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

[Brian E Carpenter <[e-mail]>]

On 08/02/2017 09:32, [e-mail] wrote:
> Joe,
> 
> Thanks!
> 
>> I appreciate that you want to not point at PLPMTUD because it's not
>> widely supported, but **for the same reason** this doc should not hold
>> up this solution without pointing out very clearly that it basically
>> isn't going to be work.
> 
> 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.

This is not the document in which to fight the battle of interfering firewalls.

    Brian