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

From: <[email-masked]>
Date: Fri, 28 May 2004 17:51:39 +0200

Hello,

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?

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...

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.

/Gabor

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

Hi all,

I finally managed to compose revision -10 of the 3GPP Analysis document. The draft can be found here:
http://www.ietf.org/internet-drafts/draft-ietf-v6ops-3gpp-analysis-10.txt

The document now *should* resolve IESG discuss comments, the major changes compared to -09 are the following:
- summary/recommendations section
- IMS scenario 1 text (based on Allison Mankin's text) - I am still a bit unsure about the text...
- editorial changes / proofreading done by Spencer Dawkins

This is what I wrote in the summary/recommendations section:
------------
    This document has analyzed five GPRS and two IMS IPv6 transition 
    scenarios. Numerous 3GPP networks are using private IPv4 addresses 
    today, and introducing IPv6 is an important thing. The two first 
    GPRS scenarios and both IMS scenarios are seen the most relevant. 
    The authors summarize some main recommendations here: 
       - Dual-stack UEs are recommended instead of IPv4-only or IPv6-
         only UEs. It is important to take care that the applications 
         in the UEs support IPv6. IPv6-only UEs can become feasible 
         when IPv6 is widely deployed in the networks, and most 
         services work on IPv6. 
       - It is recommended to activate an IPv6 PDP context when 
         communicating with an IPv6 peer node and an IPv4 PDP context 
         when communicating with an IPv4 peer node. 
       - IPv6 communication is preferred to IPv4 communication going 
         through IPv4 NATs to the same dual stack peer node. 
       - This document strongly recommends the 3GPP operators to deploy 
         basic IPv6 support in their GPRS networks as soon as possible. 
         That makes it possible to lessen the transition effects in the 
         UEs. 
       - A tunneling mechanism in the UE may be needed during the early 
         phases of the IPv6 transition process. A lightweight, 
         automatic tunneling mechanism should be standardized in the 
         IETF. 
       - Tunneling mechanisms can be used in 3GPP networks, and only 
         generic recommendations are given in this document. More 
         details can be found, for example, in [ISP-sa]. 
       - We 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. 
-----------

Rgds,
	 -Juha W.-