Inter-AS VPN Option-B Overview
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Inter-AS Option B is a more scalable solution compared to Option A. It does not require any VRFs on the ASBRs, it uses VPNv4 eBGP to exchange VPNv4 updates. |
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Single interface to connect the ASBRs. |
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Packets are sent labelled between the ASBRs. |
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No need for VRFs on the ASBR. |
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ASBRs must be directly connected. |
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Scales better than Option A. |
ASBR BGP label allocation mode uses per-prefix label allocation, and per- label allocation cannot be achieved in ASBRs (VPNv4 and VPNv6).
Topology
Figure 31. InterAS-VPN Option-B
Virtual Routing and Forwarding label allocation cannot be achieved in ASBRs (VPNv4 and VPNv6).