SR-MPLS Inter AS


Service providers frequently interconnect multiple autonomous systems and require seamless L3VPN service continuity across AS boundaries. We verified SR-MPLS interworking across two ASs following RFC 4364 Inter-AS Option C. We established end-to-end MP-BGP VPN reachability between two PEs, while the ASBRs in between were used to provide labeled transport across the AS boundary by means of BGP Labeled Unicast (BGP-LU). As the table below shows, we executed multiple role combinations, rotating PE and ASBR roles to test the end-to-end service. The L3VPN service exchange remained on the PE-to-PE MP-BGP control plane, while the ASBRs provided labeled transport across the AS boundary. To validate data plane forwarding, we connected traffic generators to both PEs and generated bidirectional PE-to-PE traffic across the inter-AS SR-MPLS network. Traffic forwarded successfully end-to-end in both directions with zero packet loss, confirming correct VPN reachability and correct inter-AS labeled transport using BGP-LU under the Option C model. Each AS operated its own IGP domain running IS-IS as the SR-MPLS control plane.

Figure 65

Figure 65: SR-MPLS Inter AS

CombinationPE1ASBR1ASBR2PE2
1Ericsson RAN Connect 6682Ribbon NPT-2507Raisecom RAX721-T-4C24Raisecom iTN8800-A
2Ribbon NPT-2507ZTE ZXCTN 6120H-ERaisecom RAX721-T-4C25ZTE ZXR10 M6000-2S16
3Ribbon NPT-2507Ericsson RAN Connect 6682Raisecom RAX721-T-4C26Raisecom iTN8800-A

Table 35: Combinations

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