MPLS Configuration on Cisco IOS Software

Outbound Route Filters

When implementing large-scale MPLS VPN networks, sites belonging to different customers might not be connected to all the PE routers in the MPLS VPN domain. The PE router in the MPLS VPN network can, therefore, conserve resources by importing only VPNv4 routes that are to be imported into VRF instances configured on the PE router. To enable such filtering of VPNv4 route information, the PE router must be capable of filtering MP-iBGP updates so that information pertaining to these superfluous routes is not received. The procedure for filtering routes based on the VRF configuration on the PE routers is called automatic route filtering. Automatic route filtering is enabled by default on all Cisco routers that are configured ...