Subject: RE: [Sipping] Re: draft-littlefield-sipping-mgmt-event-01.txt

From: "Sumanth Channabasappa" <[email-masked]>
Date: Sun, 5 Nov 2006 17:58:56 -0700

Comments inline...

From: Josh Littlefield [mailto:[email-masked]] 
Hi Paul,
Paul Kyzivat wrote:
> Did you consider, as an alternative, simply sending a REFER to the 
> device, with a Refer-To: snmp:whatever ?

I guess that's an interesting idea for what I've defined as the NOTIFY
end of this (assuming we can define sufficiently descriptive URIs for
the mgmt protocols).

It leaves open the question of how the UA indicates it's availability
and interest in being managed, and its mgmt capabilities.  The SUBSCRIBE
from the managed entity provides a way to do that, but they REFER would
seem to arrive sort of spontaneously from the management station.
[S] Managed SIP UAs usually have knowledge of the management stations
authorized to manage them. This can happen via pre-or dynamic
configuration, but in most cases will be known to the client.

The REFER may work for the initial setup, but the SUBSCRIBE/NOTIFY
framework provides a slightly richer behavior, IMHO: a) it allows for
the 'client' to SUBSCRIBE and maintain the subscription until interested
(or configured otherwise) b) Allows for the SIP infrastructure to send a
NOTIFY (within a subscription) when communication is required or
anything changes. The latter (b) could be achieved using REFER, but can
we also achieve the former?

One could use REFER from an authenticated source as a means to configure
the client with the Management Station information, which would then
proceed to SUBSCRIBE to the information - if that makes sense?

Was the REFER considered as an option for the SIPPING-CONFIG framework?

Maybe that could be solved through presence (this is getting out of my
depth), but I'm not sure how much infrastructure is desirable to be
pulled into solving this problem.
[S] Unsure if this can be solved using Presence. Can you provide more
details?

Thanks

- S

> 
>     Paul
> 
> [email-masked] wrote:
>> A New Internet-Draft is available from the on-line Internet-Drafts 
>> directories.
>>
>>
>>     Title        : A Management Request Event Package for the Session

>> Initiation Protocol (SIP)
>>     Author(s)    : J. Littlefield
>>     Filename    : draft-littlefield-sipping-mgmt-event-01.txt
>>     Pages        : 19
>>     Date        : 2006-10-22
>>     
>> In many environments, firewall, NAT and IP addressing issues make
>>    remote management of devices containing SIP user agents difficult.
>>    This document defines a SIP event package for notifying a user
agent
>>    that it should initiate a session with a management entity for
>>    management operations.  This type of "call-home" management avoids
>>    the need to maintain persistent TCP connections, or generate
>>    additional STUN traffic, with the management entity.  This event
>>    package is intended not to tunnel management protocols or
otherwise
>>    provide management itself, but instead to provide a means for
>>    signaling a SIP UA that a management session is desired.
>>
>> A URL for this Internet-Draft is:
>> http://www.ietf.org/internet-drafts/draft-littlefield-sipping-mgmt-ev
>> ent-01.txt
>>
>>
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Josh Littlefield                                  Cisco Systems, Inc.
[email-masked]                             1414 Massachusetts Avenue
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