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

[[e-mail]]

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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