Eirc,
IMHO, many implementations do NOT support
early-session,
In theory multiple early dialogs must be
supported by UAC,
so we can use one early dialog for early-media and another
one for final media.
It looks like a forking or logical
forking.
But in real world, many device does not support forking or
it can only support forking in terms of
signaling,not forking to establish multiple media
sessions.
Regards,
-Rockson
From: sipping-bounces@xxxxxxxx [mailto:sipping-bounces@xxxxxxxx] On Behalf Of wang.libo@xxxxxxxxxx
Sent: Monday, April 06, 2009 11:05 AM
To: Paul Kyzivat (pkyzivat)
Cc: sipping-bounces@xxxxxxxx; eric.wangxr@xxxxxxxxx; sipping@xxxxxxxx; Brett Tate
Subject: early-session & p-early-media /////Re: PRACK: Does non-200 response cease re-transmission ofreliable 18x?
Hi,
We introduce early-session to our system as it can solve media clip.
There are two ways to avoid media clip, early-session and forking p-early-media.
To support them both need all equipments (except proxies) update,
the problems you mentioned exist in both methods.
Do you mean, forking early media is better than early-session?
Regards,
Eric
From the beginning I found the early-session technique "interesting".
The problem I have with it is believing that people will attempt to
implement it, and if they do, that they will implement it correctly.
Given the amount of trouble that people seem to have implementing the
full o/a mechanism correctly, who likely is it that they will get it
right when trying to simultaneously manage two independent o/a
negotiations, most likely with the o/a role swapped between them, and
all multiplexed over the same invite. Its possible, but I'd like to hear
about it being tested at sipit.
Thanks,
Paul
wang.libo@xxxxxxxxxx wrote:
>
> Hi,
>
> Brett Tate has listed some.
> Also:
> o. Services can be supplied with fewer messages.It helps lighten the
> servers stress.
> o. You can recognize the session for the tone easily.
> o. It's useful for services such as CF(call forward),in which case there
> may be several early diologs.
>
> Regards,
> Eric
>
>
>
>
> > > Do you find some advantage to it over simply using early media
> > > with a different to-tag?
> >
> > It allows the early media session and answered media session to be
> > negotiated prior to INVITE 2xx. The main benefit is to reduce
> > clipping upon INVITE 2xx if forking has occurred and all UAS
> > actually support early-session.
> >
> > More specifically, UAS may assume only answered media will be sent
> > to the port for answer; thus it could quickly start rendering
> > answered media prior to receiving INVITE 2xx. UAC can allocate
> > other ports for early media; or it can refuse or hold early media
> > without it subsequently delaying answered media (by requiring
> > another offer/answer exchange).
> >
> > Works good in theory if all user-agents support it. I have no idea
> > how well it works in the real world. :)
> >
> > _______________________________________________
> > Sipping mailing list https://www.ietf.org/mailman/listinfo/sipping
> > This list is for NEW development of the application of SIP
> > Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip
> > Use sip@xxxxxxxx for new developments of core SIP
>
> --------------------------------------------------------
> ZTE Information Security Notice: The information contained in this mail is solely property of the sender's organization. This mail communication is confidential. Recipients named above are obligated to maintain secrecy and are not permitted to disclose the contents of this communication to others.
> This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the originator of the message. Any views expressed in this message are those of the individual sender.
> This message has been scanned for viruses and Spam by ZTE Anti-Spam system.
>
>
> ------------------------------------------------------------------------
>
> _______________________________________________
> Sipping mailing list https://www.ietf.org/mailman/listinfo/sipping
> This list is for NEW development of the application of SIP
> Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip
> Use sip@xxxxxxxx for new developments of core SIP
-------------------------------------------------------- ZTE Information Security Notice: The information contained in this mail is solely property of the sender's organization. This mail communication is confidential. Recipients named above are obligated to maintain secrecy and are not permitted to disclose the contents of this communication to others. This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error please notify the originator of the message. Any views expressed in this message are those of the individual sender. This message has been scanned for viruses and Spam by ZTE Anti-Spam system.
_______________________________________________ Sipping mailing list https://www.ietf.org/mailman/listinfo/sipping This list is for NEW development of the application of SIP Use sip-implementors@xxxxxxxxxxxxxxx for questions on current sip Use sip@xxxxxxxx for new developments of core SIP
