Subject: [SIP] I-D ACTION:draft-ietf-sip-state-00.txt

From: [email-masked]
Date: Tue, 07 Nov 2000 06:05:14 -0500

A New Internet-Draft is available from the on-line Internet-Drafts directories.
This draft is a work item of the Session Initiation Protocol Working Group of the IETF.

	Title		: SIP Extensions for supporting Distributed Call State
	Author(s)	: B. Marshall et al.
	Filename	: draft-ietf-sip-state-00.txt
	Pages		: 12
	Date		: 06-Nov-00
	
This document describes an extension to the Session Initiation
Protocol (SIP) that enables proxies to distribute call state to user
agents. The state information can be returned to the proxy when the
user agent requests a change in the characteristics of the active
call. By providing the ability to distribute state to the user
agents where it can be securely stored, proxy servers can remain
stateless for the duration of the call. This mechanism allows a
proxy server to provide services that depend on call state, while
still being stateless.

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---

From: "Anuraj Kunnummel Ennai" <[email-masked]>
Date: Thu, 09 Nov 2000 12:21:55 +0530

Hi ,
Went through the distributable call state draft. It is a move in the
right
direction as the proxies should be holding as little state information
as
possible in order to scale up.

But it seems the idea of having a separate state header might not be
needed. The nesting of  state headers across proxies adds to
complexity and overhead. Existing UA implementations cannot
support state header.

An alternative will be to use the Record-route option already defined.
The proxy which adds a  record route header(means the proxy is
interested
in keeping track of the call.)can add the state info duly encrypted as a

parameter to record route header.

Now only the proxy which inserted the record route header needs to
interpret
the state parameters. Note that record route is valid per call leg
basis. Thus the
proxy can selectively choose call legs which it is interested in. .The
UA
implementations need not worry as they are supposed to insert the
Record-route
header unchanged into the responses.

As record - routing support is mandatory, this seems to be a better
solution that
needs very little changes. Also alleviates the need to live with one
more header!!!

This is what I feel from the first look...Or am I missing something?

Thanks & regards
Anuraj Ennai
SIP Designer
Wipro Technologies -Bangalore-India

Subject:
        [SIP] I-D ACTION:draft-ietf-sip-state-00.txt
   Date:
        Tue, 07 Nov 2000 06:05:14 -0500
   From:
        [email-masked]
     To:
        IETF-Announce: ;
    CC:
        [email-masked]

A New Internet-Draft is available from the on-line Internet-Drafts
directories.
This draft is a work item of the Session Initiation Protocol Working
Group of the IETF.

        Title           : SIP Extensions for supporting Distributed Call
State
        Author(s)       : B. Marshall et al.
        Filename        : draft-ietf-sip-state-00.txt
        Pages           : 12
        Date            : 06-Nov-00

Internet-Drafts are also available by anonymous FTP. Login with the
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---

From: William Marshall <[email-masked]>
Date: Thu, 9 Nov 2000 17:23:14 -0500 (EST)

Use of an added parameter on Record-Route was considered early
as a way to do the equivalent to State headers (like about 3-4
IETF meetings ago) and was rejected.

From our collective memory, there were several problems with 
overloading Route.

Record-Route headers actually FORCE the subsequent messages to
go to the proxy mentioned.  We wanted something that was disjoint
from routing, that would be usable if the message arrived there,
but didn't force all the future messages to be routed thee.

We also wanted the ability to insert multiple State headers in
a message, and to attach State headers to requests for transfers
(like when Refer-To is referring to an existing call that is to
be replaced).

There was also a good deal of confusion with using Route, that the
Route header for a proxy was removed before the request was sent
to it.  Therefore the state information had to be off by 
one entry in the Record-Route list, and that it was different
in the forward and reverse directions.

Bill Marshall (on behalf of all the DCS team who contributed to this response)
[email-masked]

-----original message-----
From: "Anuraj Kunnummel Ennai" <[email-masked]>
To: [email-masked]
Subject: Re:[SIP] I-D ACTION:draft-ietf-sip-state-00.txt
Date: Thu, 09 Nov 2000 12:21:55 +0530

Hi ,
Went through the distributable call state draft. It is a move in the right
direction as the proxies should be holding as little state information as
possible in order to scale up.

An alternative will be to use the Record-route option already defined.
The proxy which adds a  record route header(means the proxy is interested
in keeping track of the call.)can add the state info duly encrypted as a
parameter to record route header.

Now only the proxy which inserted the record route header needs to interpret
the state parameters. Note that record route is valid per call leg basis. Thus the
proxy can selectively choose call legs which it is interested in. .The UA
implementations need not worry as they are supposed to insert the Record-route
header unchanged into the responses.

As record - routing support is mandatory, this seems to be a better solution that
needs very little changes. Also alleviates the need to live with one more header!!!

Thanks & regards
Anuraj Ennai
SIP Designer