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Date: Thu, 6 May 2004 12:22:28 -0700 (PDT)
From: Julian Elischer <julian@elischer.org>
To: Andre Oppermann <andre@freebsd.org>
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Subject: Re: Default behaviour of IP Options processing
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On Thu, 6 May 2004, Andre Oppermann wrote:

> I have just committed the attached change to ip_input() to control the
> behaviour of IP Options processing.  The default is the unchanged
> current behaviour.
[...]
> routing.  The remaining IP Options are RR (record route) and TS (time
> stamp) which are both useless.  For finding out which path a packet takes
> we use traceroute instead of RR.  Besides that RR is limited to the space
> in the IP Options field and can possibly record only a few hops (9 IIRC).
> Time stamp is useless for the same reason and since it doesn't have a
> fixed and synchronized timebase it is even more so useless.
> 
> Opinions?  Discussion?  Yes/Nay?

I use RR all the time.
it allows you to record the reverse path, (up to the size limitation).

what about inet6 ? do you plan on doing things there? 
There are more options defined there..