Subject: [PCN] pcn-3-in-1-encoding & IPv4 header checksum recalculation

From: Bob Briscoe <[email-masked]>
Date: Mon, 20 Jul 2009 11:07:13 +0100

Toby,

In

pcn-3-in-1-encoding we should add a parenthesis reminding the
implementer:

"

(The IPv4 header checksum changes when the ECN field changes.)

"

RFC3168 said how to update the checksum when ECT(0) -> CE

For ECT(1) -> CE it just said "it can be done
similarly"

In 3-in-1 we also have ECT(0) - > ECT(1) and ECT(1) to CE
transitions.

I don't think we need to say how the checksum should be updated in each
case - an implementer can work this out. We just need to remind them to
do it.

Bob

________________________________________________________________

Bob
Briscoe,
Networks Research Centre, BT Research