Source address of ICMP messages in 6PE

Bernhard Schmidt berni at
Sun Dec 18 23:37:28 CET 2005

Hi everyone,

can someone tell me the rules for source address selection of ICMPv6
error messages when they are sourced on the egress PE in a 6PE
environment? Are there any rules for it? Is it the same across the major
vendors/versions? I couldn't find anything in
draft-ooms-v6ops-bgp-tunnel-05 or the cisco docs.

As far as I understood you are not required to configure an IPv6 address
on every MPLS-enabled interface facing your core, so that rules out that
source. There was a command in Cisco called "mpls ipv6
source-interface", but the docs don't make clear whether that is only
used for locally initiated connections (e.g. ping/trace from the CLI) or
not. It has also been removed from IOS in 12.2(25)S.

My observations with GBLX (the only larger 6PE network I use every day)
are that it seems to use the own address on the egress interface to the
original destination. Unfortunately I don't have enough MPLS-capable lab
boxes at the moment and I don't want to rip my native IPv6, so can
anyone shed light on this darkness? :-)


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