First of, thank you for all your answers. I am still unsure about the role
of CANCEL for a proxy:
RFC3261 Section 16.7 states:
10. Generate CANCELs
If the forwarded response was a final response, the proxy MUST
generate a CANCEL request for all pending client transactions
associated with this response context.
So doesn't this imply that a Proxy is using CANCEL for specific branch and
must use the received To-Tag if it was received?
E.g.
Proxy 1 being a parallel proxy tries 3 destinations (D1, D2, and D3), D2
returns a 200 OK, while D1 and D3 establish early dialogs (1XX with To-Tag),
shouldn't Proxy 1 issue CANCEL to D1 and D3 with the respective To-Tag that
was received for those branches?
Thank you,
Hai-Dang
-----Original Message-----
From: Christer Holmberg [mailto:[EMAIL PROTECTED]]
Sent: Saturday, August 24, 2002 4:11 AM
To: Hai-dang Pham
Cc: 'Medhavi Bhatia'; [EMAIL PROTECTED]
Subject: Re: [Sip-implementors] RE: Why no To-Tag for Cancel Request?
Hi,
> Isn't CANCEL also used to terminate specific pending branches in a forking
> proxy?
Nope.
> Wouldn't the use of a To-tag help distinguish from the "a dialog
> creating" branch with those that are being cancelled?
It probably would, but if you want to terminate a specific dialog you use
BYE
- with a To tag. That's the rules :)
Regards,
Christer Holmberg
Ericsson Finland
>
>
> -----Original Message-----
> From: Medhavi Bhatia [mailto:[EMAIL PROTECTED]]
> Sent: Friday, August 23, 2002 6:10 PM
> To: Hai-dang Pham; [EMAIL PROTECTED]
> Subject: Re: [Sip-implementors] RE: Why no To-Tag for Cancel Request?
>
> That's because CANCEL is supposed to cancel all dialogs associated
> with a request. It gets forked just like the INVITE. The behavior you
> are referring to is attributed to BYE, which cancels a particular dialog
> only.
>
> ----- Original Message -----
> From: "Hai-dang Pham" <[EMAIL PROTECTED]>
> To: <[EMAIL PROTECTED]>
> Sent: Friday, August 23, 2002 2:15 PM
> Subject: [Sip-implementors] RE: Why no To-Tag for Cancel Request?
>
> Hi all,
>
> I am wondering why CANCEL request (F9) don't use the To-Tag received
> in the 180 response (F8)? This call flow is from
> draft-ietf-sipping-call-flows-00.txt section 3.2.1 Unsuccessful SIP to SIP
> no answer.
>
> User A Proxy 1 Proxy 2 User B
> | | | |
> | INVITE F1 | | |
> |--------------->| INVITE F2 | |
> | (100) F3 |--------------->| INVITE F4 |
> |<---------------| (100) F5 |--------------->|
> | |<---------------| |
> | | | 180 F6 |
> | | 180 F7 |<---------------|
> | 180 F8 |<---------------| |
> |<---------------| | |
> | | | |
> | CANCEL F9 | | |
> |--------------->| | |
> | 200 F10 | | |
> |<---------------| CANCEL F11 | |
> | |--------------->| |
> | | 200 F12 | |
> | |<---------------| |
> | | | CANCEL F13 |
> | | |--------------->|
>
> F8 180 Ringing Proxy 1 -> A
>
> SIP/2.0 180 Ringing
> Via: SIP/2.0/UDP here.com:5060;branch=z9hG4bK74bf9
> ;received=100.101.102.103
> Record-Route: <sip:ss2.wcom.com;lr>, <sip:ss1.wcom.com;lr>
> From: BigGuy <sip:[EMAIL PROTECTED]>;tag=9fxced76sl
> To: LittleGuy <sip:[EMAIL PROTECTED]>;tag=314159
> Call-ID: [EMAIL PROTECTED]
> CSeq: 1 INVITE
> Contact: <sip:[EMAIL PROTECTED]>
> Content-Length: 0
>
> F9 CANCEL A -> Proxy 1
>
> CANCEL sip:[EMAIL PROTECTED] SIP/2.0
> Via: SIP/2.0/UDP here.com:5060;branch=z9hG4bK74bf9
> Max-Forwards: 70
> From: BigGuy <sip:[EMAIL PROTECTED]>;tag=9fxced76sl
> To: LittleGuy <sip:[EMAIL PROTECTED]>
> Call-ID: [EMAIL PROTECTED]
> CSeq: 1 CANCEL
> Content-Length: 0
>
> Can somebody direct me to the section(s) in RFC3261 that explains this?
>
> Thanks you,
>
> Hai-Dang
>
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