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Re: Path MTU Hop-by-Hop Option

Carsten Bormann <cabo@tzi.org> Wed, 17 October 2018 04:50 UTC

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Subject: Re: Path MTU Hop-by-Hop Option
From: Carsten Bormann <cabo@tzi.org>
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Date: Wed, 17 Oct 2018 06:49:50 +0200
Cc: IPv6 List <ipv6@ietf.org>, Gorry Fairhurst <gorry@erg.abdn.ac.uk>
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To: Bob Hinden <bob.hinden@gmail.com>
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On Oct 17, 2018, at 00:55, Bob Hinden <bob.hinden@gmail.com> wrote:
> 
> This document specifies a new Hop-by-Hop IPv6 option that is used to
>   record the minimum Path MTU

A while ago I proposed something similar to collect information about adaptation layer fragmentation MTUs (information about which is truly not available in any other way):

https://tools.ietf.org/html/draft-bormann-intarea-alfi-04

(I also only looked at the Internet layer here — leaving it as an exercise to put in transport/application protocol support.)

After mulling an initial version of the proposal, there was pretty much consensus that hop-by-hop options were not really available on the Internet.  So I put in an alternative way to collect the information, see above if you are interested.  Then at some point SPUD came along and I was hoping that would lead to a framework within in which this information could be better handled.

Maybe it’s time to pull the old draft out again.  The hop-by-hop option problem of course hasn’t gone away.

Grüße, Carsten

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