Hi Salil
Please rules of Offer answer.
The rules for sending offers:
- offer may be sent in INVITE
- if there was no offer in INVITE, offer MUST be sent in first reliable
response to INVITE
- offer may be sent in 100rel (reliable 1XX series response)
- offer may be sent in PRACK
- offer may be sent in UPDATE
PRACK may only be sent when an unacknowledged 100rel (reliable 1XX series
response) is received. UPDATE may be sent during early or established
dialog.
Only one INVITE request may be pending within a dialog. Only one non-INVITE
request may be pending within a dialog (in one direction): it is not
possible to send UPDATE if no final response has been received to PRACK.
If there is already an offer/answer exchange in progress, no offer MUST be
sent. Offer/answer exchange is in progress if offer has been sent but no
answer has been received, or if an offer has been received but no answer has
been generated.
The rules for sending answer:
- when offer is received with INVITE
- answer MAY be sent with next end-to-end 1XX or 2XX response
- answer MUST be sent in a reliable response (100rel or 2XX)
- when offer is received in 2XX response
- answer MUST be sent in ACK
- when offer is received with 100rel response
- answer MUST be sent with PRACK
- when offer is received with PRACK or UPDATE
- answer MUST be sent with 2XX response to PRACK or UPDATE
Offer or answer in PRACK MUST be processed even if we have already sent 2XX
to INVITE.
The rules for receiving answer:
- if offer was sent in INVITE, first session description in any non-error
response to INVITE is treated as the answer
- if offer was sent in 2XX response, session description in ACK is answer
- if offer was sent in 100rel response, session description in PRACK is
answer
- if offer was sent in PRACK or UPDATE, session description in 2XX
response is answer
Rules for situations when endpoint MUST ignore the SDP:
- If offer was sent in INVITE, only the first session description in any
non-error (1XX or 2XX) response to INVITE is processed, rest are ignored
- If no offer was sent in 2XX response to INVITE, SDP in ACK is ignored
- If no offer was sent in PRACK, SDP in response to it is ignored
- If no offer was sent in UPDATE, SDP in response to it is ignored
> Message: 1
> Date: Thu, 08 Sep 2011 14:28:58 -0400
> From: Paul Kyzivat <pkyzi...@alum.mit.edu>
> Subject: Re: [Sip-implementors] PRACK Message
> To: sip-implementors@lists.cs.columbia.edu
> Message-ID: <4e69096a.9050...@alum.mit.edu>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> On 9/5/11 12:23 AM, Tarun2 Gupta wrote:
> > Hi Salil
> >
> > As per offer answer model, SDP in PRACK can be an offer as well as an
> answer. Refer RFC 3262
> > and http://tools.ietf.org/html/draft-ietf-sipping-sip-offeranswer-18
> for further details:
>
> The latter is now RFC 6337 (finally!)
>
> Thanks,
> Paul
>
> >
> > Excerpt from the offer-answer draft:
> >
> > Offer Answer RFC Ini Est
> Early
> > -------------------------------------------------------------------
> > 1. INVITE Req. 2xx INVITE Resp. RFC 3261 Y Y N
> > 2. 2xx INVITE Resp. ACK Req. RFC 3261 Y Y N
> > 3. INVITE Req. 1xx-rel INVITE Resp. RFC 3262 Y Y N
> > 4. 1xx-rel INVITE Resp. PRACK Req. RFC 3262 Y Y N
> > 5. PRACK Req. 200 PRACK Resp. RFC 3262 N Y Y
> >
> > Regards,
> > Tarun Gupta
> > Aricent
> >
> > -----Original Message-----
> > From: sip-implementors-boun...@lists.cs.columbia.edu [mailto:
> sip-implementors-boun...@lists.cs.columbia.edu] On Behalf Of Verma, Salil
> (NSN - IN/Gurgaon)
> > Sent: Monday, September 05, 2011 9:46 AM
> > To: sip-implementors@lists.cs.columbia.edu
> > Subject: [Sip-implementors] PRACK Message
> >
> > HI Experts ,
> >
> >
> >
> > Do PRACK Msg contain SDP information . as per Standard theory PRACK is
> > only acknowledgement.
> >
> >
> >
> > But in my case I can see that Prack is coming with SDP .
> >
> >
> >
> > Kindly suggest what can be the reason.
> >
> >
> >
> >
> >
> > Thanks,
> > Best Regards
> > sAlil veRmA
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
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> >
> >
> >
> >
> >
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>
Thanks
Prakash K
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