What happens when Option AB is configured in an Inter-AS MPLS VPN?

The correct answer is B. Two directly connected PE-ASBRs exchange VPNv4 prefixes and labels using MP-EBGP. Inter-AS Option AB combines the back-to-back VRF static routes of Option A with an MP-EBGP VPNv4 peering of Option B between the two ASBRs. This means each VRF on the ASBRs peers over EBGP and exchanges VPNv4 NLRI along with the associated MPLS labels directly.

Layer 3 VPNs

Question

Options

AA single MP-BGP session is established between ASBRs and exchanges VPNv4, IPv4, and
BTwo directly connected PE-ASBRs exchange VPNv4 prefixes and labels using MP-EBGP.
CThe route reflectors exchange customer VPNv4 prefixes over multihop MP-EBGP and VPNv4
DA single PE-CE EBGP session per VRF is established between ASBRs in which each ASBR

How the community answered

(27 responses)

A
4% (1)
B
93% (25)
D
4% (1)

Explanation

Inter-AS Option AB combines the back-to-back VRF static routes of Option A with an MP-EBGP VPNv4 peering of Option B between the two ASBRs. This means each VRF on the ASBRs peers over EBGP and exchanges VPNv4 NLRI along with the associated MPLS labels directly.

Topics

#Inter-AS MPLS VPN#Option AB#MP-EBGP#VPNv4 label exchange

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