Subject: Using COPS for VoIP call initiation

From: Arie Nimkovsky <[email-masked]>
Date: Tue, 24 Apr 2001 18:52:04 +0200

Hello,

Our system uses a layer-2 (bridge) entity through which VoIP calls flow.
This bridge should supply resources relevant to VoIP. 
A Call Agent which manages the call signaling will inform the bridge about
the required resources for each call, and the bridge will reply the Call
Agent whether it has the requested resources. If it has not - the call
request be dropped by the Call Agent.
My question:
Is COPS suitable for such message exchange?  Who is the client and who is
the server in this case? It seems to me that the client/server roles are
reversed here - the entity that knows about the call in progress is the Call
Agent so it is the candidate for the client (PEP) role, however the actual
admission will make the bridge, so from this aspect IT should be the policy
enforcing point.
Can someone to enlighten me on this? If not COPS - may be there is some
other more suitable protocol for the stated purposes?

Thanks,
Arie Nimkovsky

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From: "Iliff, Tina" <[email-masked]>
Date: Tue, 24 Apr 2001 16:03:51 +0000

Arie,

It sounds as though COPS Usage for RSVP may be suitable for the scenario
which you have described below.  Please reference RFC 2749.
Tina Iliff

	-----Original Message-----
	From:	Arie Nimkovsky [mailto:[email-masked]]
	Sent:	Tuesday, April 24, 2001 11:52 AM
	To:	[email-masked]
	Subject:	Using COPS for VoIP call initiation

	Hello,

	Our system uses a layer-2 (bridge) entity through which VoIP calls
flow.
	This bridge should supply resources relevant to VoIP. 
	A Call Agent which manages the call signaling will inform the bridge
about
	the required resources for each call, and the bridge will reply the
Call
	Agent whether it has the requested resources. If it has not - the
call
	request be dropped by the Call Agent.
	My question:
	Is COPS suitable for such message exchange?  Who is the client and
who is
	the server in this case? It seems to me that the client/server roles
are
	reversed here - the entity that knows about the call in progress is
the Call
	Agent so it is the candidate for the client (PEP) role, however the
actual
	admission will make the bridge, so from this aspect IT should be the
policy
	enforcing point.
	Can someone to enlighten me on this? If not COPS - may be there is
some
	other more suitable protocol for the stated purposes?

	Thanks,
	Arie Nimkovsky

**********************************************************************
	The information transmitted is intended only for the person or
entity to
	which it is addressed and may contain confidential and/or privileged
	material.  Any review, retransmission, dissemination or other use
of, or
	taking of any action in reliance upon, this information by persons
or
	entities other than the intended recipient is prohibited.   If you
received
	this in error (whether inadvertently addressed to you, or if
forwarded to
	you by a recipient), please contact the sender and delete the
material from
	any computer.

	This footnote also confirms that this email message has been swept
by
	VYYO's Virus Scan Systems for the presence of computer viruses.

---

From: "Iliff, Tina" <[email-masked]>
Date: Tue, 24 Apr 2001 16:10:58 +0000

Arie,

RSVP between the Call Agent and the Bridge and COPS-RSVP between the Bridge
and a Remote Policy Decision Point (PDP) may be suitable.  However, only
RSVP between the Call Agents and the Bridges and from Bridge to Bridge or
from Bridge to Router may be suitable if the Bridges have Local Policy
Decision Point capability.  For RSVP, please reference RFC 2205 and 2210.
Tina Iliff

	-----Original Message-----
	From:	Arie Nimkovsky [mailto:[email-masked]]
	Sent:	Tuesday, April 24, 2001 11:52 AM
	To:	[email-masked]
	Subject:	Using COPS for VoIP call initiation

	Hello,

	Thanks,
	Arie Nimkovsky

---

From: "Gross, Gerhard" <[email-masked]>
Date: Wed, 25 Apr 2001 13:43:33 -0700

Arie,

We have implemented a COPS extension for SIP in house
which does something very similar to what you describe.
The SIP proxy (call agent) is the PEP and a policy server
is contacted for a policy based admission decision. The
policy server may base its decision on a variety of criteria.

Standards work is ongoing:
http://www.ietf.org/internet-drafts/draft-gross-cops-sip-01.txt
http://www.ietf.org/internet-drafts/draft-gross-sipaq-01.txt

Gery

> Sent: Tuesday, April 24, 2001 9:52 AM
> To: [email-masked]
> *********************************************************************