Subject: [SIP] on routing logic at proxy

From: "rafi" <[email-masked]>
Date: Fri, 7 Jul 2000 17:37:10 +0530

Hi,

     What all things  proxy takes into consideration
when it forks a request. I am interested in knowing
routing logic. As Rosenberg says  "routing logic may 
have changed (perhaps there was some time of day routing 
or randomized routing)." in one of his reply.  What makes
proxy to decide upon selecting particular routing logic for e.g.
randomized routing logic.  Does routing logic depends on the
Method. If yes how exactly.

Regards
Rafi Assadi H.M.
Silicon Automation Systems
Bangalore, INDIA

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From: "Jo Hornsby" <[email-masked]>
Date: Fri, 7 Jul 2000 13:36:17 +0100

> when it forks a request.

Absolutely anything it likes -- the temperature in Wales, for
instance.  And as a result, it might not even fork; it might
return "500 Proxy Too Cold".

> I am interested in knowing

Routing decisions are where the real power of SIP lies.  I
guess there's some sort of notion of a "vanilla proxy", which
does trivial resolution from the SIP URL in the Request-URI to
0 or more other SIP URLs, perhaps purely as the result of a
database lookup, but this is by no means the end of the story.

So when it comes down to it, routing logic is way outsida the
SIP RFC.  Look to some of the drafts available, such as CPL and
Caller Preferences, for ideas on typical (routing) services.

HTH,

 - Jo.

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From: "rafi" <[email-masked]>
Date: Fri, 7 Jul 2000 18:27:10 +0530

> return "500 Proxy Too Cold".

    If routing at proxy is all that independent of
the transcation it is carring on then I  think  it may
end up in  generating unncessary message into
the network. For e.g take the case srinath is
talking about. Can  proxy act so dump in this  such cases ?

Thanks
Rafi Assadi H.M.

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From: Jonathan Rosenberg <[email-masked]>
Date: Fri, 07 Jul 2000 11:05:39 -0400

> talking about. Can  proxy act so dump in this  such cases ?

If the proxy is routing "dumbly", I suggest you buy someone elses.

Routing is the core function of a proxy. As Jo has said, it can be done
in many
ways besides the simple request URI based mechanisms formally specified.
How it
is done, and in what ways it can be controlled, is at the core of
building proxy applications.

-Jonathan R.

-- 
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
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