Re: [straw] FW: New Version Notification for draft-ram-straw-b2bua-feature-tag-00.txt

["Ram Mohan R (rmohanr)" <[e-mail]>]

Hi Ranjit,

Agree. There can be multiple roles for B2BUA and hence different
capabilities.

Ram

-----Original Message-----
From: "[e-mail]" <[e-mail]>
Date: Friday, 31 July 2015 8:46 pm
To: Cisco Employee <[e-mail]>
Cc: Paul Kyzivat <[e-mail]>, "[e-mail]" <[e-mail]>
Subject: Re: [straw] FW: New Version Notification for
draft-ram-straw-b2bua-feature-tag-00.txt

>Hi Ram
>
>I agree that B2BUA can multiple roles for different scenarios - but it
>could also play multiple roles for a particular scenario - like for a
>particular session, it could play the role of both signaling and media
>relay. Then both need to be indicated. So then the syntax could be
>
>Contact: <sip:[e-mail]>;audio;video;
>          methods="INVITE,BYE,OPTIONS,ACK,CANCEL";
>          +sip.isSignalingB2BUA, +sip.isMediaAwareRelayB2BUA
>
>
>This means that the B2BUA can act as both signaling and media relay for
>this scenario and also shows its capabilities to act as both.
>
>Regards
>Ranjit
>
>On 2015-07-20 6:52 am, Ram Mohan R (rmohanr) wrote:
>> Hi Paul,
>> 
>> Sorry for delay. See inline
>> 
>> -----Original Message-----
>> From: straw <[e-mail]> on behalf of Paul Kyzivat
>> <[e-mail]>
>> Date: Monday, 6 July 2015 6:47 pm
>> To: "[e-mail]" <[e-mail]>
>> Subject: Re: [straw] FW: New Version Notification for
>> draft-ram-straw-b2bua-feature-tag-00.txt
>> 
>>> Ram,
>>> 
>>> I am puzzled by this. I can't figure out when/how it would be used, or
>>> if/how it relates to RFC6809 (proxy-feature).
>>> 
>>> My problem is fundamentally whether the devices carrying this tag are
>>> to
>>> be viewed as endpoints or intermediaries.
>> 
>> These devices are primarily intermediary devices [ B2BUAs of types in
>> RFC
>> 7092].
>> 
>>> For the properties being
>>> described to be useful, I think one must view the device as an
>>> intermediary, that is somehow masking/modifying the intrinsic
>>> properties
>>> of the *actual* endpoint. Yet feature tags (callee capabilities)
>>> should
>>> be viewed as describing the target of communication.
>> 
>> Agree. Initially I had looked at RFC 3840 capabilities (some of them
>> like
>> isFocus which is a special case of middle box terminating sessions) and
>> thought 3840 would fit in to indicate the B2BUA capabilities. After
>> reading RFC 6809 I think that is more relevant and each B2BUA in the
>> path
>> can add a fci header with its type and so when the UA receives the
>> INVITE
>> it will see the list of fci headers with the top most being the closest
>> to
>> UA receiving the message.
>> 
>> The goal of this draft is for a UA to know the different types of B2BUA
>> [
>> with in the scope of RFC 7092 types] between itself and the
>> destination.
>> What the UA does by looking at the type of B2BUA is not in scope here.
>> 
>> Ram
>>> 
>>> RFC6809 provides a way of describing properties of intermediaries on
>>> the
>>> signaling (and potentially also the media) path. Perhaps this new
>>> property belongs there instead.
>>> 
>>> Another way to use a B2BUA is for me, as a user, to use a B2BUA as a
>>> foundation to build a virtual user agent, composed of one or more
>>> other
>>> UAs. That seems to fit your model. But in that case, other UAs
>>> interacting with it don't need to know that it is a B2BUA. Rather,
>>> they
>>> only need to know what capabilities it presents to the world. The fact
>>> that it is a B2BUA is simply an implementation detail.
>>> 
>>> 	Thanks,
>>> 	Paul
>>> 
>>> On 7/6/15 12:07 PM, Ram Mohan R (rmohanr) wrote:
>>>> Hi All,
>>>> 
>>>>   We have published a new draft that extends the User Agent
>>>> capabilities
>>>> specification(RFC 3840) to allow
>>>>     indication of Back-to-Back User Agent (B2BUA) types.
>>>> The motivation for this draft came out  of IESG review and subsequent
>>>> discussions of [I-D.ietf-straw-b2bua-stun] where it was pointed
>>>> that there is no existing mechanisms for B2BUA to indicate its
>>>> presence
>>>> except for special cases like Focus.
>>>> 
>>>> Please review and provide your inputs.
>>>> 
>>>> Regards,
>>>> Authors
>>>> 
>>>> -----Original Message-----
>>>> From: "[e-mail]" <[e-mail]>
>>>> Date: Monday, 6 July 2015 8:08 pm
>>>> To: Cisco Employee <[e-mail]>, "Tirumaleswar Reddy
>>>> (tireddy)"
>>>> <[e-mail]>, "Gonzalo Salgueiro (gsalguei)"
>>>> <[e-mail]>,
>>>> "Gonzalo Salgueiro (gsalguei)" <[e-mail]>, "Tirumaleswar
>>>> Reddy
>>>> (tireddy)" <[e-mail]>, Cisco Employee <[e-mail]>
>>>> Subject: New Version Notification for
>>>> draft-ram-straw-b2bua-feature-tag-00.txt
>>>> 
>>>>> 
>>>>> A new version of I-D, draft-ram-straw-b2bua-feature-tag-00.txt
>>>>> has been successfully submitted by Ram Mohan Ravindranath and posted
>>>>> to
>>>>> the
>>>>> IETF repository.
>>>>> 
>>>>> Name:		draft-ram-straw-b2bua-feature-tag
>>>>> Revision:	00
>>>>> Title:		A Session Initiation Protocol (SIP) Feature Tag for
>>>>> Back-to-Back
>>>>> User Agents (B2BUAs)
>>>>> Document date:	2015-07-06
>>>>> Group:		Individual Submission
>>>>> Pages:		8
>>>>> URL:
>>>>> 
>>>>> 
>>>>>https://www.ietf.org/internet-drafts/draft-ram-straw-b2bua-feature-tag
>>>>>-0
>>>>> 0.
>>>>> txt
>>>>> Status:
>>>>> https://datatracker.ietf.org/doc/draft-ram-straw-b2bua-feature-tag/
>>>>> Htmlized:
>>>>> https://tools.ietf.org/html/draft-ram-straw-b2bua-feature-tag-00
>>>>> 
>>>>> 
>>>>> Abstract:
>>>>>    The User Agent capabilities specification allows Session
>>>>> Initiation
>>>>>    Protocol (SIP) User Agents to convey their capabilities and
>>>>>    characteristics to other User Agents and to the registrar for its
>>>>>    domain.  This information is conveyed as parameters of the
>>>>> Contact
>>>>>    header field.  Amongst those capabilities are the type of User
>>>>> Agent
>>>>>    that is available at a SIP Uniform Resource Identifier (URI).
>>>>> This
>>>>>    document extends the User Agent capabilities specification to
>>>>> allow
>>>>>    indication of Back-to-Back User Agent (B2BUA) types.
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> 
>>>>> Please note that it may take a couple of minutes from the time of
>>>>> submission
>>>>> until the htmlized version and diff are available at tools.ietf.org.
>>>>> 
>>>>> The IETF Secretariat
>>>>> 
>>>> 
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>>> 
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