Re: Genart telechat review of draft-ietf-6man-rfc1981bis-06

Bob Hinden <bob.hinden@gmail.com> Fri, 05 May 2017 12:32 UTC

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From: Bob Hinden <bob.hinden@gmail.com>
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Subject: Re: Genart telechat review of draft-ietf-6man-rfc1981bis-06
Date: Fri, 05 May 2017 15:32:12 +0300
In-Reply-To: <497d3868-406a-a38f-56d8-391b0fc16032@isi.edu>
Cc: Bob Hinden <bob.hinden@gmail.com>, Stewart Bryant <stewart.bryant@gmail.com>, gen-art@ietf.org, IPv6 List <ipv6@ietf.org>, IETF <ietf@ietf.org>, draft-ietf-6man-rfc1981bis.all@ietf.org
To: Joe Touch <touch@isi.edu>
References: <149305392811.25808.15115824976388262628@ietfa.amsl.com> <497d3868-406a-a38f-56d8-391b0fc16032@isi.edu>
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> On Apr 25, 2017, at 9:26 PM, Joe Touch <touch@isi.edu> wrote:
> 
> Hi, Stewart,
> 
> 
> On 4/24/2017 10:12 AM, Stewart Bryant wrote:
>> Minor issues:
>> 
>> A node MUST NOT reduce its estimate of the Path MTU below the IPv6
>> minimum link MTU.
>> 
>> SB> I missed this last time.
>> SB>
>> SB> Presumably you mean "A node MUST NOT reduce its estimate of the
>> SB> Path MTU below the IPv6 minimum link MTU in response to such
>> SB> a message."
> This seems fine to me, FWIW - i.e., limiting the advice in this doc to
> the mechanism in  this doc.

I will add something, but this sentence follows:

   If a node receives a Packet Too Big message reporting a next-hop
   MTU that is less than the IPv6 minimum link MTU, it MUST discard it.

so I think the context was clear.

Bob


> 
>> SB>
>> SB> Otherwise I would have thought that this was entirely a matter
>> SB> for the host whether it wanted to use a Path MTU below the IPv6
>> SB> link minimum. Nothing breaks if the host takes a more conservative
>> SB> decision.
> I don't agree; the host at that point is violating RFC2460. It should
> never think that an IPv6 link or path with an MTU below what RFC2460
> requires is valid.
> 
> Joe
>