Subject: RE: [Sipping] Fixed Mobile Convergence (draft-yafan-fmc-arch-00.txt)

From: "Yafan An" <[email-masked]>
Date: Tue, 22 Aug 2006 12:22:40 -0700

-----Original Message-----
From: Arjun Roychowdhury [mailto:[email-masked]] 
Sent: Tuesday, August 22, 2006 7:12 AM
To: Yafan An
Cc: [email-masked]
Subject: Re: [Sipping] Fixed Mobile Convergence
(draft-yafan-fmc-arch-00.txt)

Yafan,
Just noticed this post.

Comments while reading through the draft:

General_1:
* This is not really an over-arching FMC draft. It does not factor in
GANs such as WiMAX / WLAN/DSL  since the network reference model
depicts MSC/VLR etc. which may not exist depending on the access
network being connected to.
[Yafan An] It should have an "IP access" cloud which represents
WLAN/WiMax/Broadband etc. This draft addresses some convergence issues
between these IP access networks and the cellular network.

Similarly, the identification tokens seem to be specific to the celluar
world.
Similary, the document contains many references to IMSI/MSISDN which
again assumes interworking of an existing cellular network to a VoIP
network. If we assume a PC soft-client on a desktop over WLAN needs to
interwork, what will its IMSI be ? This comment comes due to the scope
specified in your Abstract - I think the rest of the document has a
much more restricted scope than the abstract quotes
[Yafan An] For Dual Mode Handset (DMH), we should assume that an IMSI is
always available for cellular access. A PC soft client that is not a
dual mode handset, is outside the scope of this draft. There are other
works which addresses transfers between SIP UAs, which I am currently
evaluating.

General_2:
The benefits of this architecture over proposed interworking
architectures by 3G is unclear to me. Can you please state the
advantages ? I  noticed that you also propose network initiated
handover - this , afaik, is work under investigation as well with VCC
and MiH (802.21)
[Yafan An] I agree, this will be address in future updates.

regds
arjun

* I have a fundamental problem with the MP-CSCF. It does not exist
today and does not fit neatly into the defined 3G architecture. Most
vendors I know have ready P-CSCFs and S-CSCFs. Pushing the anchoring
function to the AS node (as VCC does) fits well into this model -
mobility anchoring can be 'added' as an application node. Putting an
MP-CSCF upfront means it needs to support all the published interfaces
of the P-CSCF and more.
[Yafan An] MP-CSCF is a specialized P-CSCF. You have a good argument
here. I am considering separating the mobility piece out and name it
separately.

* 3.2: PSI is referred to as the 'Public Service Identifier' in the
3G/IMS world - you use it to refer to 'pkt switched i/d'. (also CSI is
referred to as the much debated 'Communication Service Identifier' ).
Consider using common terminologies - PS/CS
[Yafan An] Point taken.

* 3.2.1: I am confused why you call the 'S-CSCF' a soft-switch (3.2.1)
. This seems to indicate a product configuration. From a
standardization perspective, an S-CSCF does not need to have
traditional soft-switching capabiltiies nor class-5 features as you
mention. The S-CSCF is supposed to execute the iFC and forward to the
appropriate AS/MGCF for execution of relevant services.
[Yafan An] Point taken. Will add AS into the picture and clarify related
text.

* 6.2: I believe P-Access-Network-Info and P-Visited-Network-ID could
be used instead of overloading existing SIP headers.
[Yafan An] P-Visited-Network-ID was considered. However, it was defined
in RFC3455 for conveying ID to the home network. The coding of it may
not be as "free style" as the "Organization" field for display purposes.

On 8/21/06, Yafan An <[email-masked]> wrote:
>
>
>
> Dear Sipping Enthusiasts:
>
> If you have not noticed the ietf drafts, I'd like to invite you to
read and
> comment on the submitted draft. You can send your comments to me or
the
> sipping list.
>
> Thank you.
>
> Yafan
>
>
>         Title           : An Architecture Framework for Fixed Mobile
> Convergence Using SIP as Access Call Control Protocol
>
>         Author(s)       : Y. An
>
>         Filename        : draft-yafan-fmc-arch-00.txt
>
>         Pages           : 32
>
>         Date            : 2006-7-28
>
>
>
> This document describes an architecture framework for achieving
>
> converged mobile services across alternative radio access networks
>
> (GAN, or Generic Access Network), such as WLAN, WiMax, and the
>
> cellular network, while utilizing SIP for media session control
>
> between the dual mode handset (DMH) and a network SIP proxy.  The key
>
> benefits of this architecture include (1) fast and flexible service
>
> deployment in the IP domain, and (2) allow seamless voice call
>
> continuity services across IP and circuit-switched cellular domains.
>
>
> A URL for this Internet-Draft is:
>
> http://www.ietf.org/internet-drafts/draft-yafan-fmc-arch-00.txt
>
>
>
>
>         YAFAN AN - CHIEF ARCHITCET
> T: 408.855.2957  M: 510.386.2647  F: 408.855.2978
> SERVICES WITHOUT BOUNDARIES
>
>
>
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>

-- 
Arjun Roychowdhury

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