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Re: IPv6 not operational (was Re: Consensus Call: draft-weil-shared-transition-space-request)

2011-12-08 15:00:22
Not sure why rfc1981 PMTUD was never fixed. I've repeatedly tried to
suggest to just forget about PMTUD for IP multicast, and i have never
come across a good use case to justify MTU > 1280 for IP multicast
across the Internet.

We did manage to get section 11.1 into rfc 3542 though. It's a little
bit long due to committee design, but i was hoping it was sufficient to avoid
the problem by default. It recommends sender side MIN_MTU fragmentation
by default for IP multicast sent into IPv6 sockets.

If folks see IPv6 multicast > 1280 as a
real problem in deployments, pleae let me know. It would either indicate
socket stacks not observing rfc3542 or intentionally badly written
applications.

Cheers
    Toerless

Daryl Tanner wrote:

The IPv6 "chickens and eggs" discussion could (and probably will) go on
forever:

service provider ->  no content

IPv6 is the right answer,

Wrong.

IPv6 is not operational, which is partly why most service
providers refuse it.

For example, to purposelessly enable multicast PMTUD, RFC2463
(ICMPv6) mandates routers generate ICMPv6 packet too big
against multicast packets, which causes ICMPv6 packet
implosions, which is not operational.

For further details, see my presentation at the last APNIC:

      How Path MTU Discovery Doesn't work
      http://meetings.apnic.net/__data/assets/file/0018/38214/pathMTU.pdf

                                              Masataka Ohta
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