Abstract: This application provides a packet sending method, a network device, and a system. The method includes: A first network device receives an advertisement message sent by a second network device, where the advertisement message includes segment routing policy SR policy information and traffic feature information, and the SR policy information includes a segment identifier list SID list. The first network device establishes a correspondence between the traffic feature information and the SID list according to the advertisement message, where the correspondence is used to guide forwarding of a packet including the traffic feature information.

Abstract: In a route processing method, a first network device obtains one or more routes having a same destination address, and including a first route. Slice information corresponding to the one or more ports is determined based on one or more ports that are on the first network device and that receive the one or more routes. The first network device sends an updated first route to a second network device, where the updated first route carries the slice information and the destination address. After a route is received, corresponding slice information is determined based on a port that receives the route, so that slice information supported by a path from a network device to a route starting device is determined. The determined slice information is carried when the route is forwarded, so that a network device on a route advertisement path can obtain the slice information supported by the entire path.

Abstract: A link information sending method, a communication apparatus, and a system, and can be applied to the field of communications technologies. The method may include: a first node determines first link information, where the first link information indicates a link from the first node to a second node. The first node receives a first packet from the second node, where the first packet includes second link information and first indication information, the second link information indicates a link from the second node to the first node, and the first indication information indicates that the second link information is to-be-checked link information. Then, the first node may check the first link information and the second link information based on the first indication information.

Abstract: This application provides a route processing method and a network device that are applied to the Internet. Specifically, the method includes: A first network device determines that a first BGP route is unavailable, and then the first network device determines a second BGP route associated with the first BGP route, where the first BGP route and the second BGP route are from a same autonomous system AS. In other words, a path through which the first BGP route is transmitted and a path through which the second BGP route is transmitted include the same AS. Then, the first network device reduces a priority of the second BGP route.

Abstract: Embodiments of this application disclose a route information processing method and an apparatus, which may be used for a network device that supports a BGP protocol, to resolve a defect in an existing BGP SPF protocol. The network device may be a forwarding device, for example, a router or a switch. For example, in embodiments of this application, a priority attribute is introduced to route information that carries NLRI through an extended BGP protocol, to indicate a priority of the route information. This influences a BGP NLRI selection process performed by the network device. For example, embodiments of this application provide a network fault processing method, to help resolve a problem that a network device cannot calculate a packet forwarding path in some scenarios in an existing protocol.

Abstract: This application discloses a communication method and a related apparatus, and relates to the field of communication technologies. The method is applied to an SD-WAN overlay network. A CPE autonomously generates an SD-WAN overlay routing table, so that communication reliability and flexibility are improved. An RR specifies an overlay multicast RPF route to the CPE to implement SD-WAN overlay multicast communication, and the CPE does not need to perform path computation autonomously, so that a computing power requirement of the CPE is reduced. An identifier of the CPE and an identifier of a site are carried in a multicast join message to implement the SD-WAN overlay multicast communication. A standard IP header is carried in a multicast service packet to implement the SD-WAN overlay multicast communication, so that generalization, applicability, and compatibility are improved.

Abstract: In a route processing method, a first network device obtains one or more routes having a same destination address, and including a first route. Slice information corresponding to the one or more ports is determined based on one or more ports that are on the first network device and that receive the one or more routes. The first network device sends an updated first route to a second network device, where the updated first route carries the slice information and the destination address. After a route is received, corresponding slice information is determined based on a port that receives the route, so that slice information supported by a path from a network device to a route starting device is determined. The determined slice information is carried when the route is forwarded, so that a network device on a route advertisement path can obtain the slice information supported by the entire path.

Abstract: A multicast communication method is applied to a software-defined wide area network SD-WAN. In the multicast communication method, a bit index explicit replication (Bit Index Explicit Replication, BIER) capability is deployed on site devices in the SD-WAN, a BIER header in a multicast packet indicates a site device that a multicast packet needs to pass through, and no multicast distribution tree need to be constructed. In addition, the multicast packet is forwarded through an SD-WAN tunnel between site devices, and an intermediate node does not need to sense a multicast service, to reduce a quantity of multicast table entries on a network device and accelerate convergence of the multicast table entries, so that normal running of the multicast service is ensured.

Abstract: A multicast communication method is applied to a software-defined wide area network SD-WAN. In the multicast communication method, a bit index explicit replication (Bit Index Explicit Replication, BIER) capability is deployed on a site device in the SD-WAN, a site device through which a multicast packet needs to pass is indicated by a bit index explicit replication IPv6 encapsulation (Bit Index Explicit Replication IPv6 encapsulation, BIERv6) header in the multicast packet, and a multicast distribution tree does not need to be constructed. In addition, the multicast packet is forwarded through an SD-WAN tunnel between site devices, and an intermediate node does not need to sense a multicast service. In this way, a network device has a small quantity of multicast entries and the multicast entries are converged quickly, ensuring normal running of the multicast service.