From: Vlad Yasevich <redacted>
Date: Mon, 28 Jul 2008 14:09:55 -0400

The IPv6 checks are much different.  The MUST requirement is to provide as much
data as possible upto IPv6 min mtu.  So, the IPv6 icmp code should probably look
to see if min(payload_len, min_mtu) is provided.

"Be liberal in what you accept..." -Jon Postel

Also, do you know any case where 576 bytes won't provide enough
quoted packet bytes? :-)