Hi Uri,
Attempting to answer below -
Multicast session - "Whether the UA should know the SDP with which
the session was set-up to INVITE itself to the session?" Perhaps not.
I think the UA needs to know the session identifers (From/To/Call-ID/Cseq)
and the multicast group address. If this information is available,
it can do a INVITE without SDP to the group and get the session
parameters from the peers. (Others can correct me if I am wrong here).
Unicast session - If you meant to ask, whether it is possible for a
UA To INVITE itself using SIP signalling... sure, its possible.
This is discussed in the RFC bis-09. Relevant lines quoted below:
(lines 3993-3998)
"When a tag is generated by a UA for insertion into a request or
response, it MUST be globally unique and cryptographically random
with at least 32 bits of randomness. A property of this selection
requirement is that a UA will place a different tag into the From
header of an INVITE as it would place into the To header of the
response to the same INVITE. This is needed in order for a UA to
invite itself to a session, a common case for "hairpinning" of calls
in PSTN gateways. Similarly, two INVITEs for different calls will
have different From tags, and two responses for different calls will
have different To tags."
Since we have different tags in the From and To headers (which are
unique), we have a unique identifier for a call even if we call
ourselves.
Hope that helps.
Regards,
Siddharth.
------------------
Siddharth Toshniwal @ Hughes Software Systems.
Bangalore, India.
http://www.hssworld.com
> -----Original Message-----
> From: Baniel Uri-CUB001 [mailto:[EMAIL PROTECTED]]
> Sent: Friday, June 28, 2002 7:42 AM
> To: [EMAIL PROTECTED]
> Subject: [Sip-implementors] Self invitation
>
>
> Say a UA wants to invite itself to a multicast session, would
> he need to
> have a prior knowledge about the media (mcast addressing,
> encoders etc) and
> then just send it to itself in the SDP element? Can a UA
> invite itself to a
> Unicast session (e.g. for testing purpose)?
>
> ==============================================================
> =========
> Uri Baniel - Distinguished Member of Technical Staff - Motorola
> Tel: (847) 632 4616; Fax: (847) 632 3963;
> "Learning that does not daily increase will daily decrease. - EWC
> ==============================================================
> =========
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