What is Inter AS Option A?

Inter AS Option A: an ASBR router in one Autonomous System attaches directly to an ASBR router in another Autonomous System. The two ASBR routers are attached to multiple sub-interfaces; at least one of the VPNs whose routes need to be passed from one AS to the other AS is attached.

What is InterAS Option B?

The InterAS option B (with RFC 3107) implementation ensures complete IGP isolation between the data centers and WAN. When BGP advertises a particular route to ASBR, it also distributes the label which is mapped to that route.

What is MPLS BGP forwarding?

mpls bgp forwarding command is automatically configured when setting VPNv4 eBGP session, it specifies that interfaces connected to the peer could forward labels over it and received labelled frames. Usually any interfaces not running mpls (i.e. LDP/RSVP) will drop all labels and try to forwarding using IP.

Which is the best option for Interas option a?

InterAS option A – In an interAS option A network, autonomous system border router (ASBR) peers are connected by multiple subinterfaces with at least one interface VPN that spans the two ASes. These ASBRs associate each subinterface with a VPN routing and forwarding (VRF) instance and a BGP session to signal unlabeled IP prefixes.

How does Inter-as option a network work?

In an Inter-AS Option A network, ASBR peers are connected by multiple subinterfaces with at least one interface VPN that spans the two autonomous systems. These ASBRs associate each subinterface with a VPN routing and forwarding (VRF) instance and a Border Gateway Protocol (BGP ) session to signal unlabeled IP prefixes.

Where can I find Inter-as Option C?

This method is described in RFC 4364—BGP/MPLS IP Virtual Private Networks (VPNs) (February 2006). Inter-AS option C, similarly to the carrier-of-carriers configuration, requires a label-switched path from a packet’s ingress PE router to its egress PE router.

How to configure MPLS Inter-as option AB?

Enable Cisco Express Forwarding, which is required for the MPLS VPN routing and forwarding operation. Identify the VPNs for the MPLS VPN–Inter-AS Option AB network and configure the VRFs to which these VPNs belong. These VRFs are used for Inter-AS Option AB connections on the ASBR interface.