Subject: [SIP] distributed sip

From: "farhan" <[email-masked]>
Date: Fri, 29 Sep 2000 00:03:42 +0530

is there anything that prevents a sip deployment such that all the ua's
behind a sip proxy are not sip compliant ?
let me build this up slowly.
1. consider a multi-user host that can run individual sip UAs for each user
logged in.
2. we can replace the multiple instances of UA with a single user agent that
is able to handle more than one simultaneous user. This may not seem
efficient, but there is nothing which prevents such a deployment.
3. now consider that the physical endpoints are in turn remotely located.

We will at this stage have a distributed SIP wherein, the actual endpoints
of a sip call are slave units of a central control unit and the control unit
in turn is sip compliant (the slave units are not).

I am placing this architecture for review because of my interest in getting
sip into smaller stacks. With an approach wherein, we locate the sip stack
on a central host and attach the communication end points as slaves of
host, we retain all the goods of sip while at the same time we will be able
to afford far simpler and leaner clients. All we need to ensure is that the
end points are in themselves capable of handling RTP.

our hotfoon.com deployment is on similar lines. i can well imagine this as a
route to interoperability with other protocols too.
we can consider the communication endpoints to be some sort of "remote
device drivers" of the sip stack that communicate with sip stack using some
very simple protocol (just two calls: setup and clear down). Our hotfoon
client is just a 48kb slave totally controlled by hotfoon.com. As a result.,
we never upgrade our client, we only upgrade the server at hotfoon.com.

i am considering using this approach on our hotfoon deployment. will there
be any issues of interoperability?

- farhan

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From: "Gary Cote" <[email-masked]>
Date: Fri, 29 Sep 2000 11:06:43 -0500

So you're basically running a proprietary call control protocol
between the SIP server and your endpoints? You're not asking about
the relative merits of such architecture (you clearly have your reasons),
you're simply enquiring out interoperability? Is that right?

I can imagine such a setup for a SIP-enabled wireless network, or
possibly for java-based clients: an architecture optimized for thin
clients and control protocols.

Anyway, in terms of pure protocol interoperability, I would imagine 
your solution will be interoperable to the degree that your SIP 
server is SIP-compliant. That's pretty straightforward.

Feature interoperability, however, will depend on how feature-rich
your proprietary protocol is. For example, what if somebody tries to
initiate a multicast session, change media encoding schemes mid-call, 
or perform some other mid-call signaling? These are all perfectly
legitimate operations for a SIP session. Will you be able to perform
the logical equivalents through your proprietary control protocol? 

My two cents,

 - Gary

> -----Original Message-----
> From: [email-masked]
> [mailto:[email-masked]]On Behalf Of farhan
> Sent: Thursday, September 28, 2000 1:34 PM
> To: sip
> Subject: [SIP] distributed sip
> 
>