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Date:      Fri, 29 Jun 2001 07:58:16 -0400
From:      Clark Gaylord <cgaylord@vt.edu>
To:        freebsd-net@freebsd.org
Subject:   Re: fastforwarding?
Message-ID:  <20010629075815.N55750@e028121.vtacs.vt.edu>
In-Reply-To: <3B3AB4F8.184A2EFE@softweyr.com>; from wes@softweyr.com on Wed, Jun 27, 2001 at 10:39:20PM -0600
References:  <GPEOJKGHAMKFIOMAGMDICEOJDGAA.deepak@ai.net> <20010626093545.D49992@sunbay.com> <3B3AB4F8.184A2EFE@softweyr.com>

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On Wed, Jun 27, 2001 at 10:39:20PM -0600, Wes Peters wrote:
> Ruslan Ermilov wrote:
> > On Mon, Jun 25, 2001 at 06:47:41PM -0400, Deepak Jain wrote:
> > > ...
> > > What does the fastforwarding option do that the normal forwarding option
> > > doesn't?
> > >
> > See inet(4).
> 
> The description there isn't very forthcoming.  fastforwarding caches
> the results of a route lookup for destination addresses that are not
> on the local machine, and uses the cached route to short-circuit the
> normal (relatively slow) route lookup process.  The packet flows 
> directly from one layer2 input routine directly to the opposing 
> layer2 output routine without traversing the IP layer.

I notice the man page points out that this prevents the use of
ipfilter, etc.  The first packet(s?) do get forwarded by the usual
process (yes?), so does this imply that at least a "deny X" would
still work (as the first packet would get denied and hence the
cache does not get populated)?  What are the limitations to ipfw
and friends working right in conjunction with fastforwarding?

Clark

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