Configuring inter-AS option A

Inter-AS option A applies to scenarios with a few VPNs.

To configure inter-AS option A, create VPN instances on PEs and ASBRs. The VPN instances on PEs are used to allow CEs to access the network, The VPN instances on ASBRs are used to access the peer ASBRs. An ASBR considers the peer ASBR as a CE.

The route targets configured on the PEs must match those configured on the ASBRs in the same AS to make sure VPN routes sent by the PEs (or ASBRs) can be received by the ASBRs (or PEs). Route targets configured on the PEs in different ASs do not have such requirements.

For more information, see "Configuring basic MPLS L3VPN."