • the present application also provides methods in the following aspects.
  • the embodiment of the present application proposes a communication method based on the 6th version of the Internet Protocol Segment Routing SRv6, which is executed by a Layer 2 gateway, including: generating a media access control EVI based on an Ethernet virtual private network instance EVI- MAC routing, wherein, the EVI-MAC routing includes the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the SRv6 SID applied for by the EVI at the two-layer gateway, carried in the EVI-MAC routing
  • the MAC address does not include the MAC addresses of the hosts in the EVI; and the EVI-MAC route is published to the layer-3 gateway.
  • Ethernet virtual private network instance Ethernet virtual private network instance, EVI
  • EVI Ethernet virtual private network instance
  • BGP border gateway protocol
  • RFC request for comments
  • each EVI includes one or more hosts, and each EVI forms one or more cross-regional Layer 2 by connecting one or more groups of user networks network. Similar to the Layer 2 gateway, one or more EVIs are deployed (or applied for) in the Layer 3 gateway.
  • segment identifier segment identifier, SID
  • SID segment identifier
  • the SID configured by the two-layer gateway for the EVI is called the EVI SID.
  • the SID applied for in the layer gateway is EVI SID-2.
  • the layer-3 gateway will not receive the MAC address of the host in the layer-2 gateway. Effectively reduce the MAC routing pressure of the Layer 3 gateway. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is an all-F MAC address.
  • the MAC address carried in the EVI-MAC route may be the MAC address of the Layer 2 gateway.
  • the MAC address carried in the EVI-MAC route may also be an all-F MAC address, and the all-F MAC address is also called a MAC address whose field value is all-F.
  • the field value of the MAC address of the route prefix in the MAC route is "0xfffffffffff". It can be understood that the MAC address carried in the EVI-MAC route may also be other field values, which is not limited here.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the layer-2 gateway advertises the host MAC route in the EVI to the layer-3 gateway.
  • the MAC route generated by the Layer 2 gateway does not include the MAC address of the host, and the destination of the MAC route is the Layer 3 gateway.
  • the layer-3 gateway will not receive the MAC address of each host in the layer-2 gateway, thereby preventing the layer-3 gateway from saving the MAC address of the host and reducing the MAC address of the layer-3 gateway Routing stress.
  • the Layer 2 gateway can also be configured so as not to send the MAC address of the host to the Layer 3 gateway, which is not limited here.
  • the layer-2 gateway may publish the MAC route of the hosts in the EVI to the layer-3 gateway, where the MAC route includes the MAC addresses of the hosts in the EVI. At this time, after receiving the MAC route, the layer-3 gateway does not save the MAC addresses of the hosts in the EVI.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the forwarding The above MAC forwarding table.
  • the EVI-MAC route also includes indication information, and the indication information instructs the layer-3 gateway to avoid sending the EVI-MAC route to the MAC forwarding table (forwarding table) of the forwarding plane after receiving the EVI-MAC route.
  • the MAC forwarding table records the mapping relationship between MAC addresses and outgoing interfaces.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the EVI-MAC route may also include an extended community attribute (extended community), and the extended community attribute is used to carry the aforementioned indication information.
  • the layer-3 gateway After receiving the EVI-MAC route, the layer-3 gateway avoids sending the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the extended community attribute of the EVI-MAC route (the extended community attribute carries the indication information) .
  • the indication information may be the extended community attribute, that is, the extended community attribute is used to instruct the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the Layer 2 gateway sends an Address Resolution Protocol ARP request message to the Layer 3 gateway, and the source Internet Protocol SIP address of the ARP request message is The EVI SID; the two-layer gateway receives the ARP response message sent by the three-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the address resolution protocol (address resolution protocol, ARP) protocol is a protocol used to resolve an Internet protocol (Internet protocol, IP) address into a MAC address.
  • IP Internet protocol
  • ARP address resolution protocol
  • the Layer 3 gateway learns the ARP information about the EVI host, the EVI host in the Layer 2 gateway learns the ARP information of the Layer 3 gateway, and the Layer 3 forwarding is reachable between the EVI host in the Layer 2 gateway and the Layer 3 gateway.
  • the EVI SID is an end.dt2u type SID.
  • the SID of type end.dt2u has an endpoint "Endpoint with decapsulation and unicast MAC" for decapsulation and unicast MAC.
  • the SID of type end.dt2u is used for the EVPN Bridging Unicast use case "EVPN Bridging Unicast use case”.
  • the Layer 2 gateway and the Layer 3 gateway are deployed in a campus network.
  • the campus network usually refers to the campus network of a university or the intranet of an enterprise.
  • Main features: The network devices (switches, routers, etc.) and transmission media (fiber optics, etc.) in the campus network are usually owned by the owner of the campus network, such as enterprise users, universities or government agencies.
  • the SRv6 technology can be successfully applied to a LAN network having a Layer 2 gateway and a Layer 3 gateway such as a campus network. This enables the campus network to be optimized for user traffic, improving network bandwidth utilization.
  • SRv6 technology has the advantage of being programmable, so it can effectively reduce the difficulty of implementing new services in the campus network.
  • the Layer 2 gateway performs packet forwarding for SRv6BE based on best-effort IPv6 segment routing.
  • the Layer 2 gateway forwards packets based on the IPv6 segment routing policy SRv6policy.
  • the embodiment of the present application proposes a communication method based on the segment routing SRv6 of the Internet protocol version 6, and the method is executed by a three-layer gateway, including:
  • the EVI-MAC route includes the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the EVI in the The SRv6 SID applied by the two-layer gateway, the MAC address carried in the EVI-MAC route does not include the MAC address of each host in the EVI; according to the EVI SID, obtain the corresponding relationship between the EVI SID and the outgoing interface, and The outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway.
  • Ethernet virtual private network instance Ethernet virtual private network instance, EVI
  • EVI Ethernet virtual private network instance
  • BGP border gateway protocol
  • RFC request for comments
  • each EVI includes one or more hosts, and each EVI forms one or more cross-regional Layer 2 by connecting one or more groups of user networks network. Similar to the Layer 2 gateway, one or more EVIs are deployed (or applied for) in the Layer 3 gateway.
  • the Layer 3 gateway After the Layer 3 gateway receives the EVI-MAC route, it determines that it needs to find the outgoing interface according to the EVI SID carried by the EVI-MAC route.
  • the outbound interface is used by the Layer 3 gateway to send packets whose destination address is EVI SID to the Layer 2 gateway.
  • the SID applied for in the layer gateway is EVI SID-2.
  • the layer-3 gateway will not receive the MAC address of the host in the layer-2 gateway. Effectively reduce the MAC routing pressure of the Layer 3 gateway. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the Layer 3 gateway receives the EVI-MAC route, it determines that it needs to find the outgoing interface according to the EVI SID carried by the EVI-MAC route. The outbound interface is used by the Layer 3 gateway to send packets whose destination address is EVI SID to the Layer 2 gateway.
  • the successful exchange of messages between the layer-2 gateway and the layer-3 gateway is still guaranteed.
  • the obtaining the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID includes: searching a routing table according to the EVI SID to obtain the The corresponding relationship, wherein the routing table includes the corresponding relationship.
  • the layer-3 gateway searches the routing table (routing table) on the forwarding plane to determine the outgoing interface.
  • the routing table is also called routing information table (routing information table) or routing information base (routing information base, RIB).
  • the routing table can be understood as one or more sets of key-value pairs (key-value), and the layer-3 gateway uses the EVI SID as a key to search for the corresponding value in the routing table, which is the outgoing interface.
  • the layer-3 gateway determines the path of the ARP response message according to the outgoing interface.
  • the EVI-MAC route includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the forwarding plane
  • the method further includes: according to the indication of the indication information, avoiding sending the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the MAC forwarding table records the mapping relationship between MAC addresses and outgoing interfaces.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the EVI-MAC route may also include an extended community attribute (extended community), and the extended community attribute is used to carry the aforementioned indication information.
  • the layer-3 gateway After receiving the EVI-MAC route, the layer-3 gateway avoids sending the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the extended community attribute of the EVI-MAC route (the extended community attribute carries the indication information) .
  • the indication information may be the extended community attribute, that is, the extended community attribute is used to instruct the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is an all-F MAC address.
  • the MAC address carried in the EVI-MAC route may be the MAC address of the Layer 2 gateway.
  • the MAC address carried in the EVI-MAC route may also be an all-F MAC address, and the all-F MAC address is also called a MAC address whose field value is all-F.
  • the field value of the MAC address of the route prefix in the MAC route is "0xfffffffffff". It can be understood that the MAC address carried in the EVI-MAC route may also be other field values, which is not limited here.
  • the method further includes: receiving an address resolution protocol ARP request message from the layer-2 gateway, the source of the ARP request message is SIP The address is the EVI SID; according to the corresponding relationship between the EVI SID and the outgoing interface, it is determined to send an ARP response message to the two-layer gateway through the outgoing interface, and the destination Internet Protocol DIP of the ARP response message The address is the EVI SID; the ARP response message is sent to the Layer 2 gateway through the outgoing interface.
  • the address resolution protocol (address resolution protocol, ARP) protocol is a protocol used to resolve an Internet protocol (Internet protocol, IP) address into a MAC address.
  • IP Internet protocol
  • ARP address resolution protocol
  • the source IP (source IP, SIP) address of the ARP request message sent by the second-layer gateway to the third-layer gateway is EVI SID
  • the destination IP (destination IP, DIP) of the ARP response message sent by the third-layer gateway to the second-layer gateway The address is EVI SID.
  • the third-layer gateway obtains the corresponding outbound interface according to the EVI SID, and sends an ARP response message to the second-layer gateway through the outbound interface, thus ensuring that the ARP message between the second-layer gateway and the third-layer gateway can reach the destination smoothly, and the ARP The request process and the ARP reply process can be executed smoothly.
  • the Layer 3 gateway learns the ARP information about the EVI host
  • the EVI host in the Layer 2 gateway learns the ARP information of the Layer 3 gateway
  • the Layer 3 forwarding is reachable between the EVI host in the Layer 2 gateway and the Layer 3 gateway.
  • the EVI SID is an end.dt2u type SID.
  • the SID of type end.dt2u has an endpoint "Endpoint with decapsulation and unicast MAC" for decapsulation and unicast MAC.
  • the SID of type end.dt2u is used for the EVPN Bridging Unicast use case "EVPN Bridging Unicast use case”.
  • the Layer 2 gateway and the Layer 3 gateway are deployed in a campus network.
  • the campus network usually refers to the campus network of a university or the intranet of an enterprise.
  • Main features: The network devices (switches, routers, etc.) and transmission media (fiber optics, etc.) in the campus network are usually owned by the owner of the campus network, such as enterprise users, universities or government agencies.
  • the SRv6 technology can be successfully applied to a LAN network having a Layer 2 gateway and a Layer 3 gateway such as a campus network. This enables the campus network to be optimized for user traffic, improving network bandwidth utilization.
  • SRv6 technology has the advantage of being programmable, so it can effectively reduce the difficulty of implementing new services in the campus network.
  • the layer-3 gateway is a centralized gateway for packet forwarding based on IPv6 segment routing best effort SRv6BE.
  • the Layer 2 gateway forwards packets based on the IPv6 segment routing policy SRv6policy.
  • the embodiment itself proposes a communication method based on the 6th version of the Internet protocol segment routing SRv6, the method is executed by a layer-2 gateway, and the method includes:
  • the source Internet protocol SIP address of the ARP request message is the Ethernet virtual private network instance segment identification EVI SID
  • the EVI SID is the Ethernet virtual private network in the two-layer gateway.
  • the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • an EVPN neighbor is established between the Layer 2 gateway and the Layer 3 gateway through BGP.
  • BGP For the specific establishment process, please refer to the RFC7432 agreement, which will not be described here.
  • each EVI includes one or more hosts, and each EVI forms one or more cross-regional Layer 2 by connecting one or more groups of user networks network. Similar to the Layer 2 gateway, one or more EVIs are deployed (or applied for) in the Layer 3 gateway.
  • the SID applied for in the layer gateway is EVI SID-2.
  • the EVI SID is carried in the ARP request message sent by the second-layer gateway to the third-layer gateway, and the EVI SID is the SID of the EVI.
  • the layer-3 gateway determines the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway. Since the layer-2 gateway no longer sends the MAC address of the EVI host in the layer-2 gateway to the layer-3 gateway, the MAC routing pressure of the layer-3 gateway is effectively reduced. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the third-layer gateway obtains the corresponding outbound interface according to the EVI SID, and sends an ARP response message to the second-layer gateway through the outbound interface, thus ensuring that the ARP message between the second-layer gateway and the third-layer gateway can reach the destination smoothly, and the ARP The request process and the ARP reply process can be executed smoothly.
  • the Layer 3 gateway learns the ARP information about the EVI host, the EVI host in the Layer 2 gateway learns the ARP information of the Layer 3 gateway, and the Layer 3 forwarding is reachable between the EVI host in the Layer 2 gateway and the Layer 3 gateway.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the layer-2 gateway advertises the host MAC route in the EVI to the layer-3 gateway.
  • the MAC route generated by the Layer 2 gateway does not include the MAC address of the host, and the destination of the MAC route is the Layer 3 gateway.
  • the layer-3 gateway will not receive the MAC address of each host in the layer-2 gateway, thereby preventing the layer-3 gateway from saving the MAC address of the host and reducing the MAC address of the layer-3 gateway Routing stress.
  • the Layer 2 gateway can also be configured not to send the MAC address of the host to the Layer 3 gateway, which is not limited here.
  • the layer-2 gateway may publish the MAC route of the hosts in the EVI to the layer-3 gateway, where the MAC route includes the MAC addresses of the hosts in the EVI. At this time, after receiving the MAC route, the layer-3 gateway does not save the MAC addresses of the hosts in the EVI.
  • the EVI SID is an end.dt2u type SID.
  • the SID of type end.dt2u has an endpoint "Endpoint with decapsulation and unicast MAC" for decapsulation and unicast MAC.
  • the SID of type end.dt2u is used for the EVPN Bridging Unicast use case "EVPN Bridging Unicast use case”.
  • the method further includes: generating an EVI-based media access control EVI-MAC route, where the EVI-MAC route includes the EVI SID, the MAC address carried in the EVI-MAC route does not include the MAC address of each host in the EVI; publish the EVI-MAC route to the layer-3 gateway.
  • the layer-3 gateway will not receive the MAC address of the host in the layer-2 gateway. Effectively reduce the MAC routing pressure of the Layer 3 gateway. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the forwarding The above MAC forwarding table.
  • the EVI-MAC route also includes indication information, and the indication information instructs the layer-3 gateway to avoid sending the EVI-MAC route to the MAC forwarding table (forwarding table) of the forwarding plane after receiving the EVI-MAC route.
  • the MAC forwarding table records the mapping relationship between MAC addresses and outgoing interfaces.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the EVI-MAC route may also include an extended community attribute (extended community), and the extended community attribute is used to carry the aforementioned indication information.
  • the layer-3 gateway After receiving the EVI-MAC route, the layer-3 gateway avoids sending the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the extended community attribute of the EVI-MAC route (the extended community attribute carries the indication information) .
  • the indication information may be the extended community attribute, that is, the extended community attribute is used to instruct the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is an all-F MAC address.
  • the MAC address carried in the EVI-MAC route may be the MAC address of the Layer 2 gateway.
  • the MAC address carried in the EVI-MAC route may also be an all-F MAC address, and the all-F MAC address is also called a MAC address whose field value is all-F.
  • the field value of the MAC address of the route prefix in the MAC route is "0xfffffffffff". It can be understood that the MAC address carried in the EVI-MAC route may also be other field values, which is not limited here.
  • the Layer 2 gateway and the Layer 3 gateway are deployed in a campus network.
  • the campus network usually refers to the campus network of a university or the intranet of an enterprise.
  • Main features: The network devices (switches, routers, etc.) and transmission media (fiber optics, etc.) in the campus network are usually owned by the owner of the campus network, such as enterprise users, universities or government agencies.
  • the SRv6 technology can be successfully applied to a LAN network having a Layer 2 gateway and a Layer 3 gateway such as a campus network. This enables the campus network to be optimized for user traffic, improving network bandwidth utilization.
  • SRv6 technology has the advantage of being programmable, so it can effectively reduce the difficulty of implementing new services in the campus network.
  • the Layer 2 gateway performs packet forwarding for SRv6BE based on best-effort IPv6 segment routing.
  • the Layer 2 gateway forwards packets based on the IPv6 segment routing policy SRv6policy.
  • the embodiment of the present application proposes a communication method based on the segment routing SRv6 of the Internet protocol version 6, the method is executed by a layer-3 gateway, and the method includes: receiving an address resolution protocol ARP request from a layer-2 gateway message, the source Internet protocol SIP address of the ARP request message is the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the SRv6 SID applied for by the Ethernet virtual private network instance EVI at the two-layer gateway; according to the Described EVI SID obtains the corresponding relation of described EVI SID and outgoing interface, and described outgoing interface is used for sending the message that destination address is described EVI SID to described two-layer gateway by described three-layer gateway; Through described outgoing interface Send an ARP response message to the two-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • an EVPN neighbor is established between the Layer 2 gateway and the Layer 3 gateway through BGP.
  • BGP For the specific establishment process, please refer to the RFC7432 agreement, which will not be described here.
  • each EVI includes one or more hosts, and each EVI forms one or more cross-regional Layer 2 by connecting one or more groups of user networks network. Similar to the Layer 2 gateway, one or more EVIs are deployed (or applied for) in the Layer 3 gateway.
  • the SID applied for in the layer gateway is EVI SID-2.
  • the EVI SID is carried in the ARP request message sent by the second-layer gateway to the third-layer gateway, and the EVI SID is the SID of the EVI.
  • the layer-3 gateway determines the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway. Since the layer-2 gateway no longer sends the MAC address of the EVI host in the layer-2 gateway to the layer-3 gateway, the MAC routing pressure of the layer-3 gateway is effectively reduced. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the third-layer gateway obtains the corresponding outbound interface according to the EVI SID, and sends an ARP response message to the second-layer gateway through the outbound interface, thus ensuring that the ARP message between the second-layer gateway and the third-layer gateway can reach the destination smoothly, and the ARP The request process and the ARP reply process can be executed smoothly.
  • the three-layer gateway obtains the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, including: searching for forwarding information according to the EVI SID A table to obtain the corresponding relationship, wherein the forwarding table includes the corresponding relationship.
  • the layer-3 gateway searches the forwarding information table (forwarding information table) on the forwarding plane according to the EVI SID in the ARP request message to determine the outgoing interface.
  • the source of the forwarding information table is that the control plane of the layer-3 gateway learns the routing table and publishes it to the forwarding plane.
  • the forwarding information table is also called a forwarding table, or a forwarding information base (FIB).
  • the outbound interface is used by the Layer 3 gateway to send packets whose destination address is EVI SID to the Layer 2 gateway.
  • the specific content of the forwarding information table is similar to that of the routing table.
  • the forwarding information table can be understood as one or more sets of key-value pairs (key-value), and the three-layer gateway uses the EVI SID as a key to find the corresponding value in the forwarding information table, and the value is the outgoing interface .
  • the EVI SID is an end.dt2u type SID.
  • the SID of type end.dt2u has an endpoint "Endpoint with decapsulation and unicast MAC" for decapsulation and unicast MAC.
  • the SID of type end.dt2u is used for the EVPN Bridging Unicast use case "EVPN Bridging Unicast use case”.
  • the method further includes: receiving a media access control MAC route from the Layer 2 gateway, where the EVI-MAC route includes the EVI SID, The MAC address carried in the EVI-MAC route does not include the MAC address of each host in the EVI. Because the MAC address carried in the EVI-MAC route does not include the MAC addresses of the hosts in the EVI. Therefore, after the layer-2 gateway publishes the EVI-MAC route to the layer-3 gateway, the layer-3 gateway will not receive the MAC address of the host in the layer-2 gateway. Effectively reduce the MAC routing pressure of the Layer 3 gateway. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the EVI-MAC route includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the forwarding plane
  • the method further includes: according to the indication of the indication information, avoiding sending the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the EVI-MAC route also includes indication information, and the indication information instructs the layer-3 gateway to avoid sending the EVI-MAC route to the MAC forwarding table (forwarding table) of the forwarding plane after receiving the EVI-MAC route.
  • the MAC forwarding table records the mapping relationship between MAC addresses and outgoing interfaces.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is an all-F MAC address.
  • the MAC address carried in the EVI-MAC route may be the MAC address of the Layer 2 gateway.
  • the MAC address carried in the EVI-MAC route may also be an all-F MAC address, and the all-F MAC address is also called a MAC address whose field value is all-F.
  • the field value of the MAC address of the route prefix in the MAC route is "0xfffffffffff". It can be understood that the MAC address carried in the EVI-MAC route may also be other field values, which is not limited here.
  • the Layer 2 gateway and the Layer 3 gateway are deployed in a campus network.
  • the campus network usually refers to the campus network of a university or the intranet of an enterprise.
  • Main features: The network devices (switches, routers, etc.) and transmission media (fiber optics, etc.) in the campus network are usually owned by the owner of the campus network, such as enterprise users, universities or government agencies.
  • the SRv6 technology can be successfully applied to a LAN network having a Layer 2 gateway and a Layer 3 gateway such as a campus network. This enables the campus network to be optimized for user traffic, improving network bandwidth utilization.
  • SRv6 technology has the advantage of being programmable, so it can effectively reduce the difficulty of implementing new services in the campus network.
  • the Layer 2 gateway performs packet forwarding for SRv6BE based on best-effort IPv6 segment routing.
  • the Layer 2 gateway forwards packets based on the IPv6 segment routing policy SRv6policy.
  • the embodiment of the present application proposes a communication system, the communication system includes: a layer 2 gateway and a layer 3 gateway, and the communication system specifically includes:
  • the two-layer gateway generates the media access control EVI-MAC route based on the Ethernet virtual private network instance EVI, wherein the EVI-MAC route includes the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the EVI in the EVI
  • the SRv6 SID applied by the two-layer gateway, the MAC address carried in the EVI-MAC route does not include the MAC address of each host in the EVI;
  • the second-layer gateway publishes the EVI-MAC route to the third-layer gateway;
  • the three-layer gateway receives the media access control EVI-MAC route based on the Ethernet virtual private network instance notified by the two-layer gateway, and the EVI-MAC route includes the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the EVI In the SRv6 SID applied for by the two-layer gateway, the MAC address carried in the EVI-MAC route does not include the MAC addresses of each host in the EVI;
  • the layer-3 gateway obtains the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway .
  • the layer-3 gateway since the MAC address carried in the EVI-MAC route does not include the MAC addresses of the hosts in the EVI. Therefore, after the layer-2 gateway publishes the EVI-MAC route to the layer-3 gateway, the layer-3 gateway will not receive the MAC address of the host in the layer-2 gateway. Effectively reduce the MAC routing pressure of the Layer 3 gateway. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is an all-F MAC address.
  • the layer-3 gateway obtains the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, including: the layer-3 gateway searches for a route according to the EVI SID a table to obtain the corresponding relationship, wherein the routing table includes the corresponding relationship.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the forwarding The above MAC forwarding table.
