What is a requirement to share VRF reachability information to all members of a VPN when using IPv6?

Question

Options

• APE and CE routers must be running BGP as the PE-CE routing protocol
• BPE routers must have MPLS disabled and be running MP-BGP between all P and PE routers.
• CPE routers must be running MP-BGP and bgp default ipv4-unicast must be disabled
• DAll PEs must have the same VRFs configured.

• A
  16% (8)
• B
  4% (2)
• C
  8% (4)
• D
  73% (37)

Explanation

In MPLS L3VPN (including IPv6/6VPE), a PE router can only participate in a VPN if the corresponding VRF exists locally - without it, the router has no context in which to install or advertise VPN routes, making VRF presence on every member PE the foundational requirement for end-to-end reachability sharing.

Why the distractors fail:

• A is wrong because PE-CE routing is protocol-agnostic; OSPF, EIGRP, static routes, or BGP all work as PE-CE options.
• B is doubly wrong: MPLS must be enabled (not disabled) for label-switched forwarding, and P (core) routers do not participate in BGP in a standard MPLS VPN design.
• C is a plausible trap - MP-BGP with a VPNv6 address family is used in 6VPE, but disabling bgp default ipv4-unicast is a configuration preference, not a hard requirement for VRF reachability sharing.

Memory tip: Think of a VRF as a "membership card" for the VPN club - a PE router that doesn't hold the card can't participate, no matter what protocols are running. If even one member PE lacks the VRF, reachability breaks for that site.

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