Question on "identification" field of IP header
Ramesh Shankar <RShankar@novell.com> Fri, 13 December 2002 14:49 UTC
Message-ID: <3DF9F380.1070403@Novell.com>
Date: Fri, 13 Dec 2002 07:49:36 -0700
From: Ramesh Shankar <RShankar@novell.com>
Organization: Novell Inc.
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To: end2end <end2end-interest@postel.org>, TCP-IMPL <tcp-impl@grc.nasa.gov>
Subject: Question on "identification" field of IP header
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If the "Don't fragment bit" is set in the IP header, what purpose does the "identification" field serve? Why can't I simply put 0 for this field in such a case? I remember coming across some e-mail chain in one of the mailing lists (TCP-IMPL, e2e, TSVWG) about this issue and the interaction with NAT. But I am not sure what came out of that discussion. Also, some of the "OS fingerprinting" techniques in the networking world apparently use the IP ID field to identify various operating systems. Apparently some operating systems (or protocol stacks, if you prefer) don't increment this by 1. Why would anyone want to do this? Wouldn't this cause possibles issues wrt to wrap around in the possible case of fragmentation? One could always argue that with high speed Ethernet, that anyway would be a possibility, but I would like to understand the reason behind such a case. Thanks for your time, S.R.
- Question on "identification" field of IP header Ramesh Shankar
- Re: Question on "identification" field of IP head… der Mouse
- Re: Question on "identification" field of IP head… Alan Cox
- Re: Question on "identification" field of IP head… David Borman
- Re: Question on "identification" field of IP head… Ramesh Shankar
- Re: Question on "identification" field of IP head… der Mouse
- Re: [e2e] Re: Question on "identification" field … Ramesh Shankar