  • the layer-3 gateway avoids delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the indication of the indication information.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the Layer 2 gateway sends an Address Resolution Protocol ARP request message to the Layer 3 gateway, and the source Internet Protocol SIP address of the ARP request message is The EVI SID;
  • the three-layer gateway determines to send an ARP response message to the two-layer gateway through the outbound interface according to the corresponding relationship between the EVI SID and the outgoing interface, and the destination Internet Protocol DIP address of the ARP response message is the described EVI SID;
  • the two-layer gateway receives the ARP response message sent by the three-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the EVI SID is an end.dt2u type SID.
  • the Layer 2 gateway and the Layer 3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding for SRv6BE based on best effort IPv6 segment routing.
  • the Layer 2 gateway forwards packets based on the IPv6 segment routing policy SRv6policy.
  • the embodiment of the present application proposes a communication system, the communication system includes: a layer-2 gateway and a layer-3 gateway, and the communication system specifically includes:
  • the two-layer gateway sends the Address Resolution Protocol ARP request message to the three-layer gateway, and the source Internet protocol SIP address of the ARP request message is the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the EVI SID in the two-layer gateway.
  • the two-layer gateway receives the ARP response message sent from the three-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID;
  • the three-layer gateway receives the address resolution protocol ARP request message from the two-layer gateway, and the source Internet Protocol SIP address of the ARP request message is an Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is an Ethernet virtual private network instance
  • the three-layer gateway obtains the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the three-layer gateway to send a message whose destination address is the EVI SID to the two-layer gateway;
  • the three-layer gateway sends an ARP response message to the two-layer gateway through the outgoing interface, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the layer-3 gateway since the MAC address carried in the EVI-MAC route does not include the MAC addresses of the hosts in the EVI. Therefore, after the layer-2 gateway publishes the EVI-MAC route to the layer-3 gateway, the layer-3 gateway will not receive the MAC address of the host in the layer-2 gateway. Effectively reduce the MAC routing pressure of the Layer 3 gateway. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the Layer 3 gateway After the Layer 3 gateway receives the EVI-MAC route, it determines that it needs to find the outgoing interface according to the EVI SID carried by the EVI-MAC route. The outbound interface is used by the Layer 3 gateway to send packets whose destination address is EVI SID to the Layer 2 gateway. On the premise that the layer-3 gateway does not use the MAC address of the host in the layer-2 gateway, the successful exchange of messages between the layer-2 gateway and the layer-3 gateway is still guaranteed.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • a forwarding information table is searched according to the EVI SID to obtain the corresponding relationship, where the forwarding table includes the corresponding relationship.
  • the EVI SID is an end.dt2u type SID.
  • the Layer 2 gateway generates an EVI-based media access control EVI-MAC route, where the EVI-MAC route includes the EVI SID, and the The MAC address carried in the EVI-MAC route does not include the MAC address of each host in the EVI;
  • the layer-2 gateway publishes the EVI-MAC route to the layer-3 gateway;
  • the three-layer gateway receives the media access control MAC route from the two-layer gateway, the EVI-MAC route includes the EVI SID, and the MAC address carried in the EVI-MAC route does not include the hosts in the EVI MAC address.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the forwarding plane.
  • MAC forwarding table
  • the layer-3 gateway avoids delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the indication of the indication information.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is an all-F MAC address.
  • the Layer 2 gateway and the Layer 3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding for SRv6BE based on best effort IPv6 segment routing.
  • the embodiment of the present application proposes a network device used as a Layer 2 gateway, including: a processing module and a transceiver module;
  • a processing module configured to generate a media access control EVI-MAC route based on an Ethernet virtual private network instance EVI, wherein the EVI-MAC route includes an Ethernet virtual private network instance segment identifier EVI SID, and the EVI SID is the EVI SID In the SRv6 SID applied for by the two-layer gateway, the MAC address carried in the EVI-MAC route does not include the MAC addresses of each host in the EVI;
  • a transceiver module configured to issue the EVI-MAC route to the layer-3 gateway.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the transceiver module is further configured to send an Address Resolution Protocol ARP request message to the layer-3 gateway, where the source Internet Protocol SIP address of the ARP request message is the EVI SID;
  • the transceiver module is also used to receive the ARP response message sent by the three-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the EVI SID is an end.dt2u type SID.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding based on best-effort SRv6BE of IPv6 segment routing.
  • the embodiment of the present application provides a network device, where the network device includes: a transceiver module and a processing module;
  • the transceiver module is used to receive the media access control EVI-MAC route based on the Ethernet virtual private network instance notified by the two-layer gateway, and the EVI-MAC route includes the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID It is the SRv6 SID applied for by the EVI at the layer-2 gateway, and the MAC address carried in the EVI-MAC route does not include the MAC addresses of each host in the EVI;
  • the processing module is used to obtain the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the three-layer gateway to send the destination address of the EVI SID to the two-layer gateway. message.
  • the processing module is further configured to search a routing table according to the EVI SID to obtain the corresponding relationship, where the routing table includes the corresponding relationship.
  • the processing module is further configured to avoid sending the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the indication of the indication information.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the transceiver module is further configured to receive an Address Resolution Protocol ARP request message from the Layer 2 gateway, and the source Internet Protocol SIP address of the ARP request message is the EVI SID ;
  • the processing module is also used for determining to send an ARP response message to the layer-2 gateway through the outbound interface according to the corresponding relationship between the EVI SID and the outbound interface, and the destination Internet protocol of the ARP outbound message
  • the DIP address is the EVI SID
  • the transceiver module is further configured to send the ARP response message to the Layer 2 gateway through the outbound interface.
  • the EVI SID is an end.dt2u type SID.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the layer-3 gateway is a centralized gateway for packet forwarding based on IPv6 segment routing best effort SRv6BE.
  • the embodiment of the present application provides a network device, where the network device includes: a transceiver module and a processing module;
  • the transceiver module is used to send the address resolution protocol ARP request message to the three-layer gateway, and the source Internet protocol SIP address of the ARP request message is an Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the The SRv6 SID applied for by the Ethernet virtual private network example EVI in the second-layer gateway in the second-layer gateway;
  • the transceiver module is also used to receive the ARP response message sent from the three-layer gateway, and the destination Internet protocol DIP address of the ARP response message is the EVI SID.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the EVI SID is an end.dt2u type SID.
  • the processing module is configured to generate an EVI-based media access control EVI-MAC route, wherein the EVI-MAC route includes the EVI SID, and the EVI-MAC The MAC address carried in the route does not include the MAC address of each host in the EVI;
  • the transceiver module is further configured to issue the EVI-MAC route to the layer-3 gateway.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding based on best-effort SRv6BE of IPv6 segment routing.
  • the embodiment of the present application proposes a network device used as a layer-3 gateway, the network device includes: a transceiver module and a processing module;
  • the transceiver module is used to receive the address resolution protocol ARP request message from the two-layer gateway, the source Internet protocol SIP address of the ARP request message is the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the Ethernet The SRv6 SID applied for by the virtual private network instance EVI at the layer-2 gateway;
  • the processing module is used to obtain the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the third-layer gateway to send the destination address to the second-layer gateway to be the EVI SID message;
  • the transceiver module is also used to send an ARP response message to the two-layer gateway through the outgoing interface, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the processing module is further configured to search a forwarding information table according to the EVI SID to obtain the corresponding relationship, wherein the forwarding table includes the corresponding relationship.
  • the EVI SID is an end.dt2u type SID.
  • the transceiver module is further configured to receive a media access control MAC route from the Layer 2 gateway, the EVI-MAC route includes the EVI SID, and the EVI-MAC route The MAC address carried in the EVI does not include the MAC address of each host in the EVI.
  • the processing module is further configured to avoid sending the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the indication of the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding based on best-effort SRv6BE of IPv6 segment routing.
  • the embodiment of the present application proposes a network device used as a Layer 2 gateway, including: a processor and a transceiver;
  • a processor configured to generate a media access control EVI-MAC route based on an Ethernet virtual private network instance EVI, wherein the EVI-MAC route includes an Ethernet virtual private network instance segment identifier EVI SID, and the EVI SID is the EVI SID In the SRv6 SID applied for by the two-layer gateway, the MAC address carried in the EVI-MAC route does not include the MAC addresses of each host in the EVI;
  • the transceiver is configured to issue the EVI-MAC route to the layer-3 gateway.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the transceiver is further configured to send an Address Resolution Protocol ARP request message to the layer-3 gateway, where the source Internet Protocol SIP address of the ARP request message is the EVI SID;
  • the transceiver is also used to receive the ARP response message sent by the three-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the EVI SID is an end.dt2u type SID.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding based on best-effort SRv6BE of IPv6 segment routing.
  • the embodiment of the present application proposes a network device used as a layer-3 gateway, where the network device includes: a transceiver and a processor;
  • the transceiver is used to receive the media access control EVI-MAC route based on the Ethernet virtual private network instance notified by the two-layer gateway, and the EVI-MAC route includes the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID It is the SRv6 SID applied for by the EVI at the layer-2 gateway, and the MAC address carried in the EVI-MAC route does not include the MAC addresses of each host in the EVI;
  • the processor is configured to obtain the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway. message.
  • the processor is further configured to search a routing table according to the EVI SID to obtain the corresponding relationship, where the routing table includes the corresponding relationship.
  • the processor is further configured to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the indication of the indication information.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the transceiver is further configured to receive an Address Resolution Protocol ARP request message from the Layer 2 gateway, where the source Internet Protocol SIP address of the ARP request message is the EVI SID ;
  • the processor is further configured to determine, according to the correspondence between the EVI SID and the outgoing interface, to send an ARP response message to the Layer 2 gateway through the outgoing interface, and the destination Internet protocol of the ARP response message
  • the DIP address is the EVI SID
  • the transceiver is further configured to send the ARP response message to the Layer 2 gateway through the outbound interface.
  • the EVI SID is an end.dt2u type SID.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the layer-3 gateway is a centralized gateway for packet forwarding based on IPv6 segment routing best effort SRv6BE.
  • the embodiment of the present application provides a network device used as a Layer 2 gateway, where the network device includes: a transceiver and a processor;
  • Described transceiver is used for sending address resolution protocol ARP request message to three-layer gateway, and the source internet protocol SIP address of described ARP request message is the ether virtual private network instance segment identification EVI SID, and described EVI SID is described
  • the transceiver is also used to receive the ARP response message sent from the three-layer gateway, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the layer-2 gateway disables a function of publishing the host MAC route in the EVI to the layer-3 gateway.
  • the EVI SID is an end.dt2u type SID.
  • the processor is configured to generate an EVI-based media access control EVI-MAC route, where the EVI-MAC route includes the EVI SID, and the EVI-MAC The MAC address carried in the route does not include the MAC address of each host in the EVI;
  • the transceiver is further configured to issue the EVI-MAC route to the layer-3 gateway.
  • the EVI-MAC route further includes indication information, and the indication information instructs the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • the EVI-MAC route includes an extended community attribute, and the extended community attribute is used to bear the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the Layer 2 gateway performs packet forwarding based on best-effort SRv6BE of IPv6 segment routing.
  • the embodiment of the present application proposes a network device used as a layer-3 gateway, where the network device includes: a transceiver and a processor;
  • the transceiver is used to receive the address resolution protocol ARP request message from the two-layer gateway, the source Internet Protocol SIP address of the ARP request message is the Ethernet virtual private network instance segment identification EVI SID, and the EVI SID is the Ethernet The SRv6 SID applied for by the virtual private network instance EVI at the layer-2 gateway;
  • the processor is configured to obtain the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send the destination address to the layer-2 gateway as the EVI SID message;
  • the transceiver is also used to send an ARP response message to the Layer 2 gateway through the outgoing interface, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the processor is further configured to search a forwarding information table according to the EVI SID to obtain the corresponding relationship, where the forwarding table includes the corresponding relationship.
  • the EVI SID is an end.dt2u type SID.
  • the transceiver is further configured to receive a media access control MAC route from the Layer 2 gateway, the EVI-MAC route includes the EVI SID, and the EVI-MAC route The MAC address carried in the EVI does not include the MAC address of each host in the EVI.
  • the processor is further configured to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the indication of the indication information.
  • the MAC address carried in the EVI-MAC route is the MAC address of the Layer 2 gateway, or is a full-F MAC address.
  • the layer-2 gateway and the layer-3 gateway are deployed in a campus network.
  • the layer-2 gateway performs packet forwarding based on best-effort SRv6BE of IPv6 segment routing.
  • a fifteenth aspect provides a communication system, characterized in that the communication system includes the network device according to the seventh aspect or the eighth aspect.
  • a sixteenth aspect provides a communication system, characterized in that the communication system includes the network device according to the ninth aspect or the tenth aspect.
  • a seventeenth aspect provides a communication system, characterized in that the communication system includes the network device according to the eleventh aspect or the twelfth aspect.
  • An eighteenth aspect provides a communication system, characterized in that the communication system includes the network device as described in the thirteenth aspect or the fourteenth aspect.
  • a nineteenth aspect of the present application provides a computer storage medium, which may be non-volatile; computer-readable instructions are stored in the computer storage medium, and when the computer-readable instructions are executed by a processor, the first A method in any implementation manner of the aspect, the second aspect, the third aspect, or the fourth aspect.
  • the twentieth aspect of the present application provides a computer program product containing instructions, which, when run on a computer, causes the computer to execute any of the implementations in the first aspect, the second aspect, the third aspect, or the fourth aspect. Methods.
  • the twenty-first aspect of the present application provides a chip system
  • the chip system includes a processor, configured to support the network device to implement the functions involved in the above aspect, for example, send or process the data and/or information involved in the above method .
  • the chip system further includes a memory, and the memory is used for storing necessary program instructions and data of the network device.
  • the system-on-a-chip may consist of chips, or may include chips and other discrete devices.
  • Figure 1a is a schematic diagram of a centralized gateway
  • Figure 1b is a schematic diagram of a centralized gateway under the VXLAN architecture
  • Figure 2a is a schematic flow chart of the ARP request process
  • Figure 2b is a schematic flow chart of the ARP response process
  • FIG. 3a is a schematic diagram of an embodiment of an SRv6-based communication method 30 proposed in an embodiment of the present application
  • FIG. 3b is a schematic diagram of ARP packet interaction in the embodiment of the present application.
  • FIG. 3c is a schematic structural diagram of an ARP request message or an ARP response message in an embodiment of the present application
  • FIG. 3d is a schematic structural diagram of an SRv6BE message in the embodiment of the present application.
  • FIG. 4 is a schematic diagram of an embodiment of an SRv6-based communication method 40 proposed in an embodiment of the present application
  • FIG. 5 is a schematic diagram of an embodiment of an SRv6-based communication method 50 proposed in an embodiment of the present application
  • FIG. 6 is a schematic diagram of an extended community attribute proposed by an embodiment of the present application.
  • FIG. 7 is a schematic diagram of an application scenario proposed by an embodiment of the present application.
  • FIG. 8 is a schematic structural diagram of a network device 800 provided in an embodiment of the present application.
  • FIG. 9 is a schematic structural diagram of a network device 900 provided in an embodiment of the present application.
  • FIG. 10 is a schematic structural diagram of a network device 1000 provided in an embodiment of the present application.
  • FIG. 11 is a schematic diagram of a network system 1100 proposed by an embodiment of the present application.
  • FIG. 12 is a schematic diagram of a network system 1200 proposed by an embodiment of the present application.
  • the naming or numbering of the steps in this application does not mean that the steps in the method flow must be executed in the time/logic sequence indicated by the naming or numbering.
  • the execution order of the technical purpose is changed, as long as the same or similar technical effect can be achieved.
  • the division of units presented in this application is a logical division. In actual application, there may be other division methods. For example, multiple units can be combined or integrated in another system, or some features can be ignored. , or not, in addition, the shown or discussed mutual coupling or direct coupling or communication connection may be through some interfaces, and the indirect coupling or communication connection between units may be electrical or other similar forms, this Applications are not limited.
  • the units or subunits described as separate components may or may not be physically separated, may or may not be physical units, or may be distributed into multiple circuit units, and some or all of them may be selected according to actual needs unit to realize the purpose of the application scheme.
  • Segment routing It is a protocol designed based on the concept of source routing to forward data packets in the network. SR divides the network path into segments, and assigns segment identifiers (segment id, SID) to these segments and network nodes. By arranging the SIDs in an orderly manner, a segment list (SID List, also known as SID in SR-MPLS) can be obtained. Called label stack), SID List can indicate a forwarding path.
  • SID List also known as SID in SR-MPLS
  • SID List can indicate a forwarding path.
  • the head node will add a label stack to the data packet, and the intermediate node can forward it to the next node according to the label stack until the data packet reaches the destination node.
  • the data packet will first be forwarded to the node corresponding to SID1, then to the node corresponding to SID2, and then to the node corresponding to SID3.
  • the full name of SR-MPLS in Chinese and English is segment routing multi-protocol label switching (segment routing multi-protocol label switching).
  • Segment routing based on Internet Protocol Version 6 (IPv6): refers to the application of SR technology in IPv6 networks. Use IPv6 address (128bits) as the representation of SID.
  • IPv6 address (128bits) as the representation of SID.
  • the data packet can be forwarded from the outgoing interface corresponding to the SID; if the data packet If there is no longest match between the destination address and each SID in the local segment identification table, the IPv6 forwarding table is checked again, and the longest matching forwarding is performed according to the IPv6 forwarding table.
  • SR policy is a traffic engineering mechanism of SR.
  • an SR Policy includes a headend node (headend), a color identifier (color) and an endpoint (endpoint), as well as a segment identifier list indicating a forwarding path.
  • Headend is used to identify the head node that executes SR Policy
  • Color is used to associate SR with business attributes, such as low latency, high bandwidth and other business attributes, to summarize the service capabilities of the SR Policy
  • Endpoint is used to identify Destination address of SR Policy.
  • an SR Policy is determined by (headend, color, endpoint).
  • an SR Policy can also be determined by (color, endpoint).
  • SR policy can include one or more segment identification lists to achieve load balancing, multi-path backup and other functions.
  • the head node can determine the segment identification list corresponding to the message according to the SR policy, so as to determine the forwarding path for forwarding the message, and encapsulate the segment identification list into the message to indicate the candidate of the message path, the candidate path includes a display candidate path and a dynamic candidate path.
  • SRv6 In SRv6 technology, only one service SID can be used to instruct packets to perform best-effort forwarding on the IP network. This technology is called SRv6BE.
  • the segment routing header (segment routing header, SRH) is not encapsulated in the SRv6BE message.
  • Virtual extended local area network (virtual extensible LAN, VXLAN):
  • VXLAN is a network virtualization technology widely used in large Layer 2 networks.
  • a logical VXLAN tunnel is established between the source network device and the destination network device, and the media access control (media access control, MAC) address is encapsulated in the user datagram protocol (user datagram protocol, UDP) encapsulation method, that is, the virtual
  • UDP user datagram protocol
  • the original Ethernet packet sent by the machine is completely encapsulated in the UDP packet, and then encapsulated in the outer layer using the IP packet header and the Ethernet packet header of the physical network.
  • the encapsulated packet is just like a normal IP packet and can be Through routing network forwarding, the virtual machine can completely get rid of the structural restrictions of the second and third layers of the network.
  • Layer 2 gateway (layer2 gateway, L2GW) and layer 3 gateway (layer3 gateway, L3GW):
  • a gateway that provides network services for Layer 2 services is called a Layer 2 gateway, and a gateway that provides network services for Layer 3 services is called a Layer 3 gateway.
  • Layer 2 services refer to services at the data link layer.
  • Layer 3 services refer to services at the network layer.
  • the data link layer is the second layer of the open system interconnection (OSI) model
  • the network layer is the third layer of the OSID model.
  • Figure 1a is a schematic diagram of a centralized gateway.
  • Figure 1a includes a layer-3 gateway (L3GW) and two layer-2 gateways, wherein the layer-2 gateway includes a layer-2 gateway as an edge (edge) 1 node and a layer-2 gateway as an edge 2 node, and the layer-3 gateway as a boundary ( border) node.
  • EVI1 and EVI2 are provided in the Layer 3 gateway. Multiple isolated EVIs can be configured on one physical device. Each EVI connects one or more groups of user networks. Multiple edge nodes form one or more cross-regional Layer 2 networks.
  • host 1_11, host 1_12, and host 2_11 form a cross-region Layer 2 network, and the geographical locations of the hosts in the Layer 2 network are different.
  • EVI1 includes host 1_11 and host 1_12
  • EVI2 includes host 2_11 and host 2_12.
  • VXLAN gateways are divided into two-layer gateways and three-layer gateways.
  • VXLAN two-layer gateways are used for terminals to access the VXLAN network, and can also be used for subnet communication in the same VXLAN network;
  • VXLAN three-layer gateways are used for inter-subnet communication and access in the VXLAN network External network.
  • VXLAN Layer 3 gateways can be divided into centralized gateways and distributed gateways.
  • NVO3 network virtualization layer 3
  • NVE network virtualization edge
  • VTEP VXLAN tunnel endpoint
  • VTEP VXlan tunnel endpoint
  • Figure 1b is a schematic diagram of a centralized gateway under the VXLAN architecture.
  • host 1_12 and host 2_11 are in the same subnet, and the traffic between the two does not need to pass through the L3GW, but can be directly forwarded at Layer 2 between the L2GWs, and the media access control (media access control, MAC) routing.
  • the host 1_11 and the host 2_21 cross subnets, and the traffic between the two needs to be forwarded through the L3GW layer 3.
  • the data sent from the L3GW to the L2GW needs to be guided by the address resolution protocol (ARP) information of the host.
  • ARP address resolution protocol
  • the ARP protocol is a protocol used to resolve Internet Protocol (IP) addresses into MAC addresses.
  • IP Internet Protocol
  • a network device or host
  • IP address network layer address
  • the sender must also have the receiver's physical address (MAC address), so a link from the IP address to the physical address is required map.
  • ARP is the protocol to achieve this function. Specifically, the address resolution is completed through the ARP request process and the ARP response process.
  • FIG. 2a is a schematic flowchart of the ARP request process.
  • Host A and HOSTB are on the same network segment, and HOSTA wants to send information to HOSTB.
  • HOSTA checks its own ARP table to determine whether there is an ARP entry corresponding to HOSTB. If the MAC address corresponding to HOSTB is found, then HOSTA directly utilizes the MAC address in the ARP table to perform frame encapsulation on the IP data packet, and sends the data packet to HOSTB. If HOSTA cannot find the corresponding MAC address in the ARP table, it will buffer the data packet and then send an ARP request packet in broadcast mode.
  • the sender IP address and sender MAC address in the ARP request message are the IP address and MAC address of HOSTA, the target IP address is the IP address of HOSTB, and the target MAC address is the MAC address of all 0s. Since the ARP request message is sent in broadcast mode, all hosts on the network segment can receive the request, but only the requested host (that is, HOSTB) will process the request.
  • FIG. 2b is a schematic flowchart of the ARP response process.
  • HOSTB compares its own IP address and the target IP address in the ARP request message, and when the two are the same, proceed as follows: store the IP address and the MAC address of the sender (ie HOSTA) in the ARP request message into its own ARP table. Then send an ARP response message to HOSTA in unicast mode, which contains its own MAC address.
  • HOSTB sends an ARP response message containing its MAC address to HOSTA. After HOSTA receives the ARP response message, it adds the MAC address of HOSTB into its own ARP table for subsequent message forwarding, and at the same time encapsulates the IP data packet and sends it out.
  • a campus network usually refers to a university's campus network or an enterprise's intranet.
  • VXLAN technology found that it is difficult to expand new services in the campus network using VXLAN technology.
