Re: draft-ietf-v6ops-mech-v2-00.txt

[Erik Nordmark <Erik.Nordmark@sun.com>]

> > If it is not implemented instead the node MUST instead
> > limit the size of the IPv6 packets it tunnels to 1280
> > bytes i.e., treat the tunnel interface as having a
> > fixed interface MTU of 1280 bytes.
> 
> "MUST NOT" send packet >1280
>    -> "MTU>1280" is "Absolute prohibition"
> 
> > An implementation MAY have a configuration knob which
> > can be used to set a larger value of the tunnel MTU
> > than 1280 bytes,
> 
> "MAY" -> "MTU>1280" is freely allowed
> 
> This seems to be quite in contradiction ?

Perhaps poor phrasing.
The intent is something along the lines of:

If the encapsulator does not implement dynamic tunnel MTU
it will use a fixed MTU for the tunnel.
The fixed MTU MUST default to 1280. It MAY be configurable but in that
case the default MUST be 1280.

Is that more clear?

  Erik