L2VPNs and BGP/MPLS VPNs
BGP multiprotocol extensions (MP-BGP) enable BGP to support IPv4 services such as BGP/MPLS VPNs, which are sometimes known as RFC 2547bis VPNs. An L2VPN is actually a BGP-MPLS application that has much in common with BGP/MPLS VPNs.
The procedures for configuring BGP signaling for BGP/MPLS VPNs and for L2VPNs are similar except that for L2VPNs you must configure both of the following address families:
- L2VPN—The L2VPN address family enables you to configure the PE router (L2VPNs) or VE router (VPLS) to exchange layer 2 NLRI for all L2VPN or VPLS instances. Optionally, you can use the signaling keyword with the address-family command for the L2VPN address family to specify BGP signaling of L2VPN reachability information. Currently, you can omit the signaling keyword with no adverse effects.
- VPWS—The VPWS address family enables you to configure the PE router to exchange layer 2 NLRI for a specified VPWS (L2VPN) instance.
BGP can exchange information in an L2VPN topology within these address families.