An international retailer needs to enable IPv6 communication between the remote spokes' sites and the hub site in a short period of time, but the MPLS WAN provider does not support IPv6. What…

Question

Options

• AIPv6 over DMVPN
• BIPv6 over GRE
• CNAT64
• DLISP

• A
  80% (28)
• B
  3% (1)
• C
  11% (4)
• D
  6% (2)

Explanation

A is correct: DMVPN (Dynamic Multipoint VPN) uses mGRE (multipoint GRE) tunnels combined with NHRP (Next Hop Resolution Protocol) to create a dynamic, scalable hub-and-spoke (and spoke-to-spoke) overlay network. Crucially, IPv6 traffic can be tunneled inside IPv4 GRE encapsulation across an IPv4-only MPLS WAN. The retailer's IPv6 packets are encapsulated in IPv4 headers at the spoke sites, transported across the IPv4 MPLS network, and decapsulated at the destination. DMVPN is the preferred solution over plain GRE because it supports dynamic spoke-to-spoke tunnels (especially Phase 3), scales to many spokes without requiring manual static tunnel configuration between every site pair, and supports IPv6 as a passenger protocol over IPv4 transport. B (plain GRE) requires static point-to-point tunnels between every site pair, which is not scalable for a large retailer. C (NAT64) translates between IPv6 and IPv4 addressing - it does not enable end-to-end IPv6 communication. D (LISP) is more complex and designed for mobility/multi-homing use cases, not the primary recommended solution for IPv6-over-IPv4-MPLS transport in a retail WAN context.

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