[e2e] purpose of pseudo header in TCP checksum

Alok alokdube at hotpop.com
Tue Feb 15 08:45:29 PST 2005

not really, it was a design decision given the constraints :)
good and bad are for time to decide...........
----- Original Message ----- 
From: "Michael Welzl" <michael.welzl at uibk.ac.at>
To: "Noel Chiappa" <jnc at mercury.lcs.mit.edu>
Cc: <alokdube at hotpop.com>; <end2end-interest at postel.org>
Sent: Tuesday, February 15, 2005 9:35 PM
Subject: Re: [e2e] purpose of pseudo header in TCP checksum

> > In IPv4, the IP header checksum does cover the SA/DA - it covers
> > everything in the IP header, including the hop count. In IPv6, there is
> > no header checksum, of course.
> ...which was a bad decision IMO, because it breaks the
> "IP over everything" model and will now lead to problems
> with mechanisms such as UDP Lite, where link layers are
> now required check the headers (but ONLY the headers)
> of things above. Yuck.
> Cheers,
> Michael

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