Currently a service provider provides IPv4 traceroute services between MPLS PE routers. The provider wants to implement IPv6 with MPLS 6PE/6VPE and then provide parallel IPv6 traceroute services betwe

P routers in a 6PE/6VPE network only perform MPLS label switching based on the top label and never inspect the IPv6 payload, so ICMPv6 support is unnecessary and would not contribute to IPv6 traceroute functionality.

PE routers must support ICMPv6 so they can generate ICMPv6 Time Exceeded messages in response to traceroute probes that arrive with an expired Hop Limit. Without ICMPv6, the PE cannot send the reply that identifies it as a hop in the traced path. This is the IPv6 equivalent of the ICMPv4 TTL-exceeded response used in traditional traceroute.

A core benefit of 6PE/6VPE is that P routers require no IPv6 support, keeping the provider core upgrade-free; all IPv6 processing is handled exclusively at the PE boundaries.

PE routers must support full IPv6 to maintain IPv6 routing tables, forward IPv6 packets, and encapsulate IPv6 traffic into MPLS label stacks for transport across the provider core. Full IPv6 support at the PE is the foundational requirement of 6PE/6VPE, as the PE is the boundary where IPv6 and MPLS meet.