  • packet forwarding in a network using VXLAN technology is based on IP routing, the campus network using VXLAN technology cannot be optimized for user traffic.
  • the embodiment of the present application proposes applying the SRv6 technology to a campus network as an example of a local area network. Because the SRv6 technology is programmable, it can improve the service expansion capability of the campus network and reduce the difficulty of implementing new services on the campus network. In addition, the campus network using SRv6 technology can also be optimized for user traffic to make full use of network bandwidth resources.
  • FIG. 3a is a schematic diagram of an embodiment of an SRv6-based communication method 30 proposed in an embodiment of the present application.
  • the SRv6-based communication method 30 can be applied to the network architecture shown in FIG. 1a. Specifically, communication and interaction between the layer-2 gateway and the layer-3 gateway are implemented based on SRv6. The forwarding of packets is guided by EVPN type3 routing and EVPN type2 routing between the Layer 2 gateway and Layer 3 gateway. Packets exchanged between Layer 2 gateways and Layer 3 gateways carry SRv6 headers.
  • SRv6 technology such as campus networks have traffic engineering capabilities. Specific instructions are given below:
  • the EVI of the layer-2 gateway publishes the EVPN type3 route to the layer-3 gateway.
  • step 301 a scenario in which EVPN instances are respectively deployed on a Layer 2 gateway and a Layer 3 gateway is used as an example for illustration.
  • a border gateway protocol border gateway protocol, BGP
  • BGP border gateway protocol
  • the BGP neighbor relationship is also called the BGP peer (BGP peer) relationship.
  • BGP peer relationship between A and B means: A is B's BGP peer, and B is A's BGP peer.
  • RFC request for comments
  • each EVI includes one or more hosts, and each EVI connects one or more groups of user networks, Constitute one or more cross-regional Layer 2 networks. Similar to the Layer 2 gateway, one or more EVIs are deployed (or applied for) in the Layer 3 gateway.
  • EVI Ethernet virtual private network examples
  • the EVI of the Layer 2 gateway publishes (or advertises) the EVPN type3 route, also known as the integrated multicast route (inclusive multicast route), and the EVPN type3 route is used to guide the forwarding of broadcast&unknown-unicast&multicast (broadcast&unknown-unicast&multicast, BUM) traffic .
  • the EVPN type3 route also known as the integrated multicast route (inclusive multicast route)
  • BUM broadcast&unknown-unicast&multicast
  • each field of the EVPN type3 route advertised by the EVI of the Layer 2 gateway is shown in Table 1:
  • Ethernet Tag ID and Originating Router's IP Address are used as prefix indexes.
  • BGP Prefix-SID BGP Prefix Segment Identifier
  • a SID of type end.dt2m has an Endpoint with decapsulation and L2 representation "Endpoint with decapsulation and L2 table.
  • a SID of type end.dt2m is used for the use case of Unicast or Multicast (BUM)" Unicast and Multicast (BUM )use case with” or "Ethernet Segment Identifier (ESI) filtering".
  • the EVI of the layer-3 gateway publishes the EVPN type3 route to the layer-2 gateway.
  • the EVPN type3 route published by the layer-3 gateway is similar to the EVPN type3 route published by the layer-2 gateway in step 301.
  • the BGP Prefix-SID attribute of the EVPN type3 route carries the SID applied by EVI at the layer-3 gateway.
  • the SID is a SID of type end.dt2m.
  • the layer-2 gateway publishes the EVPN type2 route to the layer-3 gateway.
  • the Layer 2 gateway advertises the MAC address to the Layer 3 gateway through EVPN EVPN type2 routing.
  • the host is a host in the EVI deployed in the Layer 2 gateway.
  • EVPN type2 routing also known as MAC/IP advertisement route (MAC/IP advertisement route)
  • MAC/IP advertisement route is used to advertise the host's MAC address or MAC+ address and IP address information.
  • the Layer 3 gateway After receiving the EVPN type2 route, the Layer 3 gateway generates a MAC forwarding table. This EVPN type2 route is used to guide unicast traffic forwarding.
  • each field of the EVPN type2 route is shown in Table 2:
  • Ethernet segment identifier 10octets Ethernet Tag ID 4octets MAC Address Length 1 octet MAC Address 6octets IP Address Length 1 octet IP address (IP Address) 4 or 16octets Multiprotocol Label Switching Label (MPLS Label) 3octets Multiprotocol Label Switching Label 2 (MPLS Label) 0 or 3octets
  • the prefix index includes: Ethernet Tag ID, MAC Address, IP Address. ESI and MPLS Label are used as routing attributes.
  • the BGP Prefix-SID attribute carries the SID applied by EVI at the Layer 2 gateway, which is the SID of the end.dt2u type.
  • a SID of type end.dt2u has an endpoint "Endpoint with decapsulation and unicast MAC" with decapsulation and unicast MAC.
  • the SID of type end.dt2u is used for the EVPN Bridging Unicast use case "EVPN Bridging Unicast use case".
  • the Layer 3 gateway After the Layer 3 gateway receives the EVPN type2 route, the unicast traffic between the Layer 3 gateway and the Layer 2 gateway is reachable.
  • steps 301-302 and step 303 are not limited here, either steps 301-302 may be executed first, and then step 303 may be executed; or step 303 may be executed first, and then steps 301-302 may be executed.
  • the layer-2 gateway sends an ARP request packet to the layer-3 gateway.
  • step 304 the layer-2 gateway sends an APR request message to the layer-3 gateway.
  • FIG. 3b is a schematic diagram of ARP message interaction in this embodiment of the application.
  • the hosts in the layer 2 gateway include host 1_11 and host 1_12 as an example for illustration.
  • the host 1_11 generates an ARP request message and sends the ARP request message to the second-layer gateway.
  • the ARP request message sent by the host to the second-layer gateway is called the first ARP request message. arts.
  • FIG. 3c is a schematic structural diagram of an ARP request message or an ARP response message in this embodiment of the present application.
  • the ARP request message includes the following fields: destination MAC address (DMAC), source MAC address (SMAC), frame type, ARP request or ARP response.
  • DMAC destination MAC address
  • SMAC source MAC address
  • the ARP request or ARP response field includes the following fields: destination MAC address, source MAC address, frame type, MAC address type, IP protocol type, MAC address length, IP address length, OP, sender MAC address, sender IP address, destination MAC address, and destination IP address.
  • DMAC destination MAC address
  • SMAC source MAC address
  • frame type ARP request or ARP response
  • the ARP request or ARP response field includes the following fields: destination MAC address, source MAC address, frame type, MAC address type, IP protocol type, MAC address length, IP address length, OP, sender MAC address, sender IP address, destination MAC address, and destination IP address.
  • Destination MAC address 6 bytes in length.
  • the destination MAC address is a broadcast MAC address (0xFF.FF.FF.FF.FF.FF).
  • Source MAC address 6 bytes in length.
  • Frame type 2 bytes long, the value of this field is 0x0806.
  • MAC address type 2 bytes in length, which defines the address type of the ARP network.
  • a value of 1 means an Ethernet address.
  • IP protocol type 2 bytes long, defining the type of protocol. The value is 0x0800, which means the IP address.
  • MAC address length 1 byte length, which defines the length of the physical address in bytes. For ARP request packets or ARP response packets, the value is 6.
  • IP address length 1 byte length, which defines the length of the logical address in bytes. For ARP request packets or ARP response packets, the value is 4.
  • OP field 2 bytes in length, defining the type of ARP packet.
  • the packet is an ARP request packet; when the value of the OP field is 2, the packet is an ARP response packet.
  • Sender MAC address 6 bytes in length, defining the MAC address of the sending station.
  • Sender IP address 4 bytes in length, defining the IP address of the sending station.
  • Destination MAC address 6 bytes in length. When the packet is an ARP request packet, the value of this field is 0.
  • the layer-2 gateway encapsulates the SEV6 message header based on the first ARP request message to generate a second ARP request message.
  • the message payload (payload) of the second ARP request message is the first ARP request message.
  • the second ARP request packet can be understood as an SRv6 packet. Exemplarily, the following takes the second ARP request packet as an SRv6BE packet as an example for illustration, please refer to FIG. 3d , which is a schematic structural diagram of an SRv6BE packet in the embodiment of the present application.
  • the SEV6BE message includes the following fields: version (version), traffic class (traffic class), flow label (flow label), payload length (payload length), next header (next header), maximum hop count (hop limit) , source address (source address) and destination address (destination address).
  • the version (version) field indicates the IP version of the SEV6BE message, and the value of this field is 6;
  • the traffic class (traffic class) field is similar to the service type (TOS) field of the IPV4 packet header;
  • the flow label (flow label) is used to mark IPV6 A stream of data packets;
  • the next header (next header) field, the field value is 143;
  • the maximum hop limit (hop limit) field defines the maximum number of hops that an IP data packet can pass through, and the value of this field is reduced by 1 for each hop;
  • the source address (source address) field is the source address of the IP data packet;
  • the destination address (destination address) is the destination address of the IP data packet.
  • the field value of the destination address field in the second ARP request message is a sid of type end.dt2m issued by the layer-3 gateway.
  • the field value of the destination address field in the second ARP response message is the sid of type end.dt2u issued by the Layer 2 gateway.
  • the destination address field in the second ARP request message can also be understood as the destination address field in the SRv6 packet header of the second ARP request message; the destination address field in the second ARP response message can also be understood as the first 2.
  • the destination address field in the SRv6 packet header of the ARP response packet can also be understood as the first 2.
  • the layer-3 gateway sends an ARP response message to the layer-2 gateway.
  • step 305 after receiving the second ARP request message from the second layer gateway, the layer-3 gateway strips off the SRv6 header of the second ARP request message to obtain the first ARP request message. Then, the layer-3 gateway sends the first ARP request packet to the control plane for ARP learning.
  • the layer-3 gateway sends an ARP response message to the layer-2 gateway.
  • the ARP response message sent by the layer-3 gateway to the layer-2 gateway is called the first ARP response message.
  • the first ARP response message is obtained by the layer-3 gateway after encapsulating the SRv6 message header based on the second ARP response message, and the second ARP response message is used as a payload of the first ARP response message.
  • the layer-2 gateway After receiving the first ARP response message from the layer-3 gateway, the layer-2 gateway strips off the SRv6 message header to obtain the second ARP response message. Then, the layer-2 gateway sends the second ARP response message to the host 1_11. After receiving the second ARP response message, the host 1_11 performs ARP learning.
  • the process of establishing message transmission between the layer 2 gateway and the layer 3 gateway is completed.
  • Data packets can be exchanged between the Layer 2 gateway and the Layer 3 gateway, and the data packets carry SRv6 packet headers.
  • the SRv6 packet header in the data packet is similar to the SRv6 packet header of the ARP packet (including the ARP request packet and the ARP response packet), and details are not described here.
  • traffic optimization can be implemented through various means, which are described below with examples. It can be understood that the means of traffic optimization are not limited in this embodiment of the present application.
  • the campus network also includes a controller.
  • the Layer 2 gateway and the Layer 3 gateway detect the path delay through the Two-Way Active Measurement Protocol (TWAMP), and report the detection result (ie, the path delay) to the controller.
  • the controller calculates a path satisfying a service level agreement (service level agreement, SLA) based on the detection result (ie, path delay), and determines SRv6 path information of the path.
  • the controller sends the SRv6 path information of the path to the Layer 2 gateway or the Layer 3 gateway.
  • service level agreement service level agreement
  • the Layer 2 gateway or Layer 3 gateway imports the SRv6 path information of the path into the SRv6 policy (policy), and forwards the message according to the path calculated by the controller to meet the SLA requirements.
  • Layer 2 gateways and/or Layer 3 gateways use TWAMP to detect path delay and report to the controller through telemetry (Telemetry) technology. When the controller finds that the time domain of the path The path meets the SLA requirements.
  • the SRv6 technology can be successfully applied to the campus network and other LAN networks with Layer 2 gateways and Layer 3 gateways.
  • This enables the campus network to be optimized for user traffic, improving network bandwidth utilization.
  • SRv6 technology has the advantage of being programmable, so it can effectively reduce the difficulty of implementing new services in the campus network.
  • the campus network has traffic engineering capabilities, so it can effectively balance the services of each gateway in the campus network and avoid wasting network bandwidth.
  • Traffic engineering means that network nodes can establish data forwarding paths based on effective resources in the network, and have the ability to reserve network bandwidth for critical traffic. Through dynamic monitoring of network traffic and network element load, real-time adjustment of traffic management parameters, routing parameters and resource constraint parameters, etc., optimize the use of network resources and avoid congestion caused by uneven load.
  • the layer 3 gateway (layer3 gateway, L3GW) needs to store and manage the media access control (media access control, MAC) of each host
  • These hosts are hosts under the jurisdiction of all layer 2 gateways (layer2 gateway, L2GW) that have communication connections with the layer 3 gateway.
  • layer3 gateway Layer2 gateway, L2GW
  • MAC media access control
  • the MAC address of the host is no longer stored in the layer-3 gateway, and the layer-3 gateway can obtain the outgoing interface through various means, and the outgoing interface is used to indicate the A path for the layer-3 gateway to send the response message to the layer-2 gateway.
  • the MAC routing pressure of the layer-3 gateway can be effectively reduced, and network expansion can be realized at a lower cost.
  • FIG. 4 or FIG. 5 may support the SRv6BE technology or the SRv6policy technology, which is not limited here.
  • the Layer 3 gateway can obtain the outbound interface through the control plane, and the Layer 3 gateway can also obtain the outbound interface through the forwarding plane.
  • the Layer 3 gateway obtains the outbound interface through the control plane.
  • FIG. 4 is a schematic diagram of an embodiment of an SRv6-based communication method 40 proposed in an embodiment of the present application.
  • An SRv6-based communication method 40 proposed in the embodiment of the present application includes:
  • the layer-2 gateway disables the function of publishing the host MAC route in the EVI.
  • the Layer 2 gateway closes publishing the MAC route of the host in the EVI to the Layer 3 gateway, and the host is a host in an Ethernet virtual private network instance (EVPN instance, EVI) deployed (or configured) in the Layer 2 gateway. For example the host in EVI.
  • EVI Ethernet virtual private network instance
  • the Layer 2 gateway advertises the host MAC routes in the EVI to the Layer 3 gateway.
  • the MAC route generated by the Layer 2 gateway does not include the MAC address of the host, and the destination of the MAC route is the Layer 3 gateway.
  • the layer-3 gateway will not receive the MAC address of each host in the layer-2 gateway, thereby preventing the layer-3 gateway from saving the MAC address of the host and reducing the MAC address of the layer-3 gateway Routing stress.
  • the Layer 2 gateway can also be configured so as not to send the MAC address of the host to the Layer 3 gateway, which is not limited here.
  • step 400 is an optional step.
  • the layer-2 gateway may issue a MAC route to the layer-3 gateway, where the MAC route includes the MAC addresses of the hosts in the EVI.
  • the layer-3 gateway does not save the MAC addresses of the hosts in the EVI.
  • the layer-2 gateway generates an EVI-MAC route.
  • step 401 first, an Ethernet virtual private network (ethernet virtual private network, EVPN) neighbor is established between the second-layer gateway and the third-layer gateway through the border gateway protocol (border gateway protocol, BGP).
  • border gateway protocol border gateway protocol, BGP.
  • an example of an Ethernet virtual private network included in a Layer 2 gateway is taken as an example, and the EVI includes one or more hosts. It can be understood that the Layer 2 gateway may also include multiple EVIs, which is not limited here.
  • the layer-2 gateway After the layer-2 gateway establishes an EVPN neighbor relationship with the layer-3 gateway, the layer-2 gateway generates a MAC route, and the MAC route includes a segment identifier (segment identifier, SID) applied for by the EVI at the layer-2 gateway.
  • SID segment identifier
  • the SID of the EVI application is referred to as the EVI SID.
  • the EVI SID is a SID of type end.dt2u. This MAC routing is called EVI-MAC routing.
  • the type of the EVI-MAC route is an EVPN type2 route.
  • the SID applied for in the layer gateway is EVI SID-2.
  • FIG. 7 is a schematic diagram of an application scenario proposed by the embodiment of the present application.
  • An SRv6 tunnel is established between the Layer 2 gateway and the Layer 3 gateway, and an SRv6 tunnel is established between the edge1 node and the edge2 node.
  • Layer 3 gateways include EVI1 and EVI2. Then the SID applied for by EVI1 at the edge1 node is inconsistent with the SID applied for by EVI1 at the edge2 node.
  • the MAC address carried in the EVI-MAC route does not include the MAC addresses of the hosts in the EVI.
  • the MAC address carried in the EVI-MAC route may be the MAC address of the Layer 2 gateway.
  • the MAC address carried in the EVI-MAC route may also be an all-F MAC address, and the all-F MAC address is also called a MAC address whose field value is all-F.
  • the field value of the MAC address of the route prefix in the MAC route is "0xfffffffffff". It can be understood that the MAC address carried in the EVI-MAC route may also be other field values, which is not limited here.
  • the EVI-MAC route also includes indication information, and the indication information indicates that after the layer-3 gateway receives the EVI-MAC route, avoid sending the EVI-MAC route to the MAC forwarding table (forwarding table) of the forwarding plane .
  • the MAC forwarding table records the mapping relationship between MAC addresses and outgoing interfaces.
  • the EVI-MAC route may also include an extended community attribute (extended community), and the extended community attribute is used to carry the aforementioned indication information.
  • the layer-3 gateway After receiving the EVI-MAC route, the layer-3 gateway avoids sending the EVI-MAC route to the MAC forwarding table of the forwarding plane according to the extended community attribute of the EVI-MAC route (the extended community attribute carries the indication information) .
  • the indication information may be the extended community attribute, that is, the extended community attribute is used to instruct the layer-3 gateway to avoid delivering the EVI-MAC route to the MAC forwarding table of the forwarding plane.
  • FIG. 6 is a schematic diagram of an extended community attribute proposed in an embodiment of the present application.
  • EVI-MAC routing is shown in Table 3:
  • the layer-2 gateway advertises the EVI-MAC route to the layer-3 gateway.
  • step 402 after the Layer 2 gateway generates the EVI-MAC route, the Layer 2 gateway publishes the EVI-MAC route to the Layer 3 gateway. Specifically, the layer-2 gateway advertises the EVI-MAC route to the layer-3 gateway through an IP message.
  • the layer-3 gateway determines the outgoing interface according to the EVI SID in the EVI-MAC route.
  • step 403 after the three-layer gateway receives the EVI-MAC route, according to the MAC address carried by the EVI-MAC route (this MAC address is the MAC address of the two-layer gateway, or, is the MAC address of the full F), it is determined that the The EVI SID carried by the EVI-MAC route looks up the outgoing interface.
  • the outbound interface is used by the Layer 3 gateway to send packets whose destination address is EVI SID to the Layer 2 gateway.
  • the layer-3 gateway can also determine the need to find the outgoing interface according to the EVI SID carried by the EVI-MAC route according to the extended community attribute included in the EVI-MAC route, and there is no limitation here.
  • the layer-3 gateway searches the routing table (routing table) on the forwarding plane to determine the outgoing interface.
  • the routing table is also called routing information table (routing information table) or routing information base (routing information base, RIB).
  • the routing table can be understood as one or more sets of key-value pairs (key-value), and the layer-3 gateway uses the EVI SID as a key to search for the corresponding value in the routing table, which is the outgoing interface.
  • FIG. 7 is a schematic diagram of an application scenario proposed by the embodiment of the present application.
  • the Layer 2 gateway includes edge1 and edge2 nodes, where the edge1 node includes EVI1, and the edge2 node includes EVI1 and EVI2.
  • An SRv6 tunnel is established between the Layer 2 gateway and the Layer 3 gateway, and an SRv6 tunnel is established between the edge1 node and the edge2 node.
  • Layer 3 gateways include EVI1 and EVI2.
  • the layer-3 gateway looks up the routing table (such as the example in Table 4) according to the EVI SID as the DIP, and determines that the outgoing interface is "0001". Exemplarily, the layer-3 gateway determines the path of the ARP response message according to the outgoing interface.
  • the layer-2 gateway sends an ARP request packet to the layer-3 gateway.
  • the two-layer gateway receives the ARP request message of the host of the EVI in the two-layer gateway.
  • the ARP request message sent by the host to the two-layer gateway is called the first ARP request message .
  • the Layer 2 gateway (edge1 node) receives the first ARP request message from the host 1_11.
  • the Layer 2 gateway encapsulates the SRv6 packet header based on the first ARP request packet from the host 1_11, and obtains the ARP request packet carrying the SRv6 packet header.
  • the ARP request packet carrying the SRv6 packet header is called It is the second ARP request packet.
  • the SIP in the SRv6 packet header is the EVI SID.
  • the DIP of the second ARP request message is the SID of the layer-3 gateway.
  • the SID of the layer-3 gateway is issued by the layer-3 gateway when the layer-2 gateway establishes an EVPN neighbor relationship with the layer-3 gateway.
  • the SID of the layer-3 gateway is end. SID of type dt2m.
  • the source IP (source IP, SIP) address of this second ARP request message is EVI SID
  • this EVI SID is the SID that EVI applies for in the two-layer gateway
  • this EVI SID is the SID of end.dt2u type.
  • the first ARP request message is used as the message payload (payload) of the second ARP request message.
  • the layer-3 gateway sends an ARP response packet to the layer-2 gateway.
  • step 405 after the third-layer gateway receives the second ARP request message from the second-layer gateway, it learns ARP information according to the message payload (the first ARP request message) of the second ARP request message, and the ARP information is used for Instructs the layer-3 gateway to send ARP response packets to the hosts in the layer-2 gateway.
  • the APR information may include the MAC address of the host and the IP address of the host.
  • the layer-3 gateway uses the SIP of the second ARP request message as the DIP of the ARP response message.
  • the SIP of the ARP response message is the SID applied by the EVI in the layer-3 gateway, and the SID applied for by the EVI in the layer-3 gateway is end SID of type .dt2u.
  • the layer-3 gateway sends the ARP response message to the layer-2 gateway through the SRv6 tunnel between the layer-3 gateway and the layer-2 gateway according to the outgoing interface determined in step 404 .
  • the layer-2 gateway terminates the SRv6 tunnel with the layer-3 gateway and forwards the ARP response message to the host of the EVI (for example, host 1_11).
  • the third-layer gateway sends a second ARP response message to the second-layer gateway, the second ARP response message includes an SRv6 packet header and the first ARP response message, and the first ARP response message is used as the second ARP response message The payload of the text.
  • the Layer 2 gateway strips the SRv6 message header, and forwards the first ARP response message to the EVI host.
  • the Layer 3 gateway learns the ARP information about the EVI host
  • the EVI host in the Layer 2 gateway learns the ARP information of the Layer 3 gateway
  • the Layer 3 forwarding is reachable between the EVI host in the Layer 2 gateway and the Layer 3 gateway.
  • the two-layer gateway sends the EVI-MAC route to the three-layer gateway, and the EVI-MAC route includes the EVI SID applied for by the EVI in the two-layer gateway.
  • the layer-3 gateway determines the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway. Since the layer-2 gateway no longer sends the MAC address of the EVI host in the layer-2 gateway to the layer-3 gateway, the MAC routing pressure of the layer-3 gateway is effectively reduced. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • FIG. 5 is a schematic diagram of an embodiment of an SRv6-based communication method 50 proposed in an embodiment of the present application.
