NAT-PT Applicabilty for 3GPP

[Suresh Satapati <satapati@cisco.com>]

Randy,

The scenario in question is the one mentioned in the 3GPP Scenarios
document. Refer to RFC 3574 Section 4.2, subsection 1.

As per the analysis/solution for this specific IMS scenario, please refer
to Section 4.1 of "Analysis on IPv6