Subject: RE: [Tsvwg] sctp error check

From: [email-masked]
Date: Mon, 25 Jun 2001 19:09:16 +0300

> Imagine supporting the choice of two checksums, with different
> computational cost. The middlebox will always prefer to advertise and
> rewrite packets to use the less computationally-expensive checksum, in
> order to boost its performance.

	Well, actually the case we are discussing wouldn't allow this...
Being part of the VT makes that a change would make the receiver to drop the
packet... If you are saying that the routers would discard first the most
computationally-expensive packets, then it is another issue...

	BR Iván Arias Rodríguez

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From: Randall Stewart <[email-masked]>
Date: Mon, 25 Jun 2001 11:27:26 -0500

> computationally-expensive packets, then it is another issue...

If the middle box can re-write anything it wants.. why can it
not rewrite this bit in the tag area.. remember you are in
effect changing the meaning of the V-Tag. It is a 31 bit value
with your proposal (that I MUCH object to). And besides, the
middle box would also change the Initial-tag as well... remember
it would tweak with anything it wants!

R

-- 
Randall R. Stewart
[email-masked] 815-342-5222 (cell phone)

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From: Lloyd Wood <[email-masked]>
Date: Mon, 25 Jun 2001 17:38:26 +0100 (BST)

> computationally-expensive packets, then it is another issue...

Using a bit taken from the VT field != being part of the VT.

You want to overload a bit of the verification tag and provide an
explicit association between verification tag no (high bit - range;
low bit: even/odd) and checksum type? And completely rewrite the way
the verification tag must be assigned as a result?

L.

<[email-masked]>PGP<http://www.ee.surrey.ac.uk/Personal/L.Wood/>