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Inter-AS VPN Notes

Inter-AS VPN

 – VNPv4 communication between 2 ASs to exchange client routes


 – Each client would require a separate L3 interface for the separate VRFs

     -> Subinterfaces are commonly used to solve this

Client-to-client over multiple ASs must be a Labeled Switched Path (LSP), unless a VRF is being used somewhere in an AS

Thee are three was to enable inter-AS communication

 – Inter-AS Option (10) A

     -> Back-to-back VRF

 – Inter-AS Option (10) B

     -> ASBR VPNv4 MP-eBGP

 – Inter-AS Option (10) C

     -> Multihop MP-BGP

Cisco Docs:

MPLS VPN Inter-AS IPv4 BGP Label Distribution

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