Configuring Longest Match of Multicast Route

If the longest match principle is configured for route selection, a multicast device prefers the route with the longest matched mask. If the mask lengths of multiple routes are the same, the device selects a route as the multicast data forwarding path in the order of the static multicast route, inter-domain unicast route, and intra-domain unicast route.

Prerequisites

Before configuring longest match of multicast route function, complete the following tasks:

Configuring a unicast routing protocol
Configuring basic multicast functions

Context

Configurations related to VPN instances are applicable only to the Provider Edge (PE) device. When configuring the longest match of multicast routes for a VPN instance on a PE, perform the configuration in the VPN instance. In other cases, the longest match is configured in the public network instance.

By default, routes are selected in the order of routing entries.

Procedure

Public network instance
1. Access the system view.
  system-view
2. Select routes according to the longest match.
  multicast longest-match
VPN instance
1. Access the system view.
  system-view
2. Access the VPN instance view.
  ip vpn-instance vpn-instance-name
3. Enable the IPv4 address family for the VPN instance and access the VPN instance IPv4 address family view.
  ipv4-family
4. Select routes according to the longest match.
  multicast longest-match