3gpp-analysis-04: SIP/SDP transition

[Pekka Savola <pekkas@netcore.fi>]

Hi,

The text in section 4.2 on IMS scenarios describes SIP/SDP transition
scenarios.  At least based on Karim El-Malki et al.'s work, it is not
apparent that ALG should/has to change the SIP messages and SDP payload.  
I thought the "architectural" approach would have been been different,
i.e., in principle, make the IPv6-only IMS aware of the payload
translation, a la RSIP.  In any case, the SIP/SDP transition scenarios
need to be fleshed out a bit more.

=====
    SIP and SDP transition has to be made in an SIP/SDP Application
    Level Gateway. The ALG has to change the IP addresses transported
    in the SIP messages and the SDP payload of those messages to the
    appropriate version. In addition, there has to be interoperability
    for DNS queries; see section 4.1 for details.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings