Subject: [SIP] The Option-tag of supported:

From: "Bodgey" <[email-masked]>
Date: Sat, 7 Oct 2000 18:22:08 +0530

Hi,
I have some questions of Option-tag. Now there are many extesions of SIP, a
sip entity must use "Supported" header to indicate what extension the it
support so that it can communicate with other entitys with the same
function. Is there some option-tags to indicate extensions of all the
extension such as PRACK, INFO, MIME for ISUP etc?
On other hand, the SIP-T contain many extensions such as PRACK, INFO.
Perhaps, we can use one Option-tag to indicate it, isn't it?
Would someone give a answer? Thanks!

Bodgey

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From: [email-masked]
Date: Sat, 7 Oct 2000 13:02:45 -0600

The process of encapsulating ISUP in and of itself does not currently
require any kind of option-tag. It is generally desirable in SIP-T that an
endpoint should process ISUP if possible (if it's a gateway), but ignore it
if not. The Content-Disposition header can therefore specify whether or not
the handling of any particular MIME body is required for the session to
continue. So, essentially, the Content-Disposition header can be used to
communicate whether or not ISUP needs to be used. Supplying additional MIME
bodies is a function of the multipart/mixed MIME type, not an extension to
SIP.
 
INFO and, if necessary, PRACK for SIP-T can be marked as Required/Supported.
I don't really have any feelings one way or another about grouping multiple
option-tags under umbrella tags, except in so far as it seems like there
will be more symbols that an endpoint will have to be able to recognize,
even if there are less tags transmitted in any particular signal.
 
Jon Peterson
Level(3) Communications

-----Original Message-----
From: Bodgey [mailto:[email-masked]]
Sent: Saturday, October 07, 2000 6:52 AM
To: [email-masked]
Subject: [SIP] The Option-tag of supported:

Hi, 
 
Bodgey

_______________________________________________
SIP mailing list
[email-masked]
http://lists.bell-labs.com/mailman/listinfo/sip

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From: Jonathan Rosenberg <[email-masked]>
Date: Tue, 10 Oct 2000 02:51:32 -0400

There are several ways that SIp is extended, and there are different ways to
indicate/negotiate that depending on which one is used.

For new methods (i.e, INFO) the 405/Allow mechanism is used.

For new content in the bodies, the 415/Accept mechanism is used.

For extensions that include new headers/semantics, the 420/Require mechanism
(which usage option tags), is used.

Each draft that is a real extension defines a new option tag. When these
become RFCs, those tags are registered with IANA.

As Jon points out, SIP-T is not a real extension; it uses a new method and
some new bodies, and is thus covered by the 405/Allow and 415/Accept
mechanisms.

-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

> From: [email-masked] [mailto:[email-masked]]
> Sent: Saturday, October 07, 2000 3:03 PM
> To: [email-masked]
> Cc: [email-masked]
> Subject: RE: [SIP] The Option-tag of supported:
> 
>