  • An SRv6-based communication method 50 proposed in the embodiment of the present application includes:
  • the layer-2 gateway disables the function of publishing the host MAC route in the EVI.
  • Step 500 is consistent with the foregoing step 400, and details are not repeated here.
  • the layer-2 gateway generates an EVI-MAC route.
  • the layer-2 gateway advertises the EVI-MAC route to the layer-3 gateway.
  • Steps 501-502 are similar to the aforementioned steps 401-402, and will not be repeated here.
  • steps 501-502 are optional steps, that is, steps 501-502 may not be executed, and when steps 501-502 are not executed (that is, the second-layer gateway does not send the MAC route to the third-layer gateway), step 500 is followed by step 500. 503.
  • the layer-2 gateway sends an ARP request message to the layer-3 gateway.
  • Step 503 is similar to step 404.
  • the second-layer gateway receives the ARP request message of the host of the EVI in the second-layer gateway.
  • the ARP request message sent by the host to the second-layer gateway is called the first ARP request message.
  • the Layer 2 gateway (edge1 node) receives the first ARP request message from the host 1_11.
  • the Layer 2 gateway encapsulates the SRv6 packet header based on the first ARP request packet from the host 1_11, and obtains the ARP request packet carrying the SRv6 packet header.
  • the ARP request packet carrying the SRv6 packet header is called It is the second ARP request packet.
  • the DIP of the second ARP request message is the SID of the layer-3 gateway.
  • the SID of the layer-3 gateway is issued by the layer-3 gateway when the layer-2 gateway establishes an EVPN neighbor relationship with the layer-3 gateway.
  • the SID of the layer-3 gateway is end. SID of type dt2m.
  • the SIP of this second ARP request message is EVI SID, and this EVI SID is the SID that EVI applies for in the two-layer gateway, and this EVI SID is the SID of end.dt2u type.
  • the first ARP request message is used as the message payload (payload) of the second ARP request message.
  • the layer-3 gateway determines the outgoing interface according to the EVI SID in the ARP request message.
  • the three-layer gateway searches the forwarding information table (forwarding information table) on the forwarding plane according to the EVI SID in the ARP request message, and determines the outgoing interface.
  • the source of the forwarding information table is that the control plane of the layer-3 gateway learns the routing table and publishes it to the forwarding plane.
  • the forwarding information table is also called a forwarding table, or a forwarding information base (FIB).
  • the outbound interface is used by the Layer 3 gateway to send packets whose destination address is EVI SID to the Layer 2 gateway.
  • the specific content of the forwarding information table is similar to the routing table shown in Table 4.
  • the forwarding information table can be understood as one or more sets of key-value pairs (key-value), and the three-layer gateway uses the EVI SID as a key to find the corresponding value in the forwarding information table, and the value is the outgoing interface .
  • the layer-3 gateway looks up the forwarding information table according to the EVI SID as the DIP, and determines that the outgoing interface is "0001". Exemplarily, the layer-3 gateway determines the path of the ARP response message according to the outgoing interface.
  • the layer-3 gateway sends an ARP response message to the layer-2 gateway.
  • Step 505 is similar to aforementioned step 405, after the three-layer gateway receives the second ARP request message from the two-layer gateway, learns the ARP information according to the message payload (the first ARP request message) of the second ARP request message, the The ARP information is used to instruct the layer-3 gateway to send an ARP response packet to the host in the layer-2 gateway.
  • the APR information may include the MAC address of the host and the IP address of the host.
  • the layer-3 gateway uses the SIP of the second ARP request message as the DIP of the ARP response message.
  • the SIP of the ARP response message is the SID applied by the EVI in the layer-3 gateway, and the SID applied for by the EVI in the layer-3 gateway is end SID of type .dt2u.
  • the layer-3 gateway sends the ARP response message to the layer-2 gateway through the SRv6 tunnel between the layer-3 gateway and the layer-2 gateway according to the outgoing interface determined in step 504.
  • the layer-2 gateway terminates the SRv6 tunnel with the layer-3 gateway and forwards the ARP response message to the host of the EVI (for example, host 1_11).
  • the third-layer gateway sends a second ARP response message to the second-layer gateway, the second ARP response message includes an SRv6 packet header and the first ARP response message, and the first ARP response message is used as the second ARP response message The payload of the text.
  • the Layer 2 gateway strips the SRv6 message header, and forwards the first ARP response message to the EVI host.
  • the Layer 3 gateway learns the ARP information about the EVI host
  • the EVI host in the Layer 2 gateway learns the ARP information of the Layer 3 gateway
  • the Layer 3 forwarding is reachable between the EVI host in the Layer 2 gateway and the Layer 3 gateway.
  • the EVI SID is carried in the ARP request message sent by the second-layer gateway to the third-layer gateway, and the EVI SID is the SID of the EVI.
  • the layer-3 gateway determines the outgoing interface according to the EVI SID, and the outgoing interface is used by the layer-3 gateway to send a message whose destination address is the EVI SID to the layer-2 gateway. Since the layer-2 gateway no longer sends the MAC address of the EVI host in the layer-2 gateway to the layer-3 gateway, the MAC routing pressure of the layer-3 gateway is effectively reduced. This enables the Layer 3 gateway to support the establishment of communication connections with more hosts, effectively expanding the network capacity.
  • the network device includes hardware structures and/or software modules corresponding to each function.
  • the present application can be implemented in the form of hardware or a combination of hardware and computer software. Whether a certain function is executed by hardware or computer software drives hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art may use different methods to implement the described functions for each specific application, but such implementation should not be regarded as exceeding the scope of the present application.
  • the embodiment of the present application may divide the network device into functional modules according to the above method example, for example, each functional module may be divided corresponding to each function, or two or more functions may be integrated into one processing module.
  • the above-mentioned integrated modules can be implemented in the form of hardware or in the form of software function modules. It should be noted that the division of modules in the embodiment of the present application is schematic, and is only a logical function division, and there may be other division methods in actual implementation.
  • the following introduces the network device in the embodiment of the present application, and the network device introduced in the following has any function of the layer-2 gateway or the layer-3 gateway in the method embodiment above.
  • FIG. 8 is a schematic structural diagram of a network device 800 provided in an embodiment of the present application.
  • the network device 800 includes: a transceiver module 801 for performing steps 402, 404 or 405; a processing module 802 for performing Step 400, 401 or 403.
  • the transceiver module 801 is configured to execute step 502 , 503 or 505 ; the processing module 802 is configured to execute step 500 , 501 or 504 .
  • the transceiver module 801 and the processing module 802 are configured to execute steps 301-305.
  • the network device 800 may correspond to the layer-2 gateway and the layer-3 gateway in the above method embodiments, and each unit in the network device 800 and the above-mentioned other operations and/or functions are to realize the layer-2 gateway and the layer-3 gateway in the method embodiments respectively Or the various steps and methods implemented by the controller, for specific details, refer to the foregoing method embodiments, and for the sake of brevity, details are not repeated here.
  • the network device 800 When the network device 800 processes packets, it only uses the division of the above-mentioned functional modules for illustration. function modules to complete all or part of the functions described above.
  • the network device 800 provided in the above embodiment is of the same concept as the method in the above embodiment corresponding to FIG. 3a, FIG. 4 or FIG.
  • FIG. 9 is a schematic structural diagram of a network device 900 provided in an embodiment of the present application.
  • the network device 900 shown in FIG. 9 shows some specific features, those skilled in the art will realize from the embodiments of the present application that for the sake of brevity, various other features are not shown in FIG. 9 so as not to confuse the present invention. Further relevant aspects of the embodiments disclosed in the application examples.
  • the network device 900 includes one or more processing units (e.g., CPUs) 901, a network interface 902, a programming interface 903, a memory 904, and one or more communication buses 905 for Interconnect the various components.
  • the network device 900 may also omit or add some functional components or units based on the above examples.
  • the network interface 902 is used to connect with one or more other network devices/servers in the network system.
  • communication bus 905 includes circuitry that interconnects and controls communication between system components.
  • Memory 904 can include nonvolatile memory, for example, read-only memory (read-only memory, ROM), programmable read-only memory (programmable ROM, PROM), erasable programmable read-only memory (erasable PROM, EPROM) , Electrically Erasable Programmable Read-Only Memory (electrically EPROM, EEPROM) or flash memory.
  • Memory 904 may also include volatile memory, which may be random access memory (RAM), which acts as an external cache.
  • the memory 904 or the non-transitory computer-readable storage medium of the memory 904 stores the following programs, modules and data structures, or a subset thereof, for example including a transceiver unit (not shown in the figure), an acquisition unit 9041 and a processing Unit 9042.
  • the network device 900 may have any function of the layer-2 gateway or layer-3 gateway in the method embodiment corresponding to FIG. 3a, FIG. 4 or FIG. 5 above.
  • the network device 900 corresponds to a layer-2 gateway, a layer-3 gateway or a controller in the above method embodiments, and each module in the network device 900 and the above-mentioned other operations and/or functions are respectively intended to implement the two methods in the above method embodiments.
  • the layer gateway, layer 3 gateway or controller for details, refer to the method embodiment corresponding to the above-mentioned FIG. 3a, FIG. 4 or FIG.
  • the network interface 902 on the network device 900 can complete the data sending and receiving operation, or the processor can call the program code in the memory, and cooperate with the network interface 902 to realize the function of the sending and receiving unit when necessary .
  • the network device 900 is configured to execute the SRv6-based communication method provided by the embodiment of the present application, for example, execute the SRv6-based communication method corresponding to the embodiment shown in FIG. 3 a , FIG. 4 or FIG. 5 .
  • the specific structure of the network device described in FIG. 9 of this application may be as shown in FIG. 10 .
  • FIG. 10 is a schematic structural diagram of a network device 1000 provided by an embodiment of the present application.
  • the network device 1000 includes: a main control board 1010 and an interface board 1030 .
  • the main control board 1010 is also called a main processing unit (main processing unit, MPU) or a route processor (route processor). , equipment maintenance, protocol processing functions.
  • the main control board 1010 includes: a CPU 1011 and a memory 1012 .
  • the interface board 1030 is also called a line processing unit (line processing unit, LPU), a line card (line card), or a service board.
  • the interface board 1030 is used to provide various service interfaces and implement forwarding of data packets.
  • Service interfaces include but are not limited to Ethernet interfaces, POS (Packet over SONET/SDH) interfaces, etc.
  • the interface board 1030 includes: a central processing unit 1031 , a network processor 1032 , a forwarding entry storage 1034 and a physical interface card (physical interface card, PIC) 1033 .
  • the CPU 1031 on the interface board 1030 is used to control and manage the interface board 1030 and communicate with the CPU 1011 on the main control board 1010 .
  • the network processor 1032 is configured to implement message forwarding processing.
  • the form of the network processor 1032 may be a forwarding chip.
  • the physical interface card 1033 is used to realize the interconnection function of the physical layer, through which the original traffic enters the interface board 1030 , and the processed packets are sent out from the physical interface card 1033 .
  • the physical interface card 1033 includes at least one physical interface, which is also called a physical interface, and the physical interface may be a Flexible Ethernet (FlexE) physical interface.
  • the physical interface card 1033 is also called a daughter card, which can be installed on the interface board 1030, and is responsible for converting the photoelectric signal into a message, checking the validity of the message and forwarding it to the network processor 1032 for processing.
  • the central processing unit 1031 of the interface board 1030 can also execute the functions of the network processor 1032 , such as implementing software forwarding based on a general-purpose CPU, so that the network processor 1032 is not required in the interface board 1030 .
  • the network device 1000 includes multiple interface boards.
  • the network device 1000 further includes an interface board 1040, and the interface board 1040 includes: a central processing unit 1041, a network processor 1042, a forwarding entry storage 1044, and a physical interface card 1043.
  • the network device 1000 further includes a switching fabric unit 1020 .
  • the SFU 1020 may also be called a SFU (switch fabric unit, SFU).
  • SFU switch fabric unit
  • the switching fabric board 1020 is used to complete the data exchange between the interface boards.
  • the interface board 1030 and the interface board 1040 may communicate through the switching fabric board 1020 .
  • the main control board 1010 is coupled to the interface board.
  • the main control board 1010, the interface board 1030, the interface board 1040, and the switching fabric board 1020 are connected through a system bus and/or a system backplane to implement intercommunication.
  • an inter-process communication protocol IPC
  • IPC inter-process communication
  • the network device 1000 includes a control plane and a forwarding plane.
  • the control plane includes a main control board 1010 and a central processing unit 1031.
  • the forwarding plane includes various components for performing forwarding, such as a forwarding entry storage 1034, a physical interface card 1033, and a network processing device 1032.
  • the control plane performs functions such as publishing routes, generating forwarding tables, processing signaling and protocol messages, configuring and maintaining device status, etc., and the control plane sends the generated forwarding tables to the forwarding plane.
  • the network processor 1032 The forwarding table issued above looks up and forwards the packets received by the physical interface card 1033.
  • the forwarding table delivered by the control plane may be stored in the forwarding table item storage 1034 . In some embodiments, the control plane and the forwarding plane may be completely separated and not on the same device.
  • the transceiver unit in the network device 900 may be equivalent to the physical interface card 1033 or the physical interface card 1043 in the network device 1000; the acquisition unit 9041 and the processing unit 9042 in the network device 900 may be equivalent to the central processing unit
  • the processor 1011 or the central processing unit 1031 may also correspond to the program codes or instructions stored in the memory 1012.
  • the operations on the interface board 1040 in the embodiment of the present application are consistent with the operations on the interface board 1030 , and are not repeated for brevity.
  • the network device 1000 in this embodiment may correspond to the Layer 2 gateway or the Layer 3 gateway in the foregoing method embodiments, and the main control board 1010, the interface board 1030 and/or the interface board 1040 in the network device 1000 may implement
  • the functions of the layer-2 gateway or the layer-3 gateway in the above method embodiments and/or various steps implemented will not be repeated here.
  • main control boards there may be one or more main control boards, and when there are multiple main control boards, it may include the main main control board and the standby main control board. There may be one or more interface boards. The stronger the data processing capability of the network device, the more interface boards it provides. There may also be one or more physical interface cards on the interface board. There may be no SFU, or there may be one or more SFUs. When there are multiple SFUs, they can jointly implement load sharing and redundant backup. Under the centralized forwarding architecture, the network device does not need a switching network board, and the interface board undertakes the processing function of the service data of the entire system.
  • the network device can have at least one SFU, through which the data exchange between multiple interface boards can be realized, and large-capacity data exchange and processing capabilities can be provided.
  • the form of the network device can also be that there is only one board, that is, there is no switching fabric board, and the functions of the interface board and the main control board are integrated on this board.
  • the central processing unit and the main control board on the interface board can be combined into one central processing unit on the one board to perform the superimposed functions of the two. Which architecture to use depends on the specific networking deployment scenario, and there is no unique limitation here.
  • the foregoing first network device may be implemented as a virtualization device.
  • the virtualization device may be a virtual machine (virtual machine, VM) running a program for sending packets, a virtual router or a virtual switch.
  • Virtualization devices are deployed on hardware devices (eg, physical servers).
  • the first network device may be implemented based on a common physical server combined with a network functions virtualization (network functions virtualization, NFV) technology.
  • network functions virtualization network functions virtualization
  • the embodiment of the present application also provides a computer-readable storage medium, including instructions, which, when run on a computer, enable the computer to control the network device to execute any one of the implementation manners shown in the foregoing method embodiments.
  • the embodiment of the present application also provides a computer program product, the computer program product includes computer program code, and when the computer program code is run on the computer, the computer is made to execute any one of the implementation manners shown in the foregoing method embodiments.
  • the embodiment of the present application also provides a computer program product, which, when the computer program product runs on the network device, causes the network device to execute the Layer 2 gateway in the method embodiment corresponding to FIG. 3a, FIG. 4 or FIG. 5 above. , Layer 3 gateway or method executed by the controller.
  • the embodiment of the present application also provides a chip system, including a processor and an interface circuit, and the interface circuit is configured to receive instructions and transmit them to the processor.
  • the processor is configured to implement the method in any one of the foregoing method embodiments.
  • the chip system further includes a memory, and there may be one or more processors in the chip system.
  • the processor can be realized by hardware or by software.
  • the processor may be a logic circuit, an integrated circuit, or the like.
  • the processor may be a general-purpose processor, and implements the method in any of the above method embodiments by reading the software code stored in the memory.
  • the memory can be integrated with the processor, or can be set separately from the processor, which is not limited in this application.
  • the memory can be a non-transitory processor, such as a read-only memory ROM, which can be integrated with the processor on the same chip, or can be respectively arranged on different chips.
  • the setting method of the processor is not specifically limited.
  • FIG. 11 is a schematic diagram of a network system 1100 proposed by an embodiment of the present application.
  • the network system 1100 includes: a Layer 2 gateway 1101 and a Layer 3 gateway 1102 .
  • the Layer 2 gateway 1101 and the Layer 3 gateway 1102 may be, for example, physical devices such as routers, switches, or gateways, or virtual devices that support route advertisement and packet forwarding.
  • specific types of the layer-2 gateway 1101 and the layer-3 gateway 1102 are not limited.
  • the network system 1100 further includes a controller 1103, and the controller 1103 may be a server that manages the above-mentioned Layer 2 gateway 1101 and Layer 3 gateway 1102.
  • the Layer 2 gateway 1101 may be the network device 800 , the network device 900 or the network device 1000 .
  • the layer-3 gateway 1102 may be the network device 800 , the network device 900 or the network device 1000 .
  • the controller 1103 may be the network device 800 , the network device 900 or the network device 1000 .
  • FIG. 12 is a schematic diagram of a network system 1200 proposed by an embodiment of the present application.
  • the network system 1200 includes: a first network device 1201 , a second network device 1202 and a third network device 1203 .
  • the first network device 1201 , the second network device 1202 and the third network device 1203 may be, for example, physical devices such as routers, switches, or gateways, or virtual devices that support route advertisement and packet forwarding.
  • specific types of the first network device 1201 , the second network device 1202 and the third network device 1203 are not limited.
  • the network system 1200 shown in FIG. 12 further includes a controller 1204 .
  • the controller 1204 is not shown in the scenario shown in Figure 1b.
  • the second network device 1202 and/or the third network device 1203 generates a media access control EVI-MAC route based on an Ethernet virtual private network instance EVI, where the EVI-MAC route includes an Ethernet virtual private network instance EVI
  • the private network instance segment identifies the EVI SID, the EVI SID is the SRv6 SID that the EVI applies for in the second network device 1202 and/or the third network device 1203, and the MAC address carried in the EVI-MAC route does not include The MAC address of each host in the EVI;
  • the second network device 1202 and/or the third network device 1203 publishes the EVI-MAC route to the first network device 1201;
  • the first network device 1201 receives the EVI-MAC route based on the Ethernet virtual private network instance notified by the second network device 1202 and/or the third network device 1203, and the EVI-MAC route includes the Ethernet virtual private network instance segment Identify the EVI SID, the EVI SID is the SRv6 SID applied by the EVI in the second network device 1202 and/or the third network device 1203, and the MAC address carried in the EVI-MAC route does not include the EVI MAC address of each host;
  • the first network device 1201 obtains the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the first network device 1201 to communicate with the second network device 1202 and/or the third
  • the network device 1203 sends a message whose destination address is the EVI SID.
  • the second network device 1202 and/or the third network device 1203 sends an Address Resolution Protocol ARP request message to the first network device 1201, and the source Internet Protocol SIP address of the ARP request message is Identify the EVI SID for the Ethernet virtual private network instance segment, and the EVI SID is the Ethernet virtual private network example EVI in the second network device 1202 and/or the third network device 1203 in the second network device 1202 and/or the third network device 1203 SRv6 SID applied for by network device 1203;
  • the second network device 1202 and/or the third network device 1203 receives the ARP response message sent from the first network device 1201, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID;
  • the first network device 1201 receives the address resolution protocol ARP request message from the second network device 1202 and/or the third network device 1203, and the source Internet protocol SIP address of the ARP request message is the Ethernet virtual private network instance segment identifier EVI SID, the EVI SID is the SRv6 SID applied for by the Ethernet virtual private network instance EVI at the second network device 1202 and/or the third network device 1203;
  • the first network device 1201 obtains the corresponding relationship between the EVI SID and the outgoing interface according to the EVI SID, and the outgoing interface is used by the first network device 1201 to communicate with the second network device 1202 and/or the third network
  • the device 1203 sends a message whose destination address is the EVI SID;
  • the first network device 1201 sends an ARP response message to the second network device 1202 and/or the third network device 1203 through the outgoing interface, and the destination Internet Protocol DIP address of the ARP response message is the EVI SID.
  • the above-mentioned network devices in various product forms respectively have any functions of the layer-2 gateway or the layer-3 gateway in the above method embodiments, and details are not repeated here.
  • B corresponding to A means that B is associated with A, and B can be determined according to A.
  • determining B according to A does not mean determining B only according to A, and B may also be determined according to A and/or other information.
  • the disclosed system, device and method can be implemented in other ways.
  • the device embodiments described above are only illustrative.
  • the division of units is only a logical function division. In actual implementation, there may be other division methods.
  • multiple units or components can be combined or integrated. to another system, or some features may be ignored, or not implemented.
  • the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be in electrical, mechanical or other forms.
  • a unit described as a separate component may or may not be physically separated, and a component displayed as a unit may or may not be a physical unit, that is, it may be located in one place, or may be distributed to multiple network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.
  • each functional unit in each embodiment of the present application may be integrated into one processing unit, each unit may exist separately physically, or two or more units may be integrated into one unit.
