From: Craig Milo Rogers <rogers@ISI.EDU>
To: michael@linuxmagic.com
Cc: linux-kernel@vger.kernel.org
Subject: Re: [UPDATE] zerocopy.. While working on ip.h stuff
Date: Mon, 26 Feb 2001 18:31:59 -0800 [thread overview]
Message-ID: <18431.983241119@ISI.EDU> (raw)
In-Reply-To: Your message of "Mon, 26 Feb 2001 17:53:30 PST." <0102261753300I.02007@mistress>
>> a competing philosophy that said that the IP checksum must be
>> recomputed incrementally at routers to catch hardware problems in the
...
>ah.. we do recalculate IP Checksums now.. when we update any of the
>timestamp rr options etc..
But, do you do it incrementally? By which I mean: subtract
(appropriately) the old value of the octet from the existing checksum,
field in the packet then add (appropriately) the new value of the
octet to the checksum? Simply recalculating the IP checksum from
scratch can generate a "correct" checksum for a packet that was
damaged*** while waiting around in memory.
I don't know if people worry about this now, but 20 years ago
there was a fuss about it. Further discussion offline, please.
Craig Milo Rogers
*** Maybe by hardware trouble, or maybe because someone followed a bad
pointer and stomped on part of the header.
next prev parent reply other threads:[~2001-02-27 2:32 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <2137.983232656@ISI.EDU>
2001-02-27 1:53 ` [UPDATE] zerocopy.. While working on ip.h stuff Michael Peddemors
2001-02-27 2:31 ` Craig Milo Rogers [this message]
2001-02-23 6:59 [UPDATE] zerocopy BETA 3 David S. Miller
2001-02-25 3:38 ` Chris Wedgwood
2001-02-25 3:54 ` Jan Rekorajski
2001-02-26 23:46 ` [UPDATE] zerocopy.. While working on ip.h stuff Michael Peddemors
2001-02-26 23:23 ` Andi Kleen
2001-02-26 23:25 ` David S. Miller
2001-02-26 23:47 ` Benjamin C.R. LaHaise
2001-02-27 0:05 ` David S. Miller
2001-02-27 0:11 ` Benjamin C.R. LaHaise
2001-02-27 3:41 ` Michael Peddemors
2001-02-27 3:24 ` Michael Peddemors
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=18431.983241119@ISI.EDU \
--to=rogers@isi.edu \
--cc=linux-kernel@vger.kernel.org \
--cc=michael@linuxmagic.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox