Usage Scenario
After creating a VPN instance and enabling the IPv4 address family for the VPN instance, you must run the route-distinguisher command to configure an RD for the address family.
Different VPN instances may have the same route prefix. To allow a PE to determine to which VPN instance a route belongs, run the route-distinguisher command to configure an RD for the VPN instance IPv4 address family on the PE. After the configuration, the PE will add an RD to the route received from the VPN instance, and then the route prefix becomes a globally unique VPN IPv4 route.
Precautions
After an RD in the IPv4 address family for a VPN instance is deleted using the undo route-distinguisher command, configurations in the IPv4 address family as well as the IPv4 address family-related configurations in the BGP view will be deleted. Therefore, exercise caution when you run this command.