Configuring Inter-AS VPN Option B

Configuring MP-IBGP Between PEs and ASBRs in the Same AS

By importing extended community attributes to BGP, MP-IBGP can advertise VPNv4 routes between the PE and the ASBR.

Configuring MP-EBGP Between ASBRs in Different ASs

After the MP-EBGP peer relationship is established between ASBRs, either ASBR can advertise the VPNv4 routes of its AS to the other ASBR.

Controlling the Receiving and Sending of VPN Routes Using Routing Policies

An ASBR can either save all VPNv4 routes or partial VPNv4 routes (by filtering VPN targets through a routing policy).

(Optional) Storing VPN Instance Information on the ASBR

An ASBR that also functions as a PE must store VPN instance information.

(Optional) Enabling Next-Hop-based Label Allocation on the ASBR

To save label resources on an ASBR, you can enable next-hop-based label allocation on the ASBR. Note that next-hop-based label allocation and one label per instance need to be used together on the ASBR.

Configuring the Routing Protocol Between a CE and a PE

The routing protocol between a PE and CE can be BGP, static route, or IGP. You can choose any of them as required in the configuration process.