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Re: Question on Source Routing Option
From: Valdis.Kletnieks () vt edu
Date: Tue, 25 Sep 2001 12:12:39 -0400

On Tue, 25 Sep 2001 15:56:56 -0000, tarun banka <t_banka () hotmail com>  said:

server to client and vice versa.   I am aware that source routing option is 
disabled because of security risks. I want to know is there any tool which 
can help  me in finding what routers that can support source routing. It 

The problem you will find is that even if you can locate a router that
supports source routing, the chances are high that there will be one or more
routers that actively block source-routed packets.

Depending on what you're trying to research, you *may* be able to get by
with a setup as follows:

                  B
                /   \
               A      D
                 \  /
                   C

and using pairs of VPN tunnels (A-B B-D) and (A-C C-D) to simulate source
routing.

Not only is source routing often a security issue, it also suffers from
major workability problems: a) it doesn't scale well (tragedy of the commons)
even if you find a better path, if everybody does it, the better path isnt
better anymore.  b) If you're source routing through someplace that becomes
unreachable, the routing protocols know, but you dont.

Much historical info on why source routing doesn't work can be found in
old UUCP bang-paths - seismo!<something>!sandbox!clutx! was mine for a while,
and of course mail didnt move if something-sandbox wasnt working....


-- 
                                Valdis Kletnieks
                                Operating Systems Analyst
                                Virginia Tech

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