Something with filters

Eric Vyncke (evyncke) evyncke at
Thu Aug 28 16:28:53 CEST 2014

The mapped IPv4 address is probably coming out of a 6PE (or 6VPE) MPLS router where the HopLimit field is copied into the MPLS header and when the poor P router in charge of sending the ICMPv6 has no IPv6 address at all… This is per RFC and perhaps an explanation why uRPF is not activated?

No explanation about the :: address though…

As a security person, I would love to have uRPF enabled where possible but I am afraid that even in IPv4 it is not deployed everywhere :-(


PS: indeed, ask your vendors for features, customers have much more power than you guess :-)

From: Lorenzo Colitti <lorenzo at<mailto:lorenzo at>>
Date: jeudi 28 août 2014 07:46
To: Jeroen Massar <jeroen at<mailto:jeroen at>>
Cc: IPv6 Ops list <ipv6-ops at<mailto:ipv6-ops at>>
Subject: Re: Something with filters

On Wed, Aug 27, 2014 at 9:01 AM, Jeroen Massar <jeroen at<mailto:jeroen at>> wrote:
 9  2001:5a0:a00::2e (2001:5a0:a00::2e)  79.018 ms  79.910 ms  79.960 ms
10  :: (::)  101.893 ms  102.004 ms  103.574 ms
11<> (::ffff:  104.732 ms

Yeah baby, we can use the unspecified address in ICMP replies!

The mapped IPv4 address in there is pretty cool, too...
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