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

[Donald Lee]

old good questions in sip, also add another "transaction".


On Fri, Apr 25, 2008 at 8:18 AM, 孙宗君 <szj087 at gmail.com> wrote:

> 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
> >
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-- 
BR
Donald
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