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Date: Tue, 29 Apr 2008 10:14:59 -0700
From: Julian Elischer <julian@elischer.org>
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To: "Wilkinson, Alex" <alex.wilkinson@dsto.defence.gov.au>, 
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Subject: Re: Multiple routing tables in action...
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Wilkinson, Alex wrote:
>     0n Sat, Apr 26, 2008 at 08:44:30AM -0700, Julian Elischer wrote: 
> 
>     >A little progress report
>     >From a recently installed (6.3) machine.... (plus patches)
> 
> Ok, being ignorant to this, possibly a silly question:
> 
>   Why would i want or need multiple routing tables ?

any time you wnat to base a route upon something other than just
the destination address.  It's basically called "Policy based
routing".


Trivial examples:
You have two ISPs and you want to send all SMTP via one link and
all other traffic via the other.

You have 3 ISPs and want all traffic from the accounting department
to go via a particular path (that is encrypted) but regular office
chatter to go via another.

I have other more complex examples in my work.

I'm sure others have more solid examples as well.

google for policy routing.