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Re: transmech MTU comments
On Thu, 20 Nov 2003, Fred Templin wrote:
> Your message was a cop-out, Pekka. Please address the question:
Ok..
> Do we, or do we not want to allow for the possibility of
> future L2 bridges, switches, hubs etc. that connect media
> with dissimilar MTUs but that don't get involved with
> L3 functions like IPv4 fragmentation and sending
> "packet too big" ICMPs?
No, I don't believe this is an immediate goal.
> So, why can't we set the MTU of our 802.11 interfaces to
> 2312 and take immediate advantage of the 35% gain in
> efficiency? Because there might be an 802.11/Ethernet
> L2 bridge somewhere on the path and IPv4 path MTU
> discovery would break!
>
> The current IPv4 path MTU discovery scheme is limiting
> potential growth and precluding legitimate solution alternatives.
> While we can't fix it all in one fell swoop, we can start making
> informed decisions (e.g., non-assumption of IPv4 fragmentation,
> support for packetization-layer path MTU discovery that does
> not require ICMPs, etc.) that will eventually bring about healing
> and new growth opportunities.
I agree that this may be an interesting direction to explore, but
there does not yet seem to be a general agreement about whether the
IETF will be moving to this direction or not. (Not sure if people
even agree about a problem statement?)
When such mechanisms have not been even fully? specified(?) for IPv4,
it would seem to be premature to do it for IPv6-over-IPv4, especially
considering the stage where we're at now.
(I don't have full knowledge of the situation where this stands at the
moment, but this is my impression..)
This seems to be close to a pre-engineering/research question at the
moment; not something I think is suitable for inserting into a
specification moving towards Draft Standard.
--
Pekka Savola "You each name yourselves king, yet the
Netcore Oy kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings