Subject: RE: [SIP] Redirect VS Proxy Server

From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 14 Nov 2000 10:46:57 -0500

I believe the difference is fundmentally one of control.

You use a proxy when you want to control processing of the call from the
point you receive it, and forward. A proxy can see the provisional and final
responses to the request. It can record route so that it sees whats going on
during the call. A redirect server, however, hands off control to the device
that sent it the INVITE. It will never see the final response to the
request, and not be contacted again for the remainder of the call. Its a
one-shot deal.

As such, redirect servers are really good for high volume, lookup style
transactions. They can almost be considered a form of database query, albeit
a SIP specific one. Proxies are generally needed for services and more
complex routing problems.

-Jonathan R.

---
Jonathan D. Rosenberg                       72 Eagle Rock Ave.
Chief Scientist                             First Floor
dynamicsoft                                 East Hanover, NJ 07936
[email-masked]                     FAX:   (973) 952-5050
http://www.cs.columbia.edu/~jdrosen         PHONE: (973) 952-5000
http://www.dynamicsoft.com

> -----Original Message-----
> From: Billy Biggs [mailto:[email-masked]]
> Sent: Monday, November 13, 2000 8:38 PM
> To: Schmidlin, David
> Cc: [email-masked]
> Subject: Re: [SIP] Redirect VS Proxy Server
> 
> 
> Schmidlin, David ([email-masked]):
> 
> > Why/Where would you use a redirect server over a proxy 
> server and vice
> > versa?
> 
>   If you were a web server, when would you send a redirect and when
> would you proxy?  It's the same answer.
> 
>   Redirect servers are cheap to code, for one.  But these are logical
> roles not separate entities, so your question should be more specific.
> 
>   In general you proxy a message when you are providing some 
> additional
> feature rather than simply performing a lookup.
> 
> -- 
> Billy Biggs, 3Com               Email: [email-masked]
> http://www.div8.net/billy/      Phone: [email-masked]
> 
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