[35353] in North American Network Operators' Group
Re: Loose Source Routing
daemon@ATHENA.MIT.EDU (John Hawkinson)
Wed Mar 7 12:30:09 2001
Date: Wed, 7 Mar 2001 12:22:10 -0500
From: John Hawkinson <jhawk@bbnplanet.com>
To: Vadim Antonov <avg@kotovnik.com>
Cc: nanog@merit.edu
Message-ID: <20010307122210.S23712@jhawk-foo.bbnplanet.com>
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In-Reply-To: <Pine.LNX.4.04.10103061902510.11495-100000@kitty.kotovnik.com>; from avg@kotovnik.com on Tue, Mar 06, 2001 at 07:24:34PM -0800
Errors-To: owner-nanog-outgoing@merit.edu
> Now, LSRR is _expensive_. Modern routers handle packets with options in
> hardware, and doing IP options in hardware is not cheap.
Conveniently, not very many of them are sent.
> (BTW, what other options are actually used? :) IMO, prohibiting IP
> options altogether would be a good idea (and don't ask me about
> fragmentation).
I use the timestamp option sometimes.
And the record route (no source routing) option.
I do suspect that I'm one of a very small set with respect to the
former, however.
> As for debugging routing - isn't it much better to ask OFRVs to add
> remotely accessible traceroute servers to their boxes? There is no
> engineering or economic justification for diagnostic fucntionality like
> LSRR to stay anywhere close to the fast packet path.
While this might be nice in theory, I think that it would be a political
nightmare to deploy. Thus leaving us with the status quo.
It also has nasty state implications.
--jhawk
