Path MTU in node-requirements [was Re: FW: Evaluation of: draft-ietf-ipv6-node-requirements-07.txt ]

[Thomas Narten <narten@us.ibm.com>]

Jari Arkko <jari.arkko@kolumbus.fi> writes:

> john.loughney@nokia.com wrote:

> >>I'm astonished that Path MTU is a MAY -- I had thought it was 
> >>a MUST.  I'd really like some more text explaining what some 
> >>of the many exceptions are that are alluded to here.

> It follows RFC 2460, which states:

>     It is strongly recommended that IPv6 nodes implement Path MTU
>     Discovery [RFC-1981], in order to discover and take advantage of path
>     MTUs greater than 1280 octets.  However, a minimal IPv6
>     implementation (e.g., in a boot ROM) may simply restrict itself to
>     sending packets no larger than 1280 octets, and omit implementation
>     of Path MTU Discovery.


Seems to me, given the above wording, 2460 says Path MTU is a SHOULD,
not a MAY. Note that the MAY is about _not_ implementing it (in some
situations), not a "MAY" implement it in some subset of the comment
cases.

I.e, if node-requirements says MAY, I think that is a downgrade from
the SHOULD in 2460 as quoted above. I don't think this document should
be doing that.

Thomas

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