Subject: RE: [Sipping] SBC Requirements doc

From: "Christian Stredicke" <[email-masked]>
Date: Wed, 2 Feb 2005 10:56:23 +0100

The document is a good start in the whole discussion. Obviously you know
what you are talking about.
 
I am missing a couple of things that (AFAIK) important to SBC. A few
practical questions that come to my mind when thinking about SBC:

*	
	How are NAT bindings refreshed? Is there anything that a UA can
do to make life easier? Who detects what a UA is behind NAT?
*	How does the SBC indicate what QoS methods it supports and what
the UA should deliver (statistics)? Having a simple Rx/Tx statistics in
the BYE message is already a great improvement.
*	
	How are dialogs kept alive? What if someone just pulls the plug?
*	
	Who does media path optimization? The SBC or the UA (ICE)?
*	How is failover being implemented? Again, is there anything in
the UA that can make the job easier?
*	
	
	Should there be a standardized management interface for SBC?
Maybe in a large network operators want to have different SBC products
with a similar way to manage them. A MIB could be helpful here.

Christian

________________________________

	From: [email-masked] [mailto:[email-masked]]
On Behalf Of Medhavi Bhatia
	Sent: Tuesday, February 01, 2005 5:17 PM
	To: [email-masked]
	Subject: [Sipping] SBC Requirements doc

	Based on discussions at the last DC meeting, we have posted a
requirements draft for folks who are interested:

ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-bhatia-sipping-s
bc-00.txt

	Abstract:

	  "Typical policy implemented at network border deals with
security and

	   enforcement of service level agreements at the network level.
For

	   multimedia sessions, such policy can be applied not only at
higher

	   layers but can be provided in a more granular and extended
fashion.

	   A Session Border Control (SBC) entity is a network
intermediary

	   located at the administrative boundary of the network for
policy

	   enforcement on multimedia sessions.  The focus of this
document is

	   the SIP specific requirements for SBCs.  This document  does
not

	   specify any architectural requirments for SBCs.
Architectures such

	   as specified in [1] may be used."

	-Medhavi.

	Medhavi Bhatia

	Chief Architect

	NexTone Communications

	www.nextone.com <http://www.nextone.com/>  

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---

From: "Medhavi Bhatia" <[email-masked]>
Date: Thu, 3 Feb 2005 23:24:08 -0500

Christian,

My responses inline.

  _____  

From: Christian Stredicke [mailto:[email-masked]] 
Sent: Wednesday, February 02, 2005 4:56 AM
To: Medhavi Bhatia
Cc: [email-masked]
Subject: RE: [Sipping] SBC Requirements doc

*	How are NAT bindings refreshed? Is there anything that a UA can do
to make life easier? Who detects what a UA is behind NAT?

[MB] Any of the NAT Traversal mechanisms can be used. Clearly they need to
be used only when the SBC inserts itself in the media path.

*	How does the SBC indicate what QoS methods it supports and what the
UA should deliver (statistics)? Having a simple Rx/Tx statistics in the BYE
message is already a great improvement.
*	How are dialogs kept alive? What if someone just pulls the plug?

[MB] Session timers could be used. If the topology is such that the
registrar is in the SBC Network and UEs in the external network, the
registration event package could be useful too. I am thinking that this
should be a higher level requirement too. An SBC must clearly have a
mechanism for session monitoring.

*	Who does media path optimization? The SBC or the UA (ICE)?

[MB] Both. The SBC implements the traffic management policy of the service
provider's network. It will implement its own media path optimization
techniques. Clearly they will override the UAs (ICE etc) if they contradict.
The traffic management section should talk about this.

*	How is failover being implemented? Again, is there anything in the
UA that can make the job easier?
*	Should there be a standardized management interface for SBC? Maybe
in a large network operators want to have different SBC products with a
similar way to manage them. A MIB could be helpful here.

Christian

  _____  

From: [email-masked] [mailto:[email-masked]] On Behalf
Of Medhavi Bhatia
Sent: Tuesday, February 01, 2005 5:17 PM
To: [email-masked]
Subject: [Sipping] SBC Requirements doc

Based on discussions at the last DC meeting, we have posted a requirements
draft for folks who are interested:

ftp://ftp.rfc-editor.org/in-notes/internet-drafts/draft-bhatia-sipping-sbc-0
0.txt

Abstract:

  "Typical policy implemented at network border deals with security and

   enforcement of service level agreements at the network level.  For

   multimedia sessions, such policy can be applied not only at higher

   layers but can be provided in a more granular and extended fashion.

   A Session Border Control (SBC) entity is a network intermediary

   located at the administrative boundary of the network for policy

   enforcement on multimedia sessions.  The focus of this document is

   the SIP specific requirements for SBCs.  This document  does not

   specify any architectural requirments for SBCs.  Architectures such

-Medhavi.

Medhavi Bhatia

Chief Architect

NexTone Communications