Description

This article provides information about the link behavior of an Option B Inter as the VPN.

Symptoms

Information about the link behavior of an Option B Inter as the VPN.

Solution

 

The provider edge (PE) routers, within an AS, use the multiprotocol internal BGP (MP-IBGP) to distribute labeled VPN-IPv4 routes to an AS boundary router (ASBR). The AS boundary router uses MP-EBGP to distribute the labeled VPN-IPv4 routes to its peer AS boundary router (ASBR) in the neighboring AS. The peer AS boundary router then uses multiprotocol internal BGP (MP-IBGP) to distribute labeled VPN-IPv4 routes to PE routers. 

      IBGP             EBGP                IBGP
PE---------ASBR-----------ASBR-----------PE
BGP uses one NLRI (inet-vpn unicast) to communicate between the PE routes. So, this creates one pseudowire to communicate with the other site. If any link goes down along the path, it will take all the links down.