Re: [Sipping] Request for Open discussion about SIP mobility

[Stefano Salsano <[e-mail]>]

Dear Haruki,

thank you for restarting discussion on SIP mobility. I agree with the
importance to discuss this topic in this WG.

I'd like to bring again to the attention of the WG two related internet
drafts that we submitted some time ago and that we've now updated

[1] Requirements for vertical handover of multimedia sessions using SIP 
http://tools.ietf.org/html/draft-niccolini-sipping-siphandover-03

[2] A solution for vertical handover of multimedia sessions using SIP 
http://tools.ietf.org/html/draft-salsano-sipping-siphandover-solution-02

Now I would like in particular to focus on the requirements draft [1] 
and to make some comparison with your work.

It seems that the requirements and scenarios we consider are largely
overlapping (while we take different approaches for solutions).

We have in common the idea of letting the Correspondant Node as much as
possible not involved in the seamless handover procedure and the
introduction of some sort of B2BUA to assist in the procedure. We also
share the idea that bi-casting can improve the handover and needs to be
properly managed.

As you have already outlined in your draft, a difference in the
requirements is that you would like not to introduce new
headers/parameters while we allow it.

My point here is that the introduction of the new headers in our
scenario only concerns the handover-capable mobile device and the
intermediate element which is in charge to assist in the handover
procedure. Correspondant Node and all other SIP elements are not touched
anyhow. I feel that in any case there the need to implement a lot of
specicif logic to properly handle the bi-casting (not to mention the
problem of discovery of intermediate element that you deliberately
neglect in your draft to simplify the problem). Therefore the addition
of a new header may not be the biggest issue.

Anyway these aspects could be clarified with some deeper technical
discussion, which I hope can start in the WG.

Best regards,
Stefano

Haruki Izumikawa wrote:
> Hello folks,
> 
> I'd like to have an open discussion about SIP-based mobility in this ML.
> Mobility managements using SIP have been actively studied and developed
> worldwide since "Mobility Support Using SIP" (by Elin and Henning) was
> published. SIP-based mobility would have strong advantages such as its
> great affinity for an application as well as flexibility, i.e., terminal
> mobility can be optimally supported independent from underlying network.
> On the other hand, despite many advantages, it is not used for
> large-scale commercial yet. In addition, the discussion about SIP-based
> mobility in IETF seems to be undynamic.
> These days, a multimode terminal is getting popular. Each access
> networks, e.g., cellular and WLAN, have different characteristics in
> terms of throughput or delay. In such a heterogeneous network, SIP
> becomes more useful tool for mobility management because of its
> flexibility. The quality of a multimedia service can be adaptively
> changed in accordance with a nature of an access networks even after
> changing an access network. I think it is time to resume discussing
> about SIP-based mobility. For your information, I have submitted I-D
> regarding seamless session handoff by SIP-based bicasting.
> http://www.ietf.org/internet-drafts/draft-izumikawa-sipping-sipbicast-01.txt
> I would be happy to hear frank opinions of SIP specialists.
> 
> Best regards,
> 
> Haruki
> 
> 


-- 
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Stefano Salsano
Dipartimento Ingegneria Elettronica
Universita' di Roma "Tor Vergata"
Via del Politecnico, 1 - 00133 Roma - ITALY

http://netgroup.uniroma2.it/Stefano_Salsano/

E-mail  : [e-mail]
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Office  : (Tel.) [phone]  (Fax.) [phone]
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