Subject: Re: [MEDIACTRL] SBC traversal - not "if", but "when"

From: Sukanta ganguly <[email-masked]>
Date: Fri, 19 Oct 2007 06:27:08 -0700 (PDT)

Interesting, without a new header how do you think it should work. This would keep the existing solutions compatible.

SG

----- Original Message ----
From: Steve Buko <[email-masked]>
To: Chris Boulton <[email-masked]>; "[email-masked]" <[email-masked]>
Sent: Friday, October 19, 2007 5:26:30 AM
Subject: RE: [MEDIACTRL] SBC traversal - not "if", but "when"

1) Should SBC's and the like be taken into consideration in the core Sip Control Framework?

[Steve Buko] IMO, no.

2) There is currently a mechanism for identifying a dialog within the
Control Framework.  At the moment we currently use the dialog
identifiers to identify a dialog.  Is this an appropriate mechanism?
Your answer to this should be influenced by the answer to 1) as in the
default case it does not work through SBC's that muck about with stuff.
If you are saying that you would like a different mechanism - please
suggest a strawman proposal to be considered.

[Steve Buko]  I agree with Chris on this one.  The use of the "tags" may not be perfect, but adding a new header isn't any better IMO.

|-----Original Message-----
|From: Chris Boulton [mailto:[email-masked]]
|Sent: Friday, October 19, 2007 6:30 AM
|To: Chris Boulton; Christer Holmberg; Spencer Dawkins;
[email-masked]
|Subject: RE: [MEDIACTRL] SBC traversal - not "if", but "when"
|
|[Chris Boulton] [responding as a contributor].
|
|1) Should SBC's and the like be taken into consideration in the core Sip
|Control Framework?
|
|[Chris Boulton] No.
|
|2) There is currently a mechanism for identifying a dialog within the
|Control Framework.  At the moment we currently use the dialog
|identifiers to identify a dialog.  Is this an appropriate mechanism?
|Your answer to this should be influenced by the answer to 1) as in the
|default case it does not work through SBC's that muck about with stuff.
|If you are saying that you would like a different mechanism - please
|suggest a strawman proposal to be considered.
|
|[Chris Boulton] I am not yet convinced that changing how we do this will
|benefit the SBC case.  The tags will change which will cause a problem -
|just adding a new SIP header will cause a problem (no guarantee it will
|make it through).  It is my view that if this is to pass through an SBC
|then the SBC needs to be aware what is going on.  For that I think we
|need an extension that maps both sides of the game - as it does today
|for SIP and RTP.  I don't think a half way house will please anyone.
|
|The one advantage I can see from having a unique identifier explicitly
|expressed in the message is that an SBC acting as a B2BUA (for Control
|Channel as well) would not have to muck with Control Framework messages.
|This is quite appealing.
|
|Could this unique-ID be an SDP attribute rather than being inferred from
|the tags?
|
|Chris.
|
|
|
|
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[email-masked]
|https://www1.ietf.org/mailman/listinfo/mediactrl
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---

From: Steve Buko <[email-masked]>
Date: Fri, 19 Oct 2007 10:53:29 -0700

The currently defined method for referencing active SIP dialogs is using a "Dialog-ID'.

Per draft-ietf-mediactrl-sip-control-framework-00.txt the "Dialog-ID' is constructed

"by concatenating the Local-tag, Call-ID and Remote-tag"

If I'm reading this tread correctly, the concern is whether SBC's will modify the "tags".
Adding another SIP header to work around the fact that SBC's may modify the "tags" doesn't seem to be any more reliable than using the "tags".
There still isn't a guarantee that the new header will make it intact to the MS.

From: Sukanta ganguly [mailto:[email-masked]]
Sent: Friday, October 19, 2007 9:27 AM
To: Steve Buko; Chris Boulton; [email-masked]
Subject: Re: [MEDIACTRL] SBC traversal - not "if", but "when"

SG
----- Original Message ----
From: Steve Buko <[email-masked]>
To: Chris Boulton <[email-masked]>; "[email-masked]" <[email-masked]>
Sent: Friday, October 19, 2007 5:26:30 AM
Subject: RE: [MEDIACTRL] SBC traversal - not "if", but "when"

[Steve Buko] IMO, no.

|From: Chris Boulton [mailto:[email-masked]<mailto:[email-masked]>]
[email-masked]<mailto:[email-masked]>
[email-masked]<mailto:[email-masked]>

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---

From: "Chris Boulton" <[email-masked]>
Date: Mon, 22 Oct 2007 10:02:27 +0100

The currently defined method for referencing active SIP dialogs is using
a "Dialog-ID'.

Per draft-ietf-mediactrl-sip-control-framework-00.txt the "Dialog-ID' is
constructed 
"by concatenating the Local-tag, Call-ID and Remote-tag"

If I'm reading this tread correctly, the concern is whether SBC's will
modify the "tags".

Adding another SIP header to work around the fact that SBC's may modify
the "tags" doesn't seem to be any more reliable than using the "tags".

There still isn't a guarantee that the new header will make it intact to
the MS.

[Chris Boulton] Agreed - and put far more clearly that me :-).  The only
way is guarantee this is to have an extension.

Chris.

Interesting, without a new header how do you think it should work. This
would keep the existing solutions compatible.

SG

----- Original Message ----
From: Steve Buko <[email-masked]>
To: Chris Boulton <[email-masked]>; "[email-masked]"
<[email-masked]>

1) Should SBC's and the like be taken into consideration in the core Sip
Control Framework?

[Steve Buko] IMO, no.

[Steve Buko]  I agree with Chris on this one.  The use of the "tags" may
not be perfect, but adding a new header isn't any better IMO.

|1) Should SBC's and the like be taken into consideration in the core
Sip
|[Chris Boulton] I am not yet convinced that changing how we do this
will
|benefit the SBC case.  The tags will change which will cause a problem
-
|Channel as well) would not have to muck with Control Framework
messages.
|Could this unique-ID be an SDP attribute rather than being inferred
from