  • the above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

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Abstract

本申请实施例公开了一种基于第6版互联网协议的段路由SRv6的通信方法以及相关装置，该方法可应用于园区网络，该方法包括：二层网关生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，EVI-MAC路由包括以太虚拟私有网实例段标识EVISID,EVI SID是EVI在二层网关申请的SRv6 SID，EVI-MAC路由中携带的MAC地址不包括EVI中各主机的MAC地址；二层网关向三层网关发布EVI-MAC路由。二层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。

Description

一种基于第6版互联网协议的段路由SRv6的通信方法
本申请要求于2021年07月31日提交中国国家知识产权局、申请号为202110876817.5、发明名称为“一种基于SRV6的集中式网关的通信方法，设备和系统”的中国专利申请的优先权，以及于2021年09月16日提交中国国家知识产权局、申请号为202111088863.5、发明名称为“一种基于第6版互联网协议的段路由SRv6的通信方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本申请涉及通信技术领域，尤其涉及一种基于第6版互联网协议的段路由SRv6的通信方法。
背景技术
现有的园区网络中，采用三层网络虚拟化(network virtualization layer 3，NVO3)的虚拟扩展局域网(virtual extensible LAN，VXLAN)技术为园区提供二层网络。
VXLAN是大二层网络中广泛使用的网络虚拟化技术。在源网络设备与目的网络设备之间建立一条逻辑VXLAN隧道，采用媒体接入控制(media access control，MAC)地址封装于用户数据报协议(user datagram protocol，UDP)的封装方式，即，将虚拟机发出的原始以太报文完整的封装在UDP报文中，然后在外层使用物理网络的互联网协议(internet protocol，IP)报文头和以太报文头封装，这样，封装后的报文就像普通IP报文一样，可以通过路由网络转发，使虚拟机彻底摆脱了二、三层网络的结构限制。
目前，园区网络等局域网网络中通常应用VXLAN技术。申请人对VXLAN技术研究发现，应用VXLAN技术的园区网络较难实现新业务的拓展。并且，由于应用VXLAN技术的网络中报文转发是基于IP路由，造成应用VXLAN技术的园区网络无法针对用户的流量进行调优。
发明内容
首先，为了解决园区网络中用户流量调优的问题，本申请提供了一种通信方法，该方法中，网络侧部署基于第6版互联网协议的段路由SRv6，即在园区网络中通过部署SRv6(特别地，部署SRv6-BE)来替代VXLAN，用于转发流量。由此，可以充分理由SRv6可编程的能力，实现对用户的流量进行调优。
进一步地，在应用上述方法的基础上，虽然可以借助SRv6技术实现流量调优，但是，在典型的三层集中式网关场景中，还将面临以下问题，二层网关会向三层网关发送大量无用的以太虚拟专用网EVPN主机MAC路由，导致三层网关MAC路由压力较大。为了解决该问题，本申请还提供了如下几个方面的方法。
第一方面，本申请实施例提出一种基于第6版互联网协议的段路由SRv6的通信方法，该方法由二层网关执行，包括：生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所 述EVI中各主机的MAC地址；向三层网关发布所述EVI-MAC路由。
具体的，以二层网关与三层网关之间分别部署以太虚拟私有网实例(ethernet virtual private network instance，EVI)的场景为例进行说明。首先二层网关与三层网关之间通过边界网关协议(border gateway protocol，BGP)建立以太虚拟私有网(ethernet virtual private network，EVPN)邻居，具体的建立过程，请参阅请求评论(request for comments，RFC)7432协议的约定，此处不作赘述。
二层网关中部署(或者申请)一个或多个EVI，其中，每个EVI包括一个或多个主机，每个EVI通过连接一组或多组用户网络，构成一个或者多个跨地域的二层网络。与二层网关类似，三层网关中部署(或者申请)一个或多个EVI。
本申请实施例中为了便于描述，将该EVI在二层网关申请的段标识(segment identifier，SID)称为EVI SID，换言之，将该二层网关为该EVI配置的SID称之为EVI SID。
需要说明的是，对于同一个EVI，在不同的网关设备中申请的SID是不同的，例如：以EVI1为例进行说明，EVI1在二层网关中申请的SID为EVI SID-1，EVI1在三层网关中申请的SID为EVI SID-2。
由于该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。因此，二层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。
结合第一方面，在第一方面的一种可能实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
具体的，该EVI-MAC路由中携带的MAC地址可以是该二层网关的MAC地址。或者，该EVI-MAC路由中携带的MAC地址还可以是全F的MAC地址，该全F的MAC地址又称为字段值为全F的MAC地址。示例性的，该MAC路由中路由前缀的MAC地址的字段值为“0xffffffffffff”。可以理解的是，EVI-MAC路由中携带的MAC地址还可以是其它的字段值，此处不作限制。
结合第一方面，在第一方面的一种可能实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
具体的，默认状态下，二层网关向三层网关发布EVI中主机MAC路由。当二层网关使能关闭向三层网关发布EVI中主机MAC路由后，二层网关生成的MAC路由中不包括主机的MAC地址，该MAC路由的目的地是三层网关。通过关闭二层网关发布EVI中主机MAC路由的功能，使得三层网关不会收到二层网关中各主机的MAC地址，进而避免三层网关保存该主机的MAC地址，降低三层网关的MAC路由压力。可以理解的是，二层网关也可以通过配置的方式实现不再向三层网关发送主机的MAC地址，此处不作限制。
在另一种可能的实现方式中，二层网关可以向三层网关发布EVI中主机MAC路由，该MAC路由包括EVI中各主机的MAC地址。此时，三层网关收到该MAC路由后，不保存该EVI 中各主机的MAC地址。
结合第一方面，在第一方面的一种可能实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
具体的，该EVI-MAC路由中还包括指示信息，该指示信息指示三层网关收到该EVI-MAC路由后，避免将EVI-MAC路由下发到转发面的MAC转发表(forwarding table)。MAC转发表记录MAC地址与出接口的映射关系。
结合第一方面，在第一方面的一种可能实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
具体的，该EVI-MAC路由中还可以包括拓展团体属性(extended community)，该拓展团体属性用于承载前述的指示信息。则三层网关收到该EVI-MAC路由后，根据该EVI-MAC路由的拓展团体属性(该拓展团体属性中承载该指示信息)，避免将EVI-MAC路由下发到转发面的MAC转发表。
可选的，该指示信息可以是该拓展团体属性，即该拓展团体属性用于指示三层网关避免将EVI-MAC路由下发到转发面的MAC转发表。
结合第一方面，在第一方面的一种可能实现方式中，所述二层网关向所述三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；所述二层网关接收所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
具体的，地址解析协议(address resolution protocol，ARP)协议是用来将互联网协议(Internet protocol，IP)地址解析为MAC地址的协议。在局域网中，当网络设备(或者主机)有数据要发送给另一个网络设备(或主机)时，它必须知道对方的网络层地址(即IP地址)。但是仅有IP地址是不够的，因为IP数据报文必须封装成帧才能通过物理网络发送，因此发送方还必须有接收方的物理地址(MAC地址)，所以需要一个从IP地址到物理地址的映射。ARP就是实现这个功能的协议。通过ARP请求过程和ARP应答过程完成地址解析。
由于二层网关向三层网关发送的ARP请求报文的源IP(source IP，SIP)地址为EVI SID，三层网关向二层网关发送的ARP响应报文的目的IP(destination IP，DIP)地址为EVI SID，因此保证二层网关与三层网关之间的ARP报文可以顺利抵达目的地，ARP请求过程和ARP应答过程可以顺利执行。通过上述流程，三层网关学习关于EVI的主机的ARP信息，二层网关中EVI的主机学习三层网关的ARP信息，二层网关中EVI的主机与三层网关之间实现三层转发可达。
结合第一方面，在第一方面的一种可能实现方式中，所述EVI SID为end.dt2u类型的SID。具体的，end.dt2u类型的SID具有解封装和单播MAC的端点“Endpoint with  decapsulation and unicast MAC”。示例性的，end.dt2u类型的SID用于EVPN桥接单播用例“EVPN Bridging Unicast use case”。
结合第一方面，在第一方面的一种可能实现方式中，所述二层网关和所述三层网关部署于园区网络。园区(campus)网络，通常是指大学的校园网或企业的内部网。主要特征：园区网络中的网络设备(交换机，路由器等)以及传输媒介(光纤等)等通常园区网络所有者拥有，园区网络所有者例如是企业用户，大学或政府机构等。通过上述方法使得园区网络等具有二层网关和三层网关的局域网网络可以成功应用SRv6技术。使得园区网络可以针对用户的流量进行调优，提升网络带宽的利用率。同时SRv6技术具有可编程的优点，因此可以有效降低园区网络的实现新业务难度。
结合第一方面，在第一方面的一种可能实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
在另一种可能的实现方式中，所述二层网关基于IPv6段路由策略SRv6policy进行报文转发。
第二方面，本申请实施例提出一种基于第6版互联网协议的段路由SRv6的通信方法，所述方法由三层网关执行，包括：
接收二层网关通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文。
具体的，以二层网关与三层网关之间分别部署以太虚拟私有网实例(ethernet virtual private network instance，EVI)的场景为例进行说明。首先二层网关与三层网关之间通过边界网关协议(border gateway protocol，BGP)建立以太虚拟私有网(ethernet virtual private network，EVPN)邻居，具体的建立过程，请参阅请求评论(request for comments，RFC)7432协议的约定，此处不作赘述。
二层网关中部署(或者申请)一个或多个EVI，其中，每个EVI包括一个或多个主机，每个EVI通过连接一组或多组用户网络，构成一个或者多个跨地域的二层网络。与二层网关类似，三层网关中部署(或者申请)一个或多个EVI。
当三层网关接收EVI-MAC路由后，确定需要根据该EVI-MAC路由携带的EVI SID查找出接口。出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。
需要说明的是，对于同一个EVI，在不同的网关设备中申请的SID是不同的，例如：以EVI1为例进行说明，EVI1在二层网关中申请的SID为EVI SID-1，EVI1在三层网关中申请的SID为EVI SID-2。
由于该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。因此，二 层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。当三层网关接收EVI-MAC路由后，确定需要根据该EVI-MAC路由携带的EVI SID查找出接口。出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。在三层网关未使用二层网关中主机的MAC地址的前提下，依然保证二层网关与三层网关之间报文的成功交互。
结合第二方面，在第二方面的一种可能实现方式中，所述根据所述EVI SID,获得所述EVI SID和出接口的对应关系，包括：根据所述EVI SID查找路由表，获得所述对应关系，其中，所述路由表包括所述对应关系。
三层网关根据该EVI-MAC路由中的EVI SID作为目的IP(destination IP，DIP)地址，在转发面查找路由表(routing table)，确定出接口。该路由表又称为路由信息表(routing information table)或者路由信息库(routing information base，RIB)。
具体的，路由表可以理解为一组或多组键值对(key-value)，三层网关将EVI SID作为key，在路由表中查找对应的value，该value为出接口。示例性的，三层网关根据该出接口确定ARP响应报文的路径。
结合第二方面，在第二方面的一种可能实现方式中，所述EVI-MAC路由包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表，所述方法还包括：根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
具体的，MAC转发表记录MAC地址与出接口的映射关系。
结合第二方面，在第二方面的一种可能实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
具体的，该EVI-MAC路由中还可以包括拓展团体属性(extended community)，该拓展团体属性用于承载前述的指示信息。则三层网关收到该EVI-MAC路由后，根据该EVI-MAC路由的拓展团体属性(该拓展团体属性中承载该指示信息)，避免将EVI-MAC路由下发到转发面的MAC转发表。
可选的，该指示信息可以是该拓展团体属性，即该拓展团体属性用于指示三层网关避免将EVI-MAC路由下发到转发面的MAC转发表。
结合第二方面，在第二方面的一种可能实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
具体的，该EVI-MAC路由中携带的MAC地址可以是该二层网关的MAC地址。或者，该EVI-MAC路由中携带的MAC地址还可以是全F的MAC地址，该全F的MAC地址又称为字段值为全F的MAC地址。示例性的，该MAC路由中路由前缀的MAC地址的字段值为 “0xffffffffffff”。可以理解的是，EVI-MAC路由中携带的MAC地址还可以是其它的字段值，此处不作限制。
结合第二方面，在第二方面的一种可能实现方式中，所述方法还包括：接收来自所述二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；根据所述EVI SID和所述出接口的对应关系,确定通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；通过所述出接口向所述二层网关发送所述ARP响应报文。
具体的，地址解析协议(address resolution protocol，ARP)协议是用来将互联网协议(Internet protocol，IP)地址解析为MAC地址的协议。在局域网中，当网络设备(或者主机)有数据要发送给另一个网络设备(或主机)时，它必须知道对方的网络层地址(即IP地址)。但是仅有IP地址是不够的，因为IP数据报文必须封装成帧才能通过物理网络发送，因此发送方还必须有接收方的物理地址(MAC地址)，所以需要一个从IP地址到物理地址的映射。ARP就是实现这个功能的协议。通过ARP请求过程和ARP应答过程完成地址解析。
由于二层网关向三层网关发送的ARP请求报文的源IP(source IP，SIP)地址为EVI SID，三层网关向二层网关发送的ARP响应报文的目的IP(destination IP，DIP)地址为EVI SID。三层网关根据该EVI SID获取对应的出接口，并通过该出接口向二层网关发送ARP响应报文，因此保证二层网关与三层网关之间的ARP报文可以顺利抵达目的地，ARP请求过程和ARP应答过程可以顺利执行。通过上述流程，三层网关学习关于EVI的主机的ARP信息，二层网关中EVI的主机学习三层网关的ARP信息，二层网关中EVI的主机与三层网关之间实现三层转发可达。
结合第二方面，在第二方面的一种可能实现方式中，所述EVI SID为end.dt2u类型的SID。具体的，end.dt2u类型的SID具有解封装和单播MAC的端点“Endpoint with decapsulation and unicast MAC”。示例性的，end.dt2u类型的SID用于EVPN桥接单播用例“EVPN Bridging Unicast use case”。
结合第二方面，在第二方面的一种可能实现方式中，所述二层网关和所述三层网关部署于园区网络。园区(campus)网络，通常是指大学的校园网或企业的内部网。主要特征：园区网络中的网络设备(交换机，路由器等)以及传输媒介(光纤等)等通常园区网络所有者拥有，园区网络所有者例如是企业用户，大学或政府机构等。通过上述方法使得园区网络等具有二层网关和三层网关的局域网网络可以成功应用SRv6技术。使得园区网络可以针对用户的流量进行调优，提升网络带宽的利用率。同时SRv6技术具有可编程的优点，因此可以有效降低园区网络的实现新业务难度。
结合第二方面，在第二方面的一种可能实现方式中，所述三层网关为基于IPv6段路由 尽力而为SRv6BE进行报文转发的集中式网关。
在另一种可能的实现方式中，所述二层网关基于IPv6段路由策略SRv6policy进行报文转发。
第三方面，本身实施例提出一种基于第6版互联网协议的段路由SRv6的通信方法，所述方法由二层网关执行，所述方法包括：
向三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID为所述二层网关中以太虚拟私有网示例EVI在所述二层网关申请的SRv6 SID；
接收来自所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
具体的，以二层网关与三层网关之间分别部署EVI的场景为例进行说明。首先二层网关与三层网关之间通过BGP建立以太虚拟私有网EVPN邻居，具体的建立过程，请参阅RFC7432协议的约定，此处不作赘述。
二层网关中部署(或者申请)一个或多个EVI，其中，每个EVI包括一个或多个主机，每个EVI通过连接一组或多组用户网络，构成一个或者多个跨地域的二层网络。与二层网关类似，三层网关中部署(或者申请)一个或多个EVI。
需要说明的是，对于同一个EVI，在不同的网关设备中申请的SID是不同的，例如：以EVI1为例进行说明，EVI1在二层网关中申请的SID为EVI SID-1，EVI1在三层网关中申请的SID为EVI SID-2。
二层网关向三层网关发送的ARP请求报文中携带EVI SID，该EVI SID为EVI的SID。三层网关根据该EVI SID确定出接口，该出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。由于二层网关不再向三层网关发送二层网关中EVI的主机的MAC地址，有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。三层网关根据该EVI SID获取对应的出接口，并通过该出接口向二层网关发送ARP响应报文，因此保证二层网关与三层网关之间的ARP报文可以顺利抵达目的地，ARP请求过程和ARP应答过程可以顺利执行。通过上述流程，三层网关学习关于EVI的主机的ARP信息，二层网关中EVI的主机学习三层网关的ARP信息，二层网关中EVI的主机与三层网关之间实现三层转发可达。
结合第三方面，在第三方面的一种可能实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
具体的，默认状态下，二层网关向三层网关发布EVI中主机MAC路由。当二层网关使能关闭向三层网关发布EVI中主机MAC路由后，二层网关生成的MAC路由中不包括主机的MAC地址，该MAC路由的目的地是三层网关。通过关闭二层网关发布EVI中主机MAC路由的功能，使得三层网关不会收到二层网关中各主机的MAC地址，进而避免三层网关保存该主机的MAC地址，降低三层网关的MAC路由压力。可以理解的是，二层网关也可以通过配 置的方式实现不再向三层网关发送主机的MAC地址，此处不作限制。
在另一种可能的实现方式中，二层网关可以向三层网关发布EVI中主机MAC路由，该MAC路由包括EVI中各主机的MAC地址。此时，三层网关收到该MAC路由后，不保存该EVI中各主机的MAC地址。
结合第三方面，在第三方面的一种可能实现方式中，所述EVI SID为end.dt2u类型的SID。具体的，end.dt2u类型的SID具有解封装和单播MAC的端点“Endpoint with decapsulation and unicast MAC”。示例性的，end.dt2u类型的SID用于EVPN桥接单播用例“EVPN Bridging Unicast use case”。
结合第三方面，在第三方面的一种可能实现方式中，所述方法还包括：生成基于所述EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括所述EVI SID,所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；向所述三层网关发布所述EVI-MAC路由。
由于该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。因此，二层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。
结合第三方面，在第三方面的一种可能实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
具体的，该EVI-MAC路由中还包括指示信息，该指示信息指示三层网关收到该EVI-MAC路由后，避免将EVI-MAC路由下发到转发面的MAC转发表(forwarding table)。MAC转发表记录MAC地址与出接口的映射关系。
结合第三方面，在第三方面的一种可能实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
具体的，该EVI-MAC路由中还可以包括拓展团体属性(extended community)，该拓展团体属性用于承载前述的指示信息。则三层网关收到该EVI-MAC路由后，根据该EVI-MAC路由的拓展团体属性(该拓展团体属性中承载该指示信息)，避免将EVI-MAC路由下发到转发面的MAC转发表。
可选的，该指示信息可以是该拓展团体属性，即该拓展团体属性用于指示三层网关避免将EVI-MAC路由下发到转发面的MAC转发表。
结合第三方面，在第三方面的一种可能实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
具体的，该EVI-MAC路由中携带的MAC地址可以是该二层网关的MAC地址。或者，该 EVI-MAC路由中携带的MAC地址还可以是全F的MAC地址，该全F的MAC地址又称为字段值为全F的MAC地址。示例性的，该MAC路由中路由前缀的MAC地址的字段值为“0xffffffffffff”。可以理解的是，EVI-MAC路由中携带的MAC地址还可以是其它的字段值，此处不作限制。
结合第三方面，在第三方面的一种可能实现方式中，所述二层网关和所述三层网关部署于园区网络。园区(campus)网络，通常是指大学的校园网或企业的内部网。主要特征：园区网络中的网络设备(交换机，路由器等)以及传输媒介(光纤等)等通常园区网络所有者拥有，园区网络所有者例如是企业用户，大学或政府机构等。通过上述方法使得园区网络等具有二层网关和三层网关的局域网网络可以成功应用SRv6技术。使得园区网络可以针对用户的流量进行调优，提升网络带宽的利用率。同时SRv6技术具有可编程的优点，因此可以有效降低园区网络的实现新业务难度。
结合第三方面，在第三方面的一种可能实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
在另一种可能的实现方式中，所述二层网关基于IPv6段路由策略SRv6policy进行报文转发。
第四方面，本申请实施例提出一种基于第6版互联网协议的段路由SRv6的通信方法，所述方法由三层网关执行，所述方法包括：接收来自二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID是以太虚拟私有网实例EVI在所述二层网关申请的SRv6 SID；根据所述EVI SID获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文；通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
具体的，以二层网关与三层网关之间分别部署EVI的场景为例进行说明。首先二层网关与三层网关之间通过BGP建立以太虚拟私有网EVPN邻居，具体的建立过程，请参阅RFC7432协议的约定，此处不作赘述。
二层网关中部署(或者申请)一个或多个EVI，其中，每个EVI包括一个或多个主机，每个EVI通过连接一组或多组用户网络，构成一个或者多个跨地域的二层网络。与二层网关类似，三层网关中部署(或者申请)一个或多个EVI。
需要说明的是，对于同一个EVI，在不同的网关设备中申请的SID是不同的，例如：以EVI1为例进行说明，EVI1在二层网关中申请的SID为EVI SID-1，EVI1在三层网关中申请的SID为EVI SID-2。
二层网关向三层网关发送的ARP请求报文中携带EVI SID，该EVI SID为EVI的SID。三层网关根据该EVI SID确定出接口，该出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。由于二层网关不再向三层网关发送二层网关中EVI的主机的MAC地址， 有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。三层网关根据该EVI SID获取对应的出接口，并通过该出接口向二层网关发送ARP响应报文，因此保证二层网关与三层网关之间的ARP报文可以顺利抵达目的地，ARP请求过程和ARP应答过程可以顺利执行。
结合第四方面，在第四方面的一种可能实现方式中，所述三层网关根据所述EVI SID,获得所述EVI SID和出接口的对应关系，包括：根据所述EVI SID查找转发信息表，获得所述对应关系，其中，所述转发表包括所述对应关系。
三层网关根据ARP请求报文中的EVI SID，在转发面查找转发信息表(forwarding information table)，确定出接口。该转发信息表的来源为三层网关的控制面学习路由表后发布至转发面。转发信息表又称为转发表，或者转发信息库(forwarding information base，FIB)。出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。
该转发信息表的具体内容与路由表类似。具体的，将该转发信息表可以理解为一组或多组键值对(key-value)，三层网关将EVI SID作为key，在该转发信息表中查找对应的value，该value为出接口。
结合第四方面，在第四方面的一种可能实现方式中，所述EVI SID为end.dt2u类型的SID。具体的，end.dt2u类型的SID具有解封装和单播MAC的端点“Endpoint with decapsulation and unicast MAC”。示例性的，end.dt2u类型的SID用于EVPN桥接单播用例“EVPN Bridging Unicast use case”。
结合第四方面，在第四方面的一种可能实现方式中，所述方法还包括：接收来自所述二层网关的媒体接入控制MAC路由，所述EVI-MAC路由包括所述EVI SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址。由于该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。因此，二层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。
