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Re: draft-wbeebee-ipv6-cpe-router-04 comments
On 20 jul 2009, at 18:23, Mikael Abrahamsson wrote:
Why do you guess this?
Because the people who mess up usually have larger packet sizes than
But why 1350 and not 1349 or 1351?
because the brokenness comes from tunnels.
Brokenness comes from people filtering ICMP but still having PMTUD
much more likely to get it right than the guys who try to run 1500
and get it wrong.
You confuse "works" with "right". That's exactly how the problem you
try to solve started. While I can imagine operators displaying this
level of pragmatism, we have to do better in the IETF.
So the question is, do we try to work around the brokenness or do we
just do the right thing ourselves and call everybody else "broken"
and sit there with a less working IPv6 than we could have.
Going along with people who break the specifications is a road that
leads nowehere fast.
The problem with setting an arbitrary packet size is not just that
it's a race to the bottom (of course now someone runs a tunnel over a
link with a 1350 MTU so you need to use a 1330 MTU etc etc) but also
that there is no exit strategy. Even if you upgrade everything to use
a link layer that supports bigger packets, you're still sending 1350-
Now at least that last problem is solvable by not hardcoding "1350"
but "link layer MTU - IPv4 (+IPsec+...) header".
So I think the question is, is this document about doing it right or
getting it to work to the largest extent as possible?
See the E in IETF.