When RIP is used as the PE-CE protocol for VPRNs (IP-VPNs), the RIP metric is only used by the local node running RIP with the Customer Equipment (CE). The metric is not used to or encoded into and MP-BGP path attributes exchanged between PE routers.
The RIP metric can also be used to be exchanged between PE routers so if a customer network is dual homed to separate PEs the RIP metric learned from the CE router can be used to choose the best route to the destination subnet. By using the learned RIP metric to set the BGP MED attribute, remote PEs can choose the lowest MED and in turn the PE with the lowest advertised RIP metric as the preferred egress point for the VPRN. Figure: RIP metric propagation in VPRNs shows RIP metric propagation in VPRNs.
