Re: RFC 1812, section 4.2.2.5
Tony Li <tli@cisco.com> Fri, 15 September 1995 03:44 UTC
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From: Tony Li <tli@cisco.com>
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To: fred@cisco.com
Cc: craig@aland.bbn.com, rreq@isi.edu
In-Reply-To: <v02130500ac7e9ade669a@[171.69.128.114]> (fred@cisco.com)
Subject: Re: RFC 1812, section 4.2.2.5
> 1. You must verify the IP checksum even if you use incremental checksum > updating. > It seems to me that it says - when you verify the checksum, you must add up all five words and verify that the result is a negetive zero - when you bump the TTL, you need not recalculate the entire checksum; you may bump the existing (checked) checksum by the negative of the amount you change the TTL. which is to say, interpretation 1. My recollection was that there was major debate here, with my current employer among those whose implementations were of version 2 ("the end system is going to check it, and routing has developed a spanning tree, so why should the router check it?") and that interpretation lost. Does anyone have other recollections or opinions? I agree with your interpretation. However, I would like to make it quite clear that your current employer has NEVER, EVER used or supported interpretation 2. I'll also point out that interpretation 1 is inconsistent with the design of IPv6. Tony
- RFC 1812, section 4.2.2.5 Craig Partridge
- Re: RFC 1812, section 4.2.2.5 Fred Baker
- Re: RFC 1812, section 4.2.2.5 Tony Li
- Re: RFC 1812, section 4.2.2.5 Fred Baker
- Re: RFC 1812, section 4.2.2.5 Frank Kastenholz
- Re: RFC 1812, section 4.2.2.5 Frank Kastenholz
- Re: RFC 1812, section 4.2.2.5 John Shriver
- Re: RFC 1812, section 4.2.2.5 Tony Li
- Re: RFC 1812, section 4.2.2.5 Noel Chiappa
- Re: RFC 1812, section 4.2.2.5 William Chops Westfield
- Re: RFC 1812, section 4.2.2.5 Tony Li
- Re: RFC 1812, section 4.2.2.5 braden