结合第四方面，在第四方面的一种可能实现方式中，所述EVI-MAC路由包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表，所述方法还包括：根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
具体的，该EVI-MAC路由中还包括指示信息，该指示信息指示三层网关收到该EVI-MAC路由后，避免将EVI-MAC路由下发到转发面的MAC转发表(forwarding table)。MAC转发表记录MAC地址与出接口的映射关系。
结合第四方面，在第四方面的一种可能实现方式中，所述EVI-MAC路由中携带的所述 MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
具体的，该EVI-MAC路由中携带的MAC地址可以是该二层网关的MAC地址。或者，该EVI-MAC路由中携带的MAC地址还可以是全F的MAC地址，该全F的MAC地址又称为字段值为全F的MAC地址。示例性的，该MAC路由中路由前缀的MAC地址的字段值为“0xffffffffffff”。可以理解的是，EVI-MAC路由中携带的MAC地址还可以是其它的字段值，此处不作限制。
结合第四方面，在第四方面的一种可能实现方式中，所述二层网关和所述三层网关部署于园区网络。园区(campus)网络，通常是指大学的校园网或企业的内部网。主要特征：园区网络中的网络设备(交换机，路由器等)以及传输媒介(光纤等)等通常园区网络所有者拥有，园区网络所有者例如是企业用户，大学或政府机构等。通过上述方法使得园区网络等具有二层网关和三层网关的局域网网络可以成功应用SRv6技术。使得园区网络可以针对用户的流量进行调优，提升网络带宽的利用率。同时SRv6技术具有可编程的优点，因此可以有效降低园区网络的实现新业务难度。
结合第四方面，在第四方面的一种可能实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
在另一种可能的实现方式中，所述二层网关基于IPv6段路由策略SRv6policy进行报文转发。
第五方面，本申请实施例提出一种通信系统，该通信系统包括：二层网关和三层网关，该通信系统具体包括：
二层网关生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
二层网关向三层网关发布所述EVI-MAC路由；
三层网关接收二层网关通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
三层网关根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文。
本申请实施例中，由于该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。因此，二层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。
结合第五方面，在第五方面的一种可能实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
结合第五方面，在第五方面的一种可能实现方式中，三层网关根据所述EVI SID,获得所述EVI SID和出接口的对应关系，包括：三层网关根据所述EVI SID查找路由表，获得所述对应关系，其中，所述路由表包括所述对应关系。
结合第五方面，在第五方面的一种可能实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
结合第五方面，在第五方面的一种可能实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。三层网关根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
结合第五方面，在第五方面的一种可能实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
结合第五方面，在第五方面的一种可能实现方式中，所述二层网关向所述三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
三层网关根据所述EVI SID和所述出接口的对应关系,确定通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
所述二层网关接收所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
结合第五方面，在第五方面的一种可能实现方式中，所述EVI SID为end.dt2u类型的SID。
结合第五方面，在第五方面的一种可能实现方式中，所述二层网关和所述三层网关部署于园区网络。
结合第五方面，在第五方面的一种可能实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
在另一种可能的实现方式中，所述二层网关基于IPv6段路由策略SRv6policy进行报文转发。
第六方面，本申请实施例提出一种通信系统，该通信系统包括：二层网关和三层网关，该通信系统具体包括：
二层网关向三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID为所述二层网关中以太虚拟私有网示例EVI在所述二层网关申请的SRv6 SID；
二层网关接收来自所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
三层网关接收来自二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID是以太虚拟私有网实例EVI在所述二层网关申请的SRv6 SID；
三层网关根据所述EVI SID获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文；
三层网关通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
本申请实施例中，由于该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。因此，二层网关向三层网关发布该EVI-MAC路由后，三层网关并不会收到二层网关中主机的MAC地址。有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。当三层网关接收EVI-MAC路由后，确定需要根据该EVI-MAC路由携带的EVI SID查找出接口。出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。在三层网关未使用二层网关中主机的MAC地址的前提下，依然保证二层网关与三层网关之间报文的成功交互。
结合第六方面，在第六方面的一种可能实现方式中，二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
结合第六方面，在第六方面的一种可能实现方式中，根据所述EVI SID查找转发信息表，获得所述对应关系，其中，所述转发表包括所述对应关系。
结合第六方面，在第六方面的一种可能实现方式中，所述EVI SID为end.dt2u类型的SID。
结合第六方面，在第六方面的一种可能实现方式中，二层网关生成基于所述EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括所述EVI SID,所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
二层网关向所述三层网关发布所述EVI-MAC路由；
三层网关接收来自所述二层网关的媒体接入控制MAC路由，所述EVI-MAC路由包括所述EVI SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址。
结合第六方面，在第六方面的一种可能实现方式中，EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
三层网关根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
结合第六方面，在第六方面的一种可能实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
结合第六方面，在第六方面的一种可能实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
结合第六方面，在第六方面的一种可能实现方式中，所述二层网关和所述三层网关部署于园区网络。
结合第六方面，在第六方面的一种可能实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
第七方面，本申请实施例提出一种网络设备，用作二层网关，包括：处理模块和收发模块；
处理模块，用于生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
收发模块，用于向三层网关发布所述EVI-MAC路由。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
在一种可能的实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
在一种可能的实现方式中，所述收发模块，还用于向所述三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
所述收发模块，还用于接收所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
第八方面，本申请实施例提出一种网络设备，所述网络设备包括：收发模块和处理模块；
所述收发模块，用于接收二层网关通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
所述处理模块，用于根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文。
在一种可能的实现方式中，所述处理模块，还用于根据所述EVI SID查找路由表，获得所述对应关系，其中，所述路由表包括所述对应关系。
在一种可能的实现方式中，所述处理模块，还用于根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述收发模块，还用于接收来自所述二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
所述处理模块，还用于根据所述EVI SID和所述出接口的对应关系,确定通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
所述收发模块，还用于通过所述出接口向所述二层网关发送所述ARP响应报文。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述三层网关为基于IPv6段路由尽力而为SRv6BE进行报文转发的集中式网关。
第九方面，本申请实施例提出一种网络设备，所述网络设备包括：收发模块和处理模块；
所述收发模块，用于向三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID为所述二层网关中以太虚拟私有网示例EVI在所述二层网关申请的SRv6 SID；
所述收发模块，还用于接收来自所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
在一种可能的实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述处理模块，用于生成基于所述EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括所述EVI SID,所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
所述收发模块，还用于向所述三层网关发布所述EVI-MAC路由。
在一种可能的实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
第十方面，本申请实施例提出一种网络设备，用作三层网关，所述网络设备包括：收发模块和处理模块；
所述收发模块，用于接收来自二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID是以太 虚拟私有网实例EVI在所述二层网关申请的SRv6 SID；
所述处理模块，用于根据所述EVI SID获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文；
所述收发模块，还用于通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
在一种可能的实现方式中，所述处理模块，还用于根据所述EVI SID查找转发信息表，获得所述对应关系，其中，所述转发表包括所述对应关系。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述收发模块，还用于接收来自所述二层网关的媒体接入控制MAC路由，所述EVI-MAC路由包括所述EVI SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址。
在一种可能的实现方式中，所述处理模块，还用于根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
第十一方面，本申请实施例提出一种网络设备，用作二层网关，包括：处理器和收发器；
处理器，用于生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
收发器，用于向三层网关发布所述EVI-MAC路由。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
在一种可能的实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
在一种可能的实现方式中，所述收发器，还用于向所述三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
所述收发器，还用于接收所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
第十二方面，本申请实施例提出一种网络设备，用作三层网关，所述网络设备包括：收发器和处理器；
所述收发器，用于接收二层网关通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
所述处理器，用于根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文。
在一种可能的实现方式中，所述处理器，还用于根据所述EVI SID查找路由表，获得所述对应关系，其中，所述路由表包括所述对应关系。
在一种可能的实现方式中，所述处理器，还用于根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述收发器，还用于接收来自所述二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
所述处理器，还用于根据所述EVI SID和所述出接口的对应关系,确定通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
所述收发器，还用于通过所述出接口向所述二层网关发送所述ARP响应报文。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述三层网关为基于IPv6段路由尽力而为SRv6BE进行报文转发的集中式网关。
第十三方面，本申请实施例提出一种网络设备，用作二层网关，所述网络设备包括：收发器和处理器；
所述收发器，用于向三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID为所述二层网关中以太虚拟私有网示例EVI在所述二层网关申请的SRv6 SID；
所述收发器，还用于接收来自所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
在一种可能的实现方式中，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述处理器，用于生成基于所述EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括所述EVI SID,所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
所述收发器，还用于向所述三层网关发布所述EVI-MAC路由。
在一种可能的实现方式中，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文转发。
第十四方面，本申请实施例提出一种网络设备，用作三层网关，所述网络设备包括：收发器和处理器；
所述收发器，用于接收来自二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID是以太虚拟私有网实例EVI在所述二层网关申请的SRv6 SID；
所述处理器，用于根据所述EVI SID获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文；
所述收发器，还用于通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
在一种可能的实现方式中，所述处理器，还用于根据所述EVI SID查找转发信息表，获得所述对应关系，其中，所述转发表包括所述对应关系。
在一种可能的实现方式中，所述EVI SID为end.dt2u类型的SID。
在一种可能的实现方式中，所述收发器，还用于接收来自所述二层网关的媒体接入控制MAC路由，所述EVI-MAC路由包括所述EVI SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址。
在一种可能的实现方式中，所述处理器，还用于根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
在一种可能的实现方式中，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
在一种可能的实现方式中，所述二层网关和所述三层网关部署于园区网络。
在一种可能的实现方式中，所述二层网关基于IPv6段路由尽力而为SRv6BE进行报文 转发。
第十五方面，提供了一种通信系统，其特征在于，所述通信系统包括如第七方面或第八方面所述的网络设备。
第十六方面，提供了一种通信系统，其特征在于，所述通信系统包括如第九方面或第十方面所述的网络设备。
第十七方面，提供了一种通信系统，其特征在于，所述通信系统包括如第十一方面或第十二方面所述的网络设备。
第十八方面，提供了一种通信系统，其特征在于，所述通信系统包括如第十三方面或第十四方面所述的网络设备。
本申请第十九方面提供一种计算机存储介质，该计算机存储介质可以是非易失性的；该计算机存储介质中存储有计算机可读指令，当该计算机可读指令被处理器执行时实现第一方面、第二方面、第三方面、或者第四方面中任意一种实现方式中的方法。
本申请第二十方面提供一种包含指令的计算机程序产品，当其在计算机上运行时，使得计算机执行第一方面、第二方面、第三方面、或者第四方面中任意一种实现方式中的方法。
本申请第二十一方面提供一种芯片系统，该芯片系统包括处理器，用于支持网络设备实现上述方面中所涉及的功能，例如，发送或处理上述方法中所涉及的数据和/或信息。在一种可能的设计中，芯片系统还包括存储器，存储器，用于保存网络设备必要的程序指令和数据。该芯片系统，可以由芯片构成，也可以包括芯片和其他分立器件。
附图说明
图1a为集中式网关示意图；
图1b为VXLAN架构下集中式网关示意图；
图2a为ARP请求过程的流程示意图；
图2b为ARP响应过程的流程示意图；
图3a为本申请实施例提出的一种基于SRv6的通信方法30的实施例示意图；
图3b为本申请实施例中ARP报文交互示意图；
图3c为本申请实施例中ARP请求报文或者ARP响应报文结构示意图；
图3d为本申请实施例中一种SRv6BE报文结构示意图；
图4为本申请实施例提出的一种基于SRv6的通信方法40的实施例示意图；
图5为本申请实施例提出的一种基于SRv6的通信方法50的实施例示意图；
图6为本申请实施例提出的一种拓展团体属性的示意图；
图7为本申请实施例提出的一种应用场景示意图；
图8为本申请实施例提供的一种网络设备800的结构示意图；
图9为本申请实施例提供的一种网络设备900的结构示意图；
图10为本申请实施例提供的一种网络设备1000的结构示意图；
图11为本申请实施例提出的一种网络系统1100示意图；
图12为本申请实施例提出的一种网络系统1200示意图。
具体实施方式
下面，对本申请实施例进行描述。显然，所描述的实施例仅仅是本申请一部分的实施例，而不是全部的实施例。本领域普通技术人员可知，随着新应用场景的出现，本申请实施例提供的技术方案对于类似的技术问题，同样适用。
本申请的说明书和权利要求书及上述附图中的术语“第一”、“第二”等是用于区别类似的对象，而不必用于描述特定的顺序或先后次序。应该理解这样使用的描述在适当情况下可以互换，以便使实施例能够以除了在本申请图示或描述的内容以外的顺序实施。此外，术语“包括”和“具有”以及他们的任何变形，意图在于覆盖不排他的包含，例如，包含了一系列步骤或模块的过程、方法、系统、产品或设备不必限于清楚地列出的那些步骤或模块，而是可包括没有清楚地列出的或对于这些过程、方法、产品或设备固有的其它步骤或模块。在本申请中出现的对步骤进行的命名或者编号，并不意味着必须按照命名或者编号所指示的时间/逻辑先后顺序执行方法流程中的步骤，已经命名或者编号的流程步骤可以根据要实现的技术目的变更执行顺序，只要能达到相同或者相类似的技术效果即可。本申请中所出现的单元的划分，是一种逻辑上的划分，实际应用中实现时可以有另外的划分方式，例如多个单元可以结合成或集成在另一个系统中，或一些特征可以忽略，或不执行，另外，所显示的或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，单元之间的间接耦合或通信连接可以是电性或其他类似的形式，本申请中均不作限定。并且，作为分离部件说明的单元或子单元可以是也可以不是物理上的分离，可以是也可以不是物理单元，或者可以分布到多个电路单元中，可以根据实际的需要选择其中的部分或全部单元来实现本申请方案的目的。
首先，介绍本申请实施例涉及的一些技术概念。
分段路由(segment routing，SR)：是基于源路由的理念而设计的在网络中转发数据包的一种协议。SR将网络路径划分为一个个段，并且为这些段和网络节点分配分段标识(segment id，SID)，通过对SID进行有序排列，可以得到段列表(SID List，在SR-MPLS中也称标签栈)，SID List可以指示一条转发路径。在SR技术中，头节点会向数据包添加标签栈，中间节点可以根据标签栈转发至下一个节点，直至数据包到达目的节点。例如在数据包的包头中，插入<SID1，SID2，SID3>，则数据包packet会首先转发给SID1对应的节点，之后转发给SID2对应的节点，之后转发给SID3对应的节点。其中，SR-MPLS的中英文全称为分段路由多协议标签交换(segment routing multi-protocol label switching)。
基于第6版互联网协议(Internet Protocol Version 6，IPv6)的分段路由(SRv6)：是指将SR技术应用在IPv6网络中。使用IPv6地址(128bits)作为SID的表现形式。在转发数据包时，支持SRv6的网络设备会按照数据包中的目的地址(destination address，DA)，查询本地段标识表(local sid table)，当数据包的目的地址与本地段标识表中的任一SID符合最长匹配原则时，则按照本地段标识表中的该SID相关的策略，执行该策略对应的操作，例如，可以将数据包从该SID对应的出接口转发出去；如果数据包的目的地址与本地段标识表中的每个SID均不最长匹配，则再查IPv6的转发表，按照IPv6的转发表进行最长匹配转发。
SR策略(SR policy)是一种SR的流量工程机制。通常，一个SR Policy包括头节点(headend)、颜色标识(color)以及端点(endpoint)，以及指示转发路径的段标识列表。其中，Headend用于标识执行SR Policy的头节点，Color用于SR与业务属性相关联，例如与低时延、高带宽等业务属性相关联，以概括该SR Policy的服务能力，Endpoint用于标识SR Policy的目的地址。通常，通过(headend，color，endpoint)确定一条SR Policy。对同一个headend来说，也可以通过(color，endpoint)来确定一条SR Policy。SR policy可以包括一个或多个段标识列表，以实现负载均衡，多路径备份等功能。头节点在转发报文时，可以根据该SR policy确定报文对应的段标识列表，从而确定转发该报文的转发路径，并将该段标识列表封装到报文中以指示该报文的候选路径，该候选路径包括显示候选路径和动态候选路径。
SRv6尽力而为(SRv6best effort，SRv6BE)：
在SRv6技术中，可以仅使用一个业务SID指示报文在IP网络中进行尽力而为的转发，该项技术称为SRv6BE。在SRv6BE的报文中不封装段路由报头(segment routing header，SRH)。
虚拟扩展局域网(virtual extensible LAN，VXLAN)：
VXLAN是大二层网络中广泛使用的网络虚拟化技术。在源网络设备与目的网络设备之间建立一条逻辑VXLAN隧道，采用媒体接入控制(media access control，MAC)地址封装于用户数据报协议(user datagram protocol，UDP)的封装方式，即，将虚拟机发出的原始以太报文完整的封装在UDP报文中，然后在外层使用物理网络的IP报文头和以太报文头封装，这样，封装后的报文就像普通IP报文一样，可以通过路由网络转发，使虚拟机彻底摆脱了二、三层网络的结构限制。
二层网关(layer2 gateway，L2GW)和三层网关(layer3 gateway，L3GW)：
为二层业务提供网络服务的网关称为二层网关，为三层业务提供网络服务的网关称为三层网关。二层业务指的是数据链路层的业务。三层业务指的是网络层的业务。其中，数据链路层为开放式系统互连(open system interconnect，OSI)模型的第二层，网络层为OSID模型的第三层。
请参阅图1a，图1a为集中式网关示意图。图1a中包括三层网关(L3GW)和两个二层网关、其中，二层网关包括作为边缘(edge)1节点的二层网关和作为edge 2节点的二层网关，三层网关作为边界(border)节点。在edge1节点中配置以太虚拟私有网实例(ethernet virtual private network instance，EVI)1，在edge2节点中提供EVI2。在三层网关中提供EVI1和EVI2。一套物理设备上可以配置多个相互隔离的EVI。每个EVI连接了一组或者多组用户网络。多个edge节点构成一个或者多个跨地域的二层网络，例如：主机1_11、主机1_12和主机2_11构成一个跨地域的二层网络，该二层网络中的主机地理位置不相同。EVI1中包括主机1_11和主机1_12，EVI2中包括主机2_11和主机2_12。
下面以VXLAN场景介绍二层网关与三层网关：
VXLAN网关分为二层网关和三层网关，VXLAN二层网关用于终端接入VXLAN网络，也可用于同一VXLAN网络的子网通信；VXLAN三层网关用于VXLAN网络中跨子网通信以及访问 外部网络。根据三层网关部署方式的不同，VXLAN三层网关又可以分为集中式网关和分布式网关。
当前一般使用基于三层网络虚拟化(network virtualization layer 3，NVO3)的VXLAN技术为园区提供大二层网络。运行NVO3的设备叫做网络虚拟边缘设备(network virtualization edge，NVE)，它位于叠加(overlay)网络的边界，实现二、三层的虚拟化功能。NVE以VXLAN隧道端点(vxlan tunnel endpoint，VTEP)进行标识，两个VTEP可以确定一条VXLAN隧道。换言之，VTEP用于标识VXLAN隧道的起点和终点。
基于前述图1a，请参阅图1b，图1b为VXLAN架构下集中式网关示意图。图1b中主机1_12和主机2_11同子网，两者之间的流量不需要经过L3GW，直接在L2GW之间二层转发即可，L2GW之间通过EVPN发布到达主机的媒体接入控制(media access control，MAC)路由。主机1_11和主机2_21跨子网，两者之间的流量需要经过L3GW三层转发，L3GW向L2GW发送的数据需要主机的地址解析协议(address resolution protocol，ARP)信息指导转发。
ARP协议：
ARP协议是用来将互联网协议(Internet protocol，IP)地址解析为MAC地址的协议。在局域网中，当网络设备(或者主机)有数据要发送给另一个网络设备(或主机)时，它必须知道对方的网络层地址(即IP地址)。但是仅有IP地址是不够的，因为IP数据报文必须封装成帧才能通过物理网络发送，因此发送方还必须有接收方的物理地址(MAC地址)，所以需要一个从IP地址到物理地址的映射。ARP就是实现这个功能的协议。具体的，通过ARP请求过程和ARP应答过程完成地址解析。
关于ARP请求过程，请参阅图2a，图2a为ARP请求过程的流程示意图。主机(host)A和HOSTB在同一网段，HOSTA要向HOSTB发送信息。首先，HOSTA查看自己的ARP表，确定其中是否包含有HOSTB对应的ARP表项。如果找到了HOSTB对应的MAC地址，则HOSTA直接利用ARP表中的MAC地址，对IP数据包进行帧封装，并将数据包发送给HOSTB。如果HOSTA在ARP表中找不到对应的MAC地址，则将缓存该数据报文，然后以广播方式发送一个ARP请求报文。ARP请求报文中的发送端IP地址和发送端MAC地址为HOSTA的IP地址和MAC地址，目标IP地址为HOSTB的IP地址，目标MAC地址为全0的MAC地址。由于ARP请求报文以广播方式发送，该网段上的所有主机都可以接收到该请求，但只有被请求的主机(即HOSTB)会对该请求进行处理。
关于ARP响应过程，请参阅图2b，图2b为ARP响应过程的流程示意图。HOSTB比较自己的IP地址和ARP请求报文中的目标IP地址，当两者相同时进行如下处理：将ARP请求报文中的发送端(即HOSTA)的IP地址和MAC地址存入自己的ARP表中。之后以单播方式发送ARP响应报文给HOSTA，其中包含了自己的MAC地址。HOSTB向HOSTA发出一个包含其MAC地址的ARP响应报文。HOSTA收到ARP响应报文后，将HOSTB的MAC地址加入到自己的ARP表中以用于后续报文的转发，同时将IP数据包进行封装后发送出去。
目前，园区网络等局域网网络中通常应用VXLAN技术。园区(campus)网络，通常是 指大学的校园网或企业的内部网。主要特征：园区网络中的网络设备(交换机，路由器等)以及传输媒介(光纤等)等通常园区网络所有者拥有，园区网络所有者例如是企业用户，大学或政府机构等。
申请人对VXLAN技术研究发现，应用VXLAN技术的园区网络较难实现新业务的拓展。并且，由于应用VXLAN技术的网络中报文转发是基于IP路由，造成应用VXLAN技术的园区网络无法针对用户的流量进行调优。
基于此，本申请实施例提出将SRv6技术应用于园区网络为例的局域网网络。由于SRv6技术具有可编程能力，因此可以提升园区网络的业务拓展能力，降低园区网络实现新业务的难度。并且，应用SRv6技术的园区网络还可以针对用户的流量进行调优，充分利用网络带宽资源。
请参阅图3a，图3a为本申请实施例提出的一种基于SRv6的通信方法30的实施例示意图。该基于SRv6的通信方法30可以应用于图1a所示的网络架构中。具体的，二层网关与三层网关之间基于SRv6实现通信交互。二层网关与三层网关之间通过EVPN type3路由和EVPN type2路由指导报文的转发。二层网关与三层网关之间交互的报文携带SRv6报文头。通过引入SRv6技术，使得园区网络等局域网网络具有流量工程能力。下面进行具体说明：
301、二层网关的EVI发布EVPN type3路由至三层网关。
步骤301中，以二层网关和三层网关分别部署EVPN实例的场景为例进行说明。首先，二层网关与三层网关之间部署边界网关协议(border gateway protocol，BGP)邻居关系。BGP邻居关系也称为BGP对等体(BGP peer)关系。A和B之间的BGP peer关系表示：A是B的BGP peer，并且B是A的BGP peer。具体的建立过程，请参阅请求评论(request for comments，RFC)7432协议的约定，此处不作赘述。
二层网关中部署(或者申请)一个或多个以太虚拟私有网示例(EVPN instance，EVI)，其中，每个EVI包括一个或多个主机，每个EVI通过连接一组或多组用户网络，构成一个或者多个跨地域的二层网络。与二层网关类似，三层网关中部署(或者申请)一个或多个EVI。
二层网关的EVI发布(或者通告)EVPN type3路由也称为集成多播路由(inclusive multicast route)，EVPN type3路由用于指导广播&未知单播&组播(broadcast&unknown-unicast&multicast，BUM)流量的转发。
示例性的，二层网关的EVI所发布的EVPN type3路由的各个字段如表1所示：
表1
Figure PCTCN2022106169-appb-000001
其中，Ethernet Tag ID和Originating Router‘s IP Address作为前缀索引。在BGP段标识前缀(BGP Prefix Segment Identifier，BGP Prefix-SID)属性中携带EVI在二层网关申请的SID，该SID为end.dt2m类型的SID。end.dt2m类型的SID具有解封装和L2表现的端点“Endpoint with decapsulation and L2 table。示例性的，end.dt2m类型的SID用于单播或多播(BUM)的用例“Unicast and Multicast(BUM)use case with”或者过滤以太网段标识符(ESI)“Ethernet Segment Identifier(ESI)filtering”。
302、三层网关的EVI发布EVPN type3路由至二层网关。
步骤302中，三层网关所发布的EVPN type3路由与步骤301中二层网关所发布的EVPN type3路由类似，该EVPN type3路由的BGP Prefix-SID属性中携带EVI在三层网关申请的SID，该SID为end.dt2m类型的SID。
303、二层网关发布EVPN type2路由至三层网关。
步骤303中，二层网关在转发面学习主机的MAC地址后，通过EVPN EVPN type2路由将该MAC地址发布至三层网关，该主机为二层网关中部署的EVI中的主机。EVPN type2路由又称为MAC/IP发布路由(MAC/IP advertisement route)，用于发布主机的MAC地址或MAC+地址和IP地址的信息。三层网关接收该EVPN type2路由后，生成MAC转发表。该EVPN type2路由用于指导单播流量转发。
示例性的，该EVPN type2路由的各个字段如表2所示：
表2
字段名 长度(字节长度/octet)
路由标识(Route Distinguisher，RD) 8octets
以太网段标识符(Ethernet segment identifier，ESI) 10octets
以太网标签标识(Ethernet Tag ID) 4octets
MAC地址长度(MAC Address Length) 1octet
MAC地址(MAC Address) 6octets
IP地址长度(IP Address Length) 1octet
IP地址(IP Address) 4 or 16octets
多协议标签交换标签(MPLS Label) 3octets
多协议标签交换标签2(MPLS Label) 0 or 3octets
EVPN type2路由中，前缀索引包括：Ethernet Tag ID、MAC Address、IP Address。ESI和MPLS Label作为路由属性。在EVPN type2路由中,BGP Prefix-SID属性中携带EVI在二层网关申请的SID，该SID为end.dt2u类型的SID。end.dt2u类型的SID具有解封装和单播MAC的端点“Endpoint with decapsulation and unicast MAC”。示例性的，end.dt2u类型的SID用于EVPN桥接单播用例“EVPN Bridging Unicast use case”。
三层网关收到该EVPN type2路由后，实现三层网关与二层网关之间单播流量可达。
需要说明的是，步骤301-302与步骤303之间的顺序此处不作限制，既可以先执行步骤301-302，后执行步骤303；也可以先执行步骤303，后执行步骤301-302。
304、二层网关向三层网关发送ARP请求报文。
步骤304中，二层网关向三层网关发送APR请求报文，为了便于理解，请参阅图3b，图3b为本申请实施例中ARP报文交互示意图。以二层网关中的主机包括主机1_11和主机1_12为例进行说明。
首先，主机1_11生成ARP请求报文并将该ARP请求报文发送至二层网关，本申请实施例中为了便于区分，将主机向二层网关发送的ARP请求报文称为第一ARP请求报文。
示例性的，该第一ARP请求报文的结构如图3c所示，图3c为本申请实施例中ARP请求报文或者ARP响应报文结构示意图。ARP请求报文包括以下字段：目的MAC地址(DMAC)、源MAC地址(SMAC)、帧类型，ARP请求或者ARP回应。其中，ARP请求或者ARP回应字段中包括以下字段：目的MAC地址、源MAC地址、帧类型、MAC地址类型、IP协议类型、MAC地址长度、IP地址长度、OP、发送端MAC地址、发送端IP地址、目的MAC地址和目的IP地址。下面分别进行介绍：
目的MAC地址：6个字节长度。当该报文为ARP请求报文时，目的MAC地址为广播的MAC地址(0xFF.FF.FF.FF.FF.FF)。
源MAC地址：6个字节长度。
帧类型：2个字节长度，该字段的值为0x0806。
MAC地址类型：2个字节长度，定义运行ARP网络的地址类型。值为1，即表示以太网地址。
IP协议类型：2个字节长度，定义协议的类型。值为0x0800，即表示IP地址。
MAC地址长度：1个字节长度，定义以字节为单位的物理地址的长度。对于ARP请求报文或者ARP回应报文，该值为6。
IP地址长度：1个字节长度，定义以字节为单位的逻辑地址的长度。对于ARP请求报文或者ARP回应报文，该值为4。
OP字段：2个字节长度，定义ARP报文类型，当OP字段值为1，则该报文为ARP请求报文；当OP字段值为2，则该报文为ARP响应报文。
发送端MAC地址：6个字节长度，定义发送站的MAC地址。
发送端IP地址：4个字节长度，定义发送站的IP地址。
目的MAC地址：6个字节长度。当该报文为ARP请求报文时，该字段的值为0。
目的IP地址：4个字节长度。
其次，二层网关收到来自主机1_11的第一ARP请求报文后，基于该第一ARP请求报文封装SEV6报文头，生成第二ARP请求报文。该第二ARP请求报文的报文净荷(payload)为第一ARP请求报文。该第二ARP请求报文可以理解是一种SRv6报文。示例性的，下面以第二ARP请求报文是SRv6BE报文为例进行说明，请参阅图3d，图3d为本申请实施例中一种SRv6BE报文结构示意图。SEV6BE报文包括以下字段：版本(version)、流量分类(traffic class)、流标签(flow label)、有效载荷的长度(payload length)、下一个标题(next header)、最大跳数(hop limit)、源地址(source address)和目的地址(destination address)。其中，版本(version)字段指示SEV6BE报文的IP版本，该字段值为6；流量分类(traffic class)字段与IPV4包头的服务类型(TOS)字段类似； 流标签(flow label)用于标记IPV6数据包的一个流；下一个标题(next header)字段，该字段值为143；最大跳数(hop limit)字段定义IP数据包能经过的最大跳数，每跳一次该字段的值减1；源地址(source address)字段为IP数据包的源地址；目的地址(destination address)为IP数据包的目的地址。
以图3b示意的场景为例，第二ARP请求报文中目的地址字段的字段值为三层网关发布的end.dt2m类型的sid。第二ARP响应报文中目的地址字段的字段值为二层网关发布的end.dt2u类型的sid。第二ARP请求报文中的目的地址字段，也可以理解为第二ARP请求报文的SRv6报文头中的目的地址字段；第二ARP响应报文中的目的地址字段，也可以理解为第二ARP响应报文的SRv6报文头中的目的地址字段。
305、三层网关向二层网关发送ARP响应报文。
步骤305中，三层网关收到来自二层网关的第二ARP请求报文后，剥掉该第二ARP请求报文的SRv6报文头，获取第一ARP请求报文。然后，三层网关将第一ARP请求报文发送至控制面，进行ARP学习。
当上述流程结束后，三层网关向二层网关发送ARP响应报文。结合图3b的示例，本申请实施例中，将三层网关向二层网关发送的ARP响应报文称为第一ARP响应报文。该第一ARP响应报文是三层网关基于第二ARP响应报文封装SRv6报文头后得到的，第二ARP响应报文作为第一ARP响应报文的有效负载。
二层网关收到来自三层网关的第一ARP响应报文后，剥掉SRv6报文头，获取第二ARP响应报文。然后，二层网关向主机1_11发送该第二ARP响应报文。主机1_11收到第二ARP响应报文后，进行ARP学习。
通过上述流程，完成二层网关与三层网关之间建立报文传输的流程。二层网关与三层网关之间可以交互数据报文，该数据报文携带SRv6报文头。数据报文中的SRv6报文头与ARP报文(包括ARP请求报文和ARP响应报文)的SRv6报文头类似，此处不作赘述。
在应用该基于SRv6的通信方法300的园区网络中，可以通过多种手段实现流量调优，下面进行示例说明，可以理解的是，本申请实施例中对流量调优的手段不作限制。
示例性的，园区网络中除了二层网关与三层网关外，还包括控制器。二层网关与三层网关通过双向主动测量协议(Two-Way Active Measurement Protocol，TWAMP)检测路径时延，并将检测结果(即路径时延)通报给控制器。控制器基于检测结果(即路径时延)计算满足服务等级协议(service level agreement,SLA)的路径，并确定该路径的SRv6路径信息。控制器将该路径的SRv6路径信息下发给二层网关或者三层网关。二层网关或者三层网关将该路径的SRv6路径信息导入到SRv6策略(policy)，并按照控制器计算的路径转发报文，以满足SLA要求。二层网关和/或三层网关使用TWAMP检测路径时延，并通过遥测(Telemetry)技术上报至控制器，当控制器发现路径的时域劣化时，控制器重新计算新的路径，以保证新的路径满足SLA要求。
本申请实施例中，通过上述方法使得园区网络等具有二层网关和三层网关的局域网网络可以成功应用SRv6技术。使得园区网络可以针对用户的流量进行调优，提升网络带宽的利用率。同时SRv6技术具有可编程的优点，因此可以有效降低园区网络的实现新业务难度。 通过引入SRv6技术，使得园区网络具有流量工程能力，因此可以有效平衡园区网络中各个网关的业务，避免网络带宽的浪费。流量工程是指网络节点可以根据网络中的有效资源建立数据的转发路径，并具有为关键流量预留网络带宽的能力。通过动态监控网络的流量和网元的负载，实时调整流量管理参数、路由参数和资源约束参数等，优化网络资源的使用，避免负载不均导致的拥塞。
结合图3a所示的实施例，申请人发现而当SRv6技术应用于园区网络中时，三层网关(layer3 gateway，L3GW)需要存储并管理各个主机的媒体接入控制(media access control，MAC)地址，这些主机为与该三层网关存在通信连接的所有二层网关(layer2 gateway，L2GW)下辖的主机。随着网络容量的增大，三层网关需要存储并管理的主机的MAC地址越来越多，造成三层网关的MAC路由压力增大。受限于三层网关的设备性能，影响了网络扩容。
基于此，本申请实施例提出的一种基于SRv6的通信方法，三层网关中不再存储主机的MAC地址，并且三层网关可以通过多种手段获取出接口，该出接口用于指示所述三层网关向所述二层网关发送响应报文的路径。在保障三层网关与二层网关之间建立通信连接的前提下，有效降低三层网关的MAC路由压力，在较低成本下可以实现网络扩容。
可以理解的是，图4或图5示意的实施例，可以支持SRv6BE技术，也可以支持SRv6policy技术，此处不作限制。
具体的，三层网关可以通过控制面获取出接口，三层网关也可以通过转发面获取出接口。下面分别结合附图进行说明，首先介绍三层网关通过控制面获取出接口。
请参阅图4，图4为本申请实施例提出的一种基于SRv6的通信方法40的实施例示意图。本申请实施例提出的一种基于SRv6的通信方法40包括：
400、二层网关关闭发布EVI中主机MAC路由的功能。
步骤400中，二层网关关闭向三层网关发布EVI中主机MAC路由，该主机为二层网关中部署(或者配置)的以太虚拟私有网示例(EVPN instance，EVI)中的主机。例如EVI中的主机。
默认状态下，二层网关向三层网关发布EVI中主机MAC路由。当二层网关使能关闭向三层网关发布EVI中主机MAC路由后，二层网关生成的MAC路由中不包括主机的MAC地址，该MAC路由的目的地是三层网关。通过关闭二层网关发布EVI中主机MAC路由的功能，使得三层网关不会收到二层网关中各主机的MAC地址，进而避免三层网关保存该主机的MAC地址，降低三层网关的MAC路由压力。可以理解的是，二层网关也可以通过配置的方式实现不再向三层网关发送主机的MAC地址，此处不作限制。
需要说明的是，步骤400为可选步骤。当步骤400不执行时，二层网关可以向三层网关发布MAC路由，该MAC路由包括EVI中各主机的MAC地址。此时，三层网关收到该MAC路由后，不保存该EVI中各主机的MAC地址。
401、二层网关生成EVI-MAC路由。
步骤401中，首先二层网关与三层网关之间通过边界网关协议(border gateway protocol，BGP)建立以太虚拟私有网(ethernet virtual private network，EVPN)邻居， 具体的建立过程，请参阅请求评论(request for comments，RFC)7432协议的约定，此处不作赘述。
本申请实施例中，以二层网关中包括一个以太虚拟私有网示例为例，该EVI中包括一个或多个主机。可以理解的是，二层网关还可以包括多个EVI，此处不作限制。
当二层网关与三层网关建立EVPN邻居后，二层网关生成MAC路由，该MAC路由包括EVI在二层网关申请的段标识(segment identifier，SID)。本申请实施例中为了便于描述，将该EVI申请的SID称为EVI SID。该EVI SID为end.dt2u类型的SID。将该MAC路由称为EVI-MAC路由。
一种可能的实现方式中，该EVI-MAC路由的类型为EVPN type2路由。
需要说明的是，对于同一个EVI，在不同的网关设备中申请的SID是不同的，例如：以EVI1为例进行说明，EVI1在二层网关中申请的SID为EVI SID-1，EVI1在三层网关中申请的SID为EVI SID-2。
又例如：以图7所示的场景为例，图7为本申请实施例提出的一种应用场景示意图，图7中二层网关包括edge1节点和edge2节点，其中，edge1节点包括EVI1，edge2节点包括EVI1和EVI2。二层网关与三层网关之间建立SRv6隧道，edge1节点与edge2节点之间建立SRv6隧道。三层网关包括EVI1和EVI2。则EVI1在edge1节点申请的SID与EVI1在edge2节点申请的SID不一致。
该EVI-MAC路由中携带的MAC地址不包括该EVI中各主机的MAC地址。
可选的，该EVI-MAC路由中携带的MAC地址可以是该二层网关的MAC地址。
可选的，该EVI-MAC路由中携带的MAC地址还可以是全F的MAC地址，该全F的MAC地址又称为字段值为全F的MAC地址。示例性的，该MAC路由中路由前缀的MAC地址的字段值为“0xffffffffffff”。可以理解的是，EVI-MAC路由中携带的MAC地址还可以是其它的字段值，此处不作限制。
可选的，该EVI-MAC路由中还包括指示信息，该指示信息指示三层网关收到该EVI-MAC路由后，避免将EVI-MAC路由下发到转发面的MAC转发表(forwarding table)。MAC转发表记录MAC地址与出接口的映射关系。
可选的，该EVI-MAC路由中还可以包括拓展团体属性(extended community)，该拓展团体属性用于承载前述的指示信息。则三层网关收到该EVI-MAC路由后，根据该EVI-MAC路由的拓展团体属性(该拓展团体属性中承载该指示信息)，避免将EVI-MAC路由下发到转发面的MAC转发表。
可选的，该指示信息可以是该拓展团体属性，即该拓展团体属性用于指示三层网关避免将EVI-MAC路由下发到转发面的MAC转发表。
示例性的，该拓展团体属性如图6所示，图6为本申请实施例提出的一种拓展团体属性的示意图。该拓展团体属性包括：类型(Type)，tpye字段的值为0x06，表示该第展团体属性的类型为EVPN；子类型(sub-type)，sub-type字段的值为＝0x？，标识该拓展团体属性的类型为拓展团体属性“DEFAULT-MAC Extended Community”；标记(flags)字段占用空间1字节，当前未使用；预留(reserved)字段的值为0。
示例性的，该EVI-MAC路由如表3所示：
表3
Figure PCTCN2022106169-appb-000002
402、二层网关向三层网关发布EVI-MAC路由。
步骤402中，当二层网关生成EVI-MAC路由后，二层网关向三层网关发布该EVI-MAC路由。具体的，二层网关通过IP报文向三层网关发布该EVI-MAC路由。
403、三层网关根据EVI-MAC路由中的EVI SID确定出接口。
步骤403中，当三层网关接收EVI-MAC路由后，根据该EVI-MAC路由携带的MAC地址(该MAC地址为二层网关的MAC地址，或者，为全F的MAC地址)，确定需要根据该EVI-MAC路由携带的EVI SID查找出接口。出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。
可以理解的是，三层网关也可以根据该EVI-MAC路由中包括的扩展团体属性确定需要根据该EVI-MAC路由携带的EVI SID查找出接口，此处不作限制。
三层网关根据该EVI-MAC路由中的EVI SID作为目的IP(destination IP，DIP)地址，在转发面查找路由表(routing table)，确定出接口。该路由表又称为路由信息表(routing information table)或者路由信息库(routing information base，RIB)。
具体的，路由表可以理解为一组或多组键值对(key-value)，三层网关将EVI SID作为key，在路由表中查找对应的value，该value为出接口。
本申请实施例中，以图7示意的场景为例，三层网关中路由表如表4所示：
表4
Figure PCTCN2022106169-appb-000003
图7为本申请实施例提出的一种应用场景示意图，图7中二层网关包括edge1节点和edge2节点，其中，edge1节点包括EVI1，edge2节点包括EVI1和EVI2。二层网关与三层网关之间建立SRv6隧道，edge1节点与edge2节点之间建立SRv6隧道。三层网关包括EVI1和EVI2。
三层网关根据EVI SID作为DIP，查找路由表(如表4示例)，确定出接口为“0001”。示例性的，三层网关根据该出接口确定ARP响应报文的路径。
404、二层网关向三层网关发送ARP请求报文。
步骤404中，二层网关接收二层网关中EVI的主机的ARP请求报文，本申请实施例中为了便于区分，将主机发送至二层网关的ARP请求报文称为第一ARP请求报文。以图7示意的场景为例，例如二层网关(edge1节点)接收主机1_11的第一ARP请求报文。二层网关基于来自主机1_11的第一ARP请求报文封装SRv6报文头，得到携带SRv6报文头的ARP请求报文，本申请实施例中将该携带SRv6报文头的ARP请求报文称为第二ARP请求报文。该SRv6报文头中SIP为EVI SID。
该第二ARP请求报文的DIP为三层网关的SID，该三层网关的SID为二层网关与三层网关建立EVPN邻居时由三层网关发布的，该三层网关的SID为end.dt2m类型的SID。
可选的，该第二ARP请求报文的源IP(source IP，SIP)地址为EVI SID，该EVI SID为EVI在二层网关中申请的SID，该EVI SID为end.dt2u类型的SID。第一ARP请求报文作为第二ARP请求报文的报文净荷(payload)。
405、三层网关向二层网关发送ARP响应报文。
步骤405中，三层网关接收来自二层网关的第二ARP请求报文后，根据第二ARP请求报文的报文净荷(第一ARP请求报文)学习ARP信息，该ARP信息用于指示三层网关向二层网关中的主机发送ARP响应报文。具体的，该APR信息可以包括主机的MAC地址与主机的IP地址。
三层网关将第二ARP请求报文的SIP作为ARP响应报文的DIP，该ARP响应报文的SIP为EVI在三层网关中申请的SID，该EVI在三层网关中申请的SID为end.dt2u类型的SID。
三层网关根据步骤404中确定的出接口，通过三层网关与二层网关之间的SRv6隧道向二层网关发送该ARP响应报文。二层网关接收该ARP响应报文后，终结与三层网关之间的SRv6隧道并将ARP响应报文转发至EVI的主机(例如主机1_11)。
具体的，三层网关向二层网关发送第二ARP响应报文，该第二ARP响应报文包括SRv6报文头和第一ARP响应报文，第一ARP响应报文作为第二ARP响应报文的有效载荷。二层网关收到第二ARP响应报文后，剥去SRv6报文头，并将第一ARP响应报文转发至EVI的主机。
通过上述流程，三层网关学习关于EVI的主机的ARP信息，二层网关中EVI的主机学习三层网关的ARP信息，二层网关中EVI的主机与三层网关之间实现三层转发可达。
本申请实施例中，二层网关向三层网关发送EVI-MAC路由，该EVI-MAC路由包括二层网关中EVI申请的EVI SID。三层网关根据该EVI SID确定出接口，该出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。由于二层网关不再向三层网关发送二层网关中EVI的主机的MAC地址，有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。
其次，介绍三层网关通过转发面获取出接口。
请参阅图5，图5为本申请实施例提出的一种基于SRv6的通信方法50的实施例示意图。本申请实施例提出的一种基于SRv6的通信方法50包括：
500、二层网关关闭发布EVI中主机MAC路由的功能。
步骤500与前述步骤400一致，此处不作赘述。
501、二层网关生成EVI-MAC路由。
502、二层网关向三层网关发布EVI-MAC路由。
步骤501-502与前述步骤401-402类似，此处不作赘述。
需要说明的是步骤501-502为可选步骤，即步骤501-502可以不执行，当步骤501-502不执行时(即二层网关不向三层网关发送MAC路由)，步骤500后执行步骤503。
503、二层网关向三层网关发送ARP请求报文。
步骤503与步骤404类似，二层网关接收二层网关中EVI的主机的ARP请求报文，本申请实施例中为了便于区分，将主机发送至二层网关的ARP请求报文称为第一ARP请求报文。以图7示意的场景为例，例如二层网关(edge1节点)接收主机1_11的第一ARP请求报文。二层网关基于来自主机1_11的第一ARP请求报文封装SRv6报文头，得到携带SRv6报文头的ARP请求报文，本申请实施例中将该携带SRv6报文头的ARP请求报文称为第二ARP请求报文。
该第二ARP请求报文的DIP为三层网关的SID，该三层网关的SID为二层网关与三层网关建立EVPN邻居时由三层网关发布的，该三层网关的SID为end.dt2m类型的SID。该第二ARP请求报文的SIP为EVI SID，该EVI SID为EVI在二层网关中申请的SID，该EVI SID为end.dt2u类型的SID。第一ARP请求报文作为第二ARP请求报文的报文净荷(payload)。
504、三层网关根据ARP请求报文中的EVI SID确定出接口。
步骤504中，三层网关根据ARP请求报文中的EVI SID，在转发面查找转发信息表(forwarding information table)，确定出接口。该转发信息表的来源为三层网关的控制面学习路由表后发布至转发面。转发信息表又称为转发表，或者转发信息库(forwarding information base，FIB)。出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。
该转发信息表的具体内容与表4示意的路由表类似。具体的，将该转发信息表可以理解为一组或多组键值对(key-value)，三层网关将EVI SID作为key，在该转发信息表中查找对应的value，该value为出接口。
三层网关根据EVI SID作为DIP，查找转发信息表，确定出接口为“0001”。示例性的，三层网关根据该出接口确定ARP响应报文的路径。
505、三层网关向二层网关发送ARP响应报文。
步骤505与前述步骤405类似，三层网关接收来自二层网关的第二ARP请求报文后，根据第二ARP请求报文的报文净荷(第一ARP请求报文)学习ARP信息，该ARP信息用于指示三层网关向二层网关中的主机发送ARP响应报文。具体的，该APR信息可以包括主机的MAC地址与主机的IP地址。
三层网关将第二ARP请求报文的SIP作为ARP响应报文的DIP，该ARP响应报文的SIP为EVI在三层网关中申请的SID，该EVI在三层网关中申请的SID为end.dt2u类型的SID。
三层网关根据步骤504中确定的出接口，通过三层网关与二层网关之间的SRv6隧道向 二层网关发送该ARP响应报文。二层网关接收该ARP响应报文后，终结与三层网关之间的SRv6隧道并将ARP响应报文转发至EVI的主机(例如主机1_11)。
具体的，三层网关向二层网关发送第二ARP响应报文，该第二ARP响应报文包括SRv6报文头和第一ARP响应报文，第一ARP响应报文作为第二ARP响应报文的有效载荷。二层网关收到第二ARP响应报文后，剥去SRv6报文头，并将第一ARP响应报文转发至EVI的主机。
通过上述流程，三层网关学习关于EVI的主机的ARP信息，二层网关中EVI的主机学习三层网关的ARP信息，二层网关中EVI的主机与三层网关之间实现三层转发可达。
本申请实施例中，二层网关向三层网关发送的ARP请求报文中携带EVI SID，该EVI SID为EVI的SID。三层网关根据该EVI SID确定出接口，该出接口被三层网关用于向二层网关发送目的地址为EVI SID的报文。由于二层网关不再向三层网关发送二层网关中EVI的主机的MAC地址，有效降低三层网关的MAC路由压力。使得三层网关可以支持与更多的主机建立通信连接，有效扩大网络容量。
上述主要以方法的角度对本申请实施例提供的方案进行了介绍。可以理解的是，网络设备为了实现上述功能，其包含了执行各个功能相应的硬件结构和/或软件模块。本领域技术人员应该很容易意识到，结合本文中所公开的实施例描述的各示例的模块及算法步骤，本申请能够以硬件或硬件和计算机软件的结合形式来实现。某个功能究竟以硬件还是计算机软件驱动硬件的方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本申请的范围。
本申请实施例可以根据上述方法示例对网络设备进行功能模块的划分，例如，可以对应各个功能划分各个功能模块，也可以将两个或两个以上的功能集成在一个处理模块中。上述集成的模块既可以采用硬件的形式实现，也可以采用软件功能模块的形式实现。需要说明的是，本申请实施例中对模块的划分是示意性的，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式。
以下介绍本申请实施例的网络设备，以下介绍的网络设备具有上述方法实施例中的二层网关或三层网关的任意功能。
图8为本申请实施例提供的一种网络设备800的结构示意图，如图8所示，网络设备800包括：收发模块801，用于执行步骤402、404或405；处理模块802，用于执行步骤400、401或403。
又例如，收发模块801，用于执行步骤502、503或505；处理模块802，用于执行步骤500、501或504。
又例如，收发模块801与处理模块802，用于执行步骤301-305。
网络设备800可以对应于上述方法实施例中的二层网关、三层网关，网络设备800中的各单元和上述其他操作和/或功能分别为了实现方法实施例中的二层网关、三层网关或控制器所实施的各种步骤和方法，具体细节可参见上述方法实施例，为了简洁，在此不再赘述。
网络设备800在处理报文时，仅以上述各功能模块的划分进行举例说明，实际应用中，可以根据需要而将上述功能分配由不同的功能模块完成，即将网络设备800的内部结构划分成不同的功能模块，以完成以上描述的全部或者部分功能。另外，上述实施例提供的网络设备800与上述图3a、图4或图5对应的实施例方法属于同一构思，其具体实现过程详见上述方法实施例，这里不再赘述。
为了实现上述实施例，本申请还提供了一种网络设备。可以参阅图9，图9为本申请实施例提供的一种网络设备900的结构示意图。
图9所示的网络设备900尽管示出了某些特定特征，但是本领域的技术人员将从本申请实施例中意识到，为了简洁起见，图9未示出各种其他特征，以免混淆本申请实施例所公开的实施方式的更多相关方面。为此，作为示例，在一些实现方式中，网络设备900包括一个或多个处理单元(如，CPU)901、网络接口902、编程接口903、存储器904和一个或多个通信总线905，用于将各种组件互连。在另一些实现方式中，网络设备900也可以在上述示例基础上省略或增加部分功能部件或单元。
在一些实现方式中，网络接口902用于在网络系统中和一个或多个其他的网络设备/服务器连接。在一些实现方式中，通信总线905包括互连和控制系统组件之间的通信的电路。存储器904可以包括非易失性存储器，例如，只读存储器(read-only memory，ROM)、可编程只读存储器(programmable ROM，PROM)、可擦除可编程只读存储器(erasable PROM，EPROM)、电可擦除可编程只读存储器(electrically EPROM，EEPROM)或闪存。存储器904也可以包括易失性存储器，易失性存储器可以是随机存取存储器(random access memory，RAM)，其用作外部高速缓存。
在一些实现中，存储器904或存储器904的非暂时性计算机可读存储介质存储以下程序、模块和数据结构，或其子集，例如包括收发单元(图中未示出)、获取单元9041和处理单元9042。
在一个可能的实施例中，该网络设备900可以具有上述图3a、图4或图5对应的方法实施例中的二层网关或三层网关中的任意功能。
应理解，网络设备900对应于上述方法实施例中的二层网关、三层网关或控制器，网络设备900中的各模块和上述其他操作和/或功能分别为了实现上述方法实施例中的二层网关、三层网关或控制器所实施的各种步骤和方法，具体细节可参见上述图3a、图4或图5对应的方法实施例，为了简洁，在此不再赘述。
应理解，本申请可以是由网络设备900上的网络接口902来完成数据的收发操作，也可以是由处理器调用存储器中的程序代码，并在需要时配合网络接口902来实现收发单元的功能。
在各种实现中，网络设备900用于执行本申请实施例提供的基于SRv6的通信方法，例如是执行上述图3a、图4或图5所示的实施例所对应的基于SRv6的通信方法。
本申请图9所述的网络设备具体结构可以为图10所示。
图10为本申请实施例提供的一种网络设备1000的结构示意图，网络设备1000包括： 主控板1010和接口板1030。
主控板1010也称为主处理单元(main processing unit，MPU)或路由处理器(route processor)，主控板1010用于对网络设备1000中各个组件的控制和管理，包括路由计算、设备管理、设备维护、协议处理功能。主控板1010包括：中央处理器1011和存储器1012。
接口板1030也称为线路处理单元(line processing unit，LPU)、线卡(line card)或业务板。接口板1030用于提供各种业务接口并实现数据包的转发。业务接口包括但不限于以太网接口、POS(Packet over SONET/SDH)接口等。接口板1030包括：中央处理器1031、网络处理器1032、转发表项存储器1034和物理接口卡(physical interface card，PIC)1033。
接口板1030上的中央处理器1031用于对接口板1030进行控制管理并与主控板1010上的中央处理器1011通信。
网络处理器1032用于实现报文的转发处理。网络处理器1032的形态可以是转发芯片。
物理接口卡1033用于实现物理层的对接功能，原始的流量由此进入接口板1030，以及处理后的报文从该物理接口卡1033发出。物理接口卡1033包括至少一个物理接口，物理接口也称物理口，物理接口可以为灵活以太(Flexible Ethernet,FlexE)物理接口。物理接口卡1033也称为子卡，可安装在接口板1030上，负责将光电信号转换为报文并对报文进行合法性检查后转发给网络处理器1032处理。在一些实施例中，接口板1030的中央处理器1031也可执行网络处理器1032的功能，比如基于通用CPU实现软件转发，从而接口板1030中不需要网络处理器1032。
可选的，网络设备1000包括多个接口板，例如网络设备1000还包括接口板1040，接口板1040包括：中央处理器1041、网络处理器1042、转发表项存储器1044和物理接口卡1043。
可选的，网络设备1000还包括交换网板1020。交换网板1020也可以称为交换网板单元(switch fabric unit，SFU)。在网络设备有多个接口板1030的情况下，交换网板1020用于完成各接口板之间的数据交换。例如，接口板1030和接口板1040之间可以通过交换网板1020通信。
主控板1010和接口板耦合。例如，主控板1010、接口板1030和接口板1040，以及交换网板1020之间通过系统总线和/或系统背板相连实现互通。在一种可能的实现方式中，主控板1010和接口板1030之间建立进程间通信协议(inter-process communication，IPC)通道，主控板1010和接口板1030之间通过IPC通道进行通信。
在逻辑上，网络设备1000包括控制面和转发面，控制面包括主控板1010和中央处理器1031，转发面包括执行转发的各个组件，比如转发表项存储器1034、物理接口卡1033和网络处理器1032。控制面执行发布路由、生成转发表、处理信令和协议报文、配置与维护设备的状态等功能，控制面将生成的转发表下发给转发面，在转发面，网络处理器1032基于控制面下发的转发表对物理接口卡1033收到的报文查表转发。控制面下发的转发表可以保存在转发表项存储器1034中。在有些实施例中，控制面和转发面可以完全分离，不在同一设备上。
应理解，网络设备900中的收发单元可以相当于网络设备1000中的物理接口卡1033或物理接口卡1043；网络设备900中的获取单元9041和处理单元9042可以相当于网络设备1000中的中央处理器1011或中央处理器1031，也可以相当于存储器1012中存储的程序代码或指令。
应理解，本申请实施例中接口板1040上的操作与接口板1030的操作一致，为了简洁，不再赘述。应理解，本实施例的网络设备1000可对应于上述各个方法实施例中的二层网关或三层网关，该网络设备1000中的主控板1010、接口板1030和/或接口板1040可以实现上述各个方法实施例中的二层网关或三层网关所具有的功能和/或所实施的各种步骤，为了简洁，在此不再赘述。
值得说明的是，主控板可能有一块或多块，有多块的时候可以包括主用主控板和备用主控板。接口板可能有一块或多块，网络设备的数据处理能力越强，提供的接口板越多。接口板上的物理接口卡也可以有一块或多块。交换网板可能没有，也可能有一块或多块，有多块的时候可以共同实现负荷分担冗余备份。在集中式转发架构下，网络设备可以不需要交换网板，接口板承担整个系统的业务数据的处理功能。在分布式转发架构下，网络设备可以有至少一块交换网板，通过交换网板实现多块接口板之间的数据交换，提供大容量的数据交换和处理能力。可选的，网络设备的形态也可以是只有一块板卡，即没有交换网板，接口板和主控板的功能集成在该一块板卡上，此时接口板上的中央处理器和主控板上的中央处理器在该一块板卡上可以合并为一个中央处理器，执行两者叠加后的功能。具体采用哪种架构，取决于具体的组网部署场景，此处不做唯一限定。
在一些可能的实施例中，上述第一网络设备可以实现为虚拟化设备。虚拟化设备可以是运行有用于发送报文功能的程序的虚拟机(virtual machine，VM)，虚拟路由器或虚拟交换机。虚拟化设备部署在硬件设备上(例如，物理服务器)。例如，可以基于通用的物理服务器结合网络功能虚拟化(network functions virtualization，NFV)技术来实现第一网络设备。
应理解，上述各种产品形态的网络设备，分别具有上述方法实施例中二层网关或三层网关的任意功能，此处不再赘述。
本申请实施例还提供的一种计算机可读存储介质，包括指令，当其在计算机上运行时，使得计算机控制网络装置执行如前述方法实施例所示任一项实现方式。
本申请实施例还提供的一种计算机程序产品，计算机程序产品包括计算机程序代码，当计算机程序代码在计算机上运行时，使得计算机执行如前述方法实施例所示任一项实现方式。
进一步地，本申请实施例还提供了一种计算机程序产品，当该计算机程序产品在网络设备上运行时，使得网络设备执行上述图3a、图4或图5对应的方法实施例中二层网关、三层网关或控制器执行的方法。
本申请实施例还提供了一种芯片系统，包括处理器和接口电路，接口电路，用于接收指令并传输至处理器。其中，所述处理器用于实现上述任一方法实施例中的方法。
可选的，该芯片系统还包括存储器，该芯片系统中的处理器可以为一个或多个。该处 理器可以通过硬件实现也可以通过软件实现。当通过硬件实现时，该处理器可以是逻辑电路、集成电路等。当通过软件实现时，该处理器可以是一个通用处理器，通过读取存储器中存储的软件代码来实现上述任一方法实施例中的方法。
可选的，该芯片系统中的存储器也可以为一个或多个。该存储器可以与处理器集成在一起，也可以和处理器分离设置，本申请并不限定。示例性的，存储器可以是非瞬时性处理器，例如只读存储器ROM，其可以与处理器集成在同一块芯片上，也可以分别设置在不同的芯片上，本申请对存储器的类型，以及存储器与处理器的设置方式不作具体限定。
请参阅图11，图11为本申请实施例提出的一种网络系统1100示意图。该网络系统1100包括：二层网关1101和三层网关1102。二层网关1101和三层网关1102例如可以为路由器、交换机或网关等物理设备，也可以是支持路由发布和报文转发的虚拟设备等。本实施例对二层网关1101和三层网关1102的具体类型不做限定。
可选的，该网络系统1100还包括控制器1103，控制器1103可以是管理上述二层网关1101和三层网关1102的服务器。可选的，二层网关1101可以是网络设备800、网络设备900或者网络设备1000。可选的，三层网关1102可以是网络设备800、网络设备900或者网络设备1000。可选的，控制器1103可以是网络设备800、网络设备900或者网络设备1000。
请参阅图12，图12为本申请实施例提出的一种网络系统1200示意图。该网络系统1200包括：第一网络设备1201、第二网络设备1202和第三网络设备1203。第一网络设备1201、第二网络设备1202和第三网络设备1203例如可以为路由器、交换机或网关等物理设备，也可以是支持路由发布和报文转发的虚拟设备等。本实施例对第一网络设备1201、第二网络设备1202和第三网络设备1203的具体类型不做限定。
示例性的，网络系统1200应用于图1a所示的场景时，该第一网络设备1201可以为L3GW，该第二网络设备1202可以是edge1(L2GW)，该第三网络设备1203可以是edge2(L2GW)。
可选的，图12示意的网络系统1200中还包括控制器1204。控制器1204在图1b所示的场景中未示出。
一种可能的实现方式中，第二网络设备1202和/或第三网络设备1203生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述第二网络设备1202和/或第三网络设备1203申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
第二网络设备1202和/或第三网络设备1203向第一网络设备1201发布所述EVI-MAC路由；
第一网络设备1201接收第二网络设备1202和/或第三网络设备1203通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述第二网络设备1202和/或第三网络设备 1203申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
第一网络设备1201根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被所述第一网络设备1201用于向所述第二网络设备1202和/或第三网络设备1203发送目的地址为所述EVI SID的报文。
在另一种可能的实现方式中，第二网络设备1202和/或第三网络设备1203向第一网络设备1201发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID为所述第二网络设备1202和/或第三网络设备1203中以太虚拟私有网示例EVI在所述第二网络设备1202和/或第三网络设备1203申请的SRv6 SID；
第二网络设备1202和/或第三网络设备1203接收来自所述第一网络设备1201发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
第一网络设备1201接收来自第二网络设备1202和/或第三网络设备1203的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为以太虚拟私有网实例段标识EVI SID,所述EVI SID是以太虚拟私有网实例EVI在所述第二网络设备1202和/或第三网络设备1203申请的SRv6 SID；
第一网络设备1201根据所述EVI SID获得所述EVI SID和出接口的对应关系，所述出接口被所述第一网络设备1201用于向所述第二网络设备1202和/或第三网络设备1203发送目的地址为所述EVI SID的报文；
第一网络设备1201通过所述出接口向所述第二网络设备1202和/或第三网络设备1203发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
上述各种产品形态的网络设备，分别具有上述方法实施例中二层网关或三层网关的任意功能，此处不再赘述。
以上对本申请实施例进行了详细介绍，本申请实施例方法中的步骤可以根据实际需要进行顺序调度、合并或删减；本申请实施例装置中的模块可以根据实际需要进行划分、合并或删减。
应理解，说明书通篇中提到的“一个实施例”或“一实施例”意味着与实施例有关的特定特征、结构或特性包括在本申请的至少一个实施例中。因此，在整个说明书各处出现的“在一个实施例中”或“在一实施例中”未必一定指相同的实施例。此外，这些特定的特征、结构或特性可以任意适合的方式结合在一个或多个实施例中。应理解，在本申请的各种实施例中，上述各过程的序号的大小并不意味着执行顺序的先后，各过程的执行顺序应以其功能和内在逻辑确定，而不应对本申请实施例的实施过程构成任何限定。
本文中术语“和/或”，仅仅是一种描述关联对象的关联关系，表示可以存在三种关系，例如，A和/或B，可以表示：单独存在A，同时存在A和B，单独存在B这三种情况。另外，本文中字符“/”，一般表示前后关联对象是一种“或”的关系。
应理解，在本申请实施例中，“与A相应的B”表示B与A相关联，根据A可以确定B。 但还应理解，根据A确定B并不意味着仅仅根据A确定B，还可以根据A和/或其它信息确定B。
所属领域的技术人员可以清楚地了解到，为描述的方便和简洁，上述描述的系统，装置和单元的具体工作过程，可以参考前述方法实施例中的对应过程，在此不再赘述。
在本申请所提供的几个实施例中，应该理解到，所揭露的系统，装置和方法，可以通过其它的方式实现。例如，以上所描述的装置实施例仅仅是示意性的，例如，单元的划分，仅仅为一种逻辑功能划分，实际实现时可以有另外的划分方式，例如多个单元或组件可以结合或者可以集成到另一个系统，或一些特征可以忽略，或不执行。另一点，所显示或讨论的相互之间的耦合或直接耦合或通信连接可以是通过一些接口，装置或单元的间接耦合或通信连接，可以是电性，机械或其它的形式。
作为分离部件说明的单元可以是或者也可以不是物理上分开的，作为单元显示的部件可以是或者也可以不是物理单元，即可以位于一个地方，或者也可以分布到多个网络单元上。可以根据实际的需要选择其中的部分或者全部单元来实现本实施例方案的目的。
另外，在本申请各个实施例中的各功能单元可以集成在一个处理单元中，也可以是各个单元单独物理存在，也可以两个或两个以上单元集成在一个单元中。上述集成的单元既可以采用硬件的形式实现，也可以采用软件功能单元的形式实现。

Claims (41)

  1. 一种基于第6版互联网协议的段路由SRv6的通信方法，其特征在于，所述方法由二层网关执行，所述方法包括：
    生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
    向三层网关发布所述EVI-MAC路由。
  2. 根据权利要求1所述的方法，其特征在于，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
  3. 根据权利要求1或2所述的方法，其特征在于，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
  4. 根据权利要求2-3中任一项所述的方法，其特征在于，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
  5. 根据权利要求4所述的方法，其特征在于，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
  6. 根据权利要求1-5任一项所述的方法，其特征在于，所述方法还包括：
    所述二层网关向所述三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
    所述二层网关接收所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
  7. 根据权利要求1-6任一项所述的方法，其特征在于，所述EVI SID为end.dt2u类型的SID。
  8. 根据权利要求1-7任一项所述的方法，其特征在于，所述二层网关和所述三层网关部署于园区网络。
  9. 根据权利要求1-8任一项所述的方法，其特征在于，所述二层网关基于IPv6段路由尽力而为SRv6 BE进行报文转发。
  10. 一种基于第6版互联网协议的段路由SRv6的通信方法，其特征在于，所述方法由三层网关执行，所述方法包括：
    接收二层网关通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
    根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文。
  11. 根据权利要求10所述的方法，其特征在于，所述根据所述EVI SID,获得所述EVI SID和出接口的对应关系，包括：
    根据所述EVI SID查找路由表，获得所述对应关系，其中，所述路由表包括所述对应关系。
  12. 根据权利要求10或11所述的方法，其特征在于，所述EVI-MAC路由包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表，所述方法还包括：
    根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
  13. 根据权利要求12所述的方法，其特征在于，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
  14. 根据权利要求10-13任一项所述的方法，其特征在于，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
  15. 根据权利要求10-14任一项所述的方法，其特征在于，所述方法还包括：
    接收来自所述二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
    根据所述EVI SID和所述出接口的对应关系,确定通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
    通过所述出接口向所述二层网关发送所述ARP响应报文。
  16. 根据权利要求10-15任一项所述的方法，其特征在于，所述EVI SID为end.dt2u类型的SID。
  17. 根据权利要求10-16任一项所述的方法，其特征在于，所述二层网关和所述三层网关部署于园区网络。
  18. 根据权利要求10-17任一项所述的方法，其特征在于，所述三层网关为基于IPv6段路由尽力而为SRv6 BE进行报文转发的集中式网关。
  19. 一种网络设备，用作二层网关，其特征在于，包括：
    处理模块，用于生成基于以太虚拟私有网实例EVI的媒体接入控制EVI-MAC路由，其中，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
    收发模块，用于向三层网关发布所述EVI-MAC路由。
  20. 根据权利要求19所述的网络设备，其特征在于，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
  21. 根据权利要求19或20所述的网络设备，其特征在于，所述二层网关关闭向所述三层网关发布所述EVI中的主机MAC路由的功能。
  22. 根据权利要求20-21中任一项所述的网络设备，其特征在于，所述EVI-MAC路由还包括指示信息，所述指示信息指示所述三层网关避免将所述EVI-MAC路由下发到转发面的MAC转发表。
  23. 根据权利要求22所述的网络设备，其特征在于，所述EVI-MAC路由包括扩展团体 属性，所述扩展团体属性用于承载所述指示信息。
  24. 根据权利要求19-23任一项所述的网络设备，其特征在于，
    所述收发模块，还用于向所述三层网关发送地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
    所述收发模块，还用于接收所述三层网关发送的ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID。
  25. 根据权利要求19-24任一项所述的网络设备，其特征在于，所述EVI SID为end.dt2u类型的SID。
  26. 根据权利要求19-25任一项所述的网络设备，其特征在于，所述二层网关和所述三层网关部署于园区网络。
  27. 根据权利要求19-26任一项所述的网络设备，其特征在于，所述二层网关基于IPv6段路由尽力而为SRv6 BE进行报文转发。
  28. 一种网络设备，用作三层网关，其特征在于，包括：
    收发模块，用于接收二层网关通告的基于以太虚拟私有网实例的媒体接入控制EVI-MAC路由，所述EVI-MAC路由包括以太虚拟私有网实例段标识EVI SID,所述EVI SID是所述EVI在所述二层网关申请的SRv6 SID，所述EVI-MAC路由中携带的MAC地址不包括所述EVI中各主机的MAC地址；
    处理模块，用于根据所述EVI SID，获得所述EVI SID和出接口的对应关系，所述出接口被所述三层网关用于向所述二层网关发送目的地址为所述EVI SID的报文。
  29. 根据权利要求28所述的网络设备，其特征在于，
    所述处理模块，还用于根据所述EVI SID查找路由表，获得所述对应关系，其中，所述路由表包括所述对应关系。
  30. 根据权利要求28或29所述的网络设备，其特征在于，
    所述处理模块，还用于根据所述指示信息的指示，避免将所述EVI-MAC路由下发到转发面的MAC转发表。
  31. 根据权利要求30所述的网络设备，其特征在于，所述EVI-MAC路由包括扩展团体属性，所述扩展团体属性用于承载所述指示信息。
  32. 根据权利要求28-31任一项所述的网络设备，其特征在于，所述EVI-MAC路由中携带的所述MAC地址为所述二层网关的MAC地址，或者，为全F的MAC地址。
  33. 根据权利要求28-32任一项所述的网络设备，其特征在于，
    所述收发模块，还用于接收来自所述二层网关的地址解析协议ARP请求报文，所述ARP请求报文的源互联网协议SIP地址为所述EVI SID；
    所述处理模块，还用于根据所述EVI SID和所述出接口的对应关系,确定通过所述出接口向所述二层网关发送ARP响应报文，所述ARP响应报文的目的互联网协议DIP地址为所述EVI SID；
    所述收发模块，还用于通过所述出接口向所述二层网关发送所述ARP响应报文。
  34. 根据权利要求28-33任一项所述的网络设备，其特征在于，所述EVI SID为end.dt2u 类型的SID。
  35. 根据权利要求28-34任一项所述的网络设备，其特征在于，所述二层网关和所述三层网关部署于园区网络。
  36. 根据权利要求28-35任一项所述的网络设备，其特征在于，所述三层网关为基于IPv6段路由尽力而为SRv6 BE进行报文转发的集中式网关。
  37. 一种网络设备，用作二层网关，其特征在于，包括；
    存储器，存储有指令；
    处理器，用于执行所述指令，使得所述二层网关执行如权利要求1至9任一项所述的方法。
  38. 一种网络设备，用作三层网关，其特征在于，包括：
    存储器，存储有指令；
    处理器，用于执行指令，使得所述三层网关执行如权利要求10至18任一项所述的方法。
  39. 一种通信系统，其特征在于，所述通信系统包括二层网关和三层网关，所述二层网关为如权利要求37所述的网络设备，所述三层网关为如权利要求38所述的网络设备。
  40. 一种计算机可读存储介质，包括指令，其特征在于，当所述指令被处理器执行时，实现权利要求1-18任一项所述的方法。
  41. 一种计算机程序产品，包括程序，其特征在于，当所述程序被处理器执行时，实现权利要求1-18任一项所述的方法。
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