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Re: Last Call: <draft-ietf-6man-rfc1981bis-04.txt> (Path MTU Discovery for IP version 6) to Internet Standard

2017-02-08 15:52:13
On 08/02/2017 18:05, Randy Bush wrote:
Would something like this help?
(borrowed from https://en.wikipedia.org/wiki/Path_MTU_Discovery)

"Many network security devices block all ICMP messages for perceived
 security benefits, including the errors that are necessary for the proper
 operation of PMTUD. This can result in connections that complete the
 TCP three-way handshake correctly, but then hang when data is transferred.
 This state is referred to as a black hole connection."

Yes. What we are asked to do for Internet Standard is show that a protocol
is widely deployed and is interoperable. That's undoubtedly true of RFC1981.
The fact that it also has an important failure mode should certainly be
documented, but I suspect that every Internet Standard has at least
one important failure mode.

the problem is that this particular failure mode is essentially "does
not work on the real internet."  perhaps documenting that is useful.
but i guess this is ipv6.

I fully agree that it should be documented, but the details are already
documented elsewhere. In this document it can be quite short.

It isn't just because it's IPv6, although I haven't noticed any recent
attempts to promote RFC 1191 to Internet Standard. There is RFC 1435 of
course, which says that RFC 1191 doesn't work. That went unanswered for
14 years, until RFC 4821.

   Brian

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