Subject: RE: [Sip-implementors] [Sipping] Proxy acting as UAS -- CANCEL scenario

From: nithya kumar <[email-masked]>
Date: Tue, 05 Jun 2007 18:07:25 +0530

While sending cancel itself, will specify the transaction that to be
canceled.(suppose consider Invite transaction have to be canceled.cancel
will sent with same transaction ID as of INvite). If cancel is successfully
reached UAS.then UAS will reply with 200 ok.Then will send 487 Request
Treminated for the same.

     UAC                            UAS

> Invite                          Invite>    

                ------------

>cancel                           cancel>

<200 ok                            200 ok<

<487 Req Ter                      <487 Req Treminated

    Note : cancel should be sent before final response.if not cancel has no
effect.

Please correct me if wrong....

Regards,

Nithya Kumar.

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-----Original Message-----
From: [email-masked]
[mailto:[email-masked]] On Behalf Of Prabhakaran,
Manikantan
Sent: Tuesday, June 05, 2007 12:10 PM
To: Iliff, Tina; [email-masked]; [email-masked];
Avasarala Ranjit-A20990
Subject: Re: [Sip-implementors] [Sipping] Proxy acting as UAS -- CANCEL
scenario

Hi,

    Receiving a 200 OK for the CANCEL only ensures the CANCEL

Transaction has terminated. But what about the INVITE Transaction ? For

the INVITE transaction to be terminated the proxy should responsd with a

487 (Requested Terminated) response.

-Regards

Mani.

________________________________

From: Avasarala Ranjit-A20990 [mailto:[email-masked]] 

Sent: Tuesday, June 05, 2007 11:59 AM

To: Iliff, Tina; [email-masked]; [email-masked]

Subject: RE: [Sipping] Proxy acting as UAS -- CANCEL scenario

Importance: High

Hi

In ur scenarios, SBC cannot receive 100 Trying, but it should receive

180 Ringing from TUA. Ok say SBC does not receive 180, the SBC will

retransmit INVITE for certain times with timer T1).. 

Now say OUA sends CANCEL to proxy and proxy sends 200 OK to OUA - so

here the transaction ends with respect to OUA.

Now Proxy forwards CANCEL to SBC. and 

SBC should send 200 OK to proxy. 

Finally SBC can send CANCEL to TUA 

why should proxy send 487 to OUA?  I don't think it is required

amd why should SBC send 408 for the INVITE that does not exist anymore?

Regards 

Ranjit 

 

________________________________

From: Iliff, Tina [mailto:[email-masked]] 

Sent: Tuesday, June 05, 2007 2:08 AM

To: [email-masked]; [email-masked]

Subject: [Sipping] Proxy acting as UAS -- CANCEL scenario

All, 

RFC3261 Section 16 states the following regarding Proxy Behavior: 

Being a proxy is a logical role for a SIP element. When a request

arrives, an element that can play the role of a proxy first decides

if it needs to respond to the request on its own. For instance, the

request may be malformed or the element may need credentials from the

client before acting as a proxy. The element MAY respond with any

appropriate error code. When responding directly to a request, the

element is playing the role of a UAS and MUST behave as described in

Section 8.2.

Please consider the following call flow scenario: 

OUA sends INVITE to Proxy 

Proxy sends 100 Trying to OUA 

Proxy routes INVITE to SBC 

SBC sends 100 Trying to Proxy 

SBC routes INVITE to TUA 

SBC does not receive 100 Trying from TUA and retransmits INVITE several

times   

OUA sends CANCEL to Proxy 

Proxy responds to CANCEL with 200OK 

Proxy routes CANCEL to SBC 

SBC does not route CANCEL to TUA 

A CANCEL timer on Proxy pops and Proxy sends 487 for INVITE request to

OUA 

Several seconds elapse and Timer B pops on the SBC and it sends a 408

back to the Proxy for the INVITE request 

The proxy does not ACK the 408 response; therefore, the SBC retransmits

the 408 for 64*T1 seconds 

Note:  The SBC is acting as a proxy and not a B2BUA 

Question:  Is the proxy behaving correctly by sending the 487 response

to the INVITE request on its own? 

Regards, 

Tina Iliff 

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---

From: nithya kumar <[email-masked]>
Date: Tue, 05 Jun 2007 18:07:25 +0530

UAC                            UAS

                ------------

<200 ok                            200 ok<

 

Regards,

Nithya Kumar.

-----Original Message-----

Hi,

 

-Regards

Mani.

Importance: High

Hi

 

Regards 

Ranjit 

 

 

All, 

Section 8.2.

SBC routes INVITE to TUA 

times   

OUA 

Regards, 

Tina Iliff