Re: Question about <draft-ietf-6man-deprecate-atomfrag-generation-03>

[Bob Hinden <[e-mail]>]

Tore,

> On Oct 29, 2015, at 5:02 PM, Tore Anderson <[e-mail]> wrote:
> 
> * Bob Hinden <[e-mail]>
> 
>> You may be reading this out of context.  The start of this section
>> starts with:
>> 
>>   IPv6 requires that every link in the internet have an MTU of 1280
>>   octets or greater.
>> 
>> RFC443 ICMPv6 that defines the ICMP Packet too Big message references
>> RFC1981 Path MTU Discovery (also referenced in this section) says:
>> 
>>   A node MUST NOT reduce its estimate of the Path MTU below the IPv6
>>   minimum link MTU.
>> 
>> I think this makes it clear what to do if an ICMP Packet Too Big
>> message is received with an MTU less than 1280.
> 
> Quite. Thank you for this clarification.
> 
> Then I can say that your proposed changes to -01 draft works for me.

Good thanks!

> 
>> However, this then goes on to say:
>> 
>>      Note: A node may receive a Packet Too Big message reporting a
>>      next-hop MTU that is less than the IPv6 minimum link MTU.  In
>> that case, the node is not required to reduce the size of subsequent
>>      packets sent on the path to less than the IPv6 minimun link MTU,
>>      but rather must include a Fragment header in those packets
>> [IPv6- SPEC].
>> 
>> That would also need to be updated (that is, remove this note), or
>> file an errata once the rfc2460bis is done.  The latter would be
>> easier.
> 
> Agreed. I had missed this fact that RFC1981 mandates the generation of
> atomic fragments. That should probably have been pointed out in
> draft-ietf-6man-deprecate-atomfrag-generation.

It’s quoting rfc2460, but I agree it needs to be fixed.

Thanks,
Bob

> 
> Tore