[SIPForum-discussion] [Sip] What's the difference between session and dialog in SIP?

[孙宗君]

Hi, Vijay

Thanks very much for your timely answers.

>From this specification,  session is a combination of signaling plane
and media plane messages and processes that enable two or more
participants to communicate. I think session is a larger scope than
dialog. In another word, one session can contain more than one dialog.
Is what I understand right?

Zongjun


2008/4/24, Vijay K. Gurbani <vkg at alcatel-lucent.com>:
> There is some work progressing in the BMWG WG to create performance
>  metrics around SIP.  One of the first tasks in such an endeavor
>  is to define the notion of dialogs and sessions.  Please see
>  Section 3.1.1 of
> https://svn.resiprocate.org/rep/ietf-drafts/gurbani/bmwg-sip-bench-term/draft-ietf-bmwg-sip-term-00.txt
>  of the above draft for some insight.
>
>  Ëï×Ú¾ý wrote:
>
> > Hi, Lincoln
> >
> > thanks for your instructions.
> >
> > I know that dialog can exist without session since SUBSCRIBE/REFER can
> > create dialog and without any media between communication peers.
> >
> > What I want to know is the relationship of dialog and session when
> > they both exist in one communication activity. Take a example, when
> > there are 2 person participating talks with voice, we say there is a
> > dialog and a session.
> >
> > But when one caller invites another callee and gets five 200 final
> > responses from 5 UA every of which has its own session description. We
> > can say that there are 5 dialogs between caller and the other 5
> > callees, right? And then what is the exact number of session in this
> > scenario? One session or five session? That is what I want to know.
> >
> > Dialog is determined by dialogID (call-id, from/to tag) and session id
> > is determined by session id given in the SDP message.  My answer is
> > there are 5 dialog and one session now, right?
> >
>
>  - vijay
>  --
>  Vijay K. Gurbani, Bell Laboratories, Alcatel-Lucent
>  2701 Lucent Lane, Rm. 9F-546, Lisle, Illinois 60532 (USA)
>  Email: vkg@{alcatel-lucent.com,bell-labs.com,acm.org}
>  WWW:   http://www.alcatel-lucent.com/bell-labs
>