Configuring inter-AS option B
To configure inter-AS option B, perform configurations on PEs and ASBRs.
PE configuration:
Configure basic MPLS L3VPN, and specify the ASBR in the same AS as an MP-IBGP peer. The route targets for the VPN instances on the PEs in different ASs must match for the same VPN. For information about PE configuration, see "Configuring basic MPLS L3VPN."
ASBR configuration:
Configure a routing protocol, and enable MPLS and LDP on the interface connected to an internal router of the AS.
Specify the PE in the same AS as an MP-IBGP peer, and the ASBR in a different AS as an MP-EBGP peer.
Disable VPN target filtering for VPNv4 routes so the ASBR can maintain all VPNv4 routes and advertise the routes to the peer ASBR.
Enable MPLS capability on the interface connected to the ASBR in another AS. There is no need to configure a label distribution protocol, for example, LDP.
An ASBR always sets itself as the next hop of VPNv4 routes advertised to an MP-IBGP peer regardless of the peer next-hop-local command.
To configure inter-AS option B on an ASBR:
Step | Command | Remarks |
|---|---|---|
1. Enter system view. | system-view | N/A |
2. Enter interface view of the interface connected to an internal router of the AS. | interface interface-type interface-number | N/A |
3. Enable MPLS on the interface. | mpls enable | By default, MPLS is disabled on the interface. |
4. Enable MPLS LDP on the interface. | mpls ldp enable | By default, MPLS LDP is disabled on the interface. |
5. Return to system view. | quit | N/A |
6. Enter interface view of the interface connected to the remote ASBR. | interface interface-type interface-number | N/A |
7. Enable MPLS on the interface. | mpls enable | By default, MPLS is disabled on the interface. |
8. Return to system view. | quit | N/A |
9. Enter BGP instance view. | bgp as-number [ instance instance-name ] [ multi-session-thread ] | N/A |
10. Create a BGP peer. | peer { group-name | ipv4-address [ mask-length ] } as-number as-number | By default, no BGP peers exist. Configure PEs in the same AS as IBGP peers, and ASBRs in different ASs as EBGP peers. |
11. Enter BGP VPNv4 address family view. | address-family vpnv4 | N/A |
12. Enable BGP to exchange VPNv4 routes with the PE in the same AS and the ASBR in different ASs. | peer { group-name | ipv4-address [ mask-length ] } enable | By default, BGP cannot exchange VPNv4 routing information with a peer. |
13. Disable route target filtering of VPNv4 routes. | undo policy vpn-target | By default, route target filtering is enabled for received VPNv4 routes. Only VPNv4 routes whose export route target attribute matches local import route target attribute are added to the routing table. |