RE: 3GPP Analysis revision -10 (resolving IESG comments)

[<juha.wiljakka@nokia.com>]

Gabor,

I share your concerns...that's why I wrote "I am still a bit unsure about the text..." in my e-mail. At this point it would be very important to get comments from Allison (that has suggested text for IMS scenario 1).

Some other comments below:

-----Original Message-----
From: Bajko Gabor
Sent: 28 May, 2004 18:52

A few questions to the text in the draft:

In section 4.1 it is written: "... this approach would not take advantage of SIP's ability to use proxy routing"

I can not really see what kind of ability is lost here. What exactly the authors think it is lost?

  JW: This is also a point that is unclear for me. Allison, can you comment?

Further down in the same section:

"IMS data is time-sensitive ... Alternatives include 
    routing to a transcoder, whose task is to terminate an IPv6 stream 
    and start an IPv4 stream"

I failed to understand the advantage of a transcoder to a NAT-PT. Why is an alternative to process a packet also at application layer when you can do it at IP layer? Also, time sensitiveness is not always an issue...

  JW: Right... Time sensitiviness depends on whether you are using real-time services or non-real-time (IMS) services. Can Allison clarify the transcoder point?

Then:

"The authors 
    recommend that a detailed solution for the general SIP/SDP/media 
    IPv4/IPv6 transition problem will be specified as soon as possible 
    as a task within the SIP WGs in the IETF. "

The above statement sounds strange for me. It could be instead said that this document describes a solution based on SIP-ALG and NAT-PT, and other solutions might (or might not) become available later.

  JW: I think that the recommendation to specify a future solution is valid and the ball clearly goes to the SIPpish wgs. But in *my* opinion, we also need a higher level solution in this document. If we take the (SIP-ALG + translator) solution out (or remove details), this document does not provide much useful information for IMS scen 1... 

Thanks,
	 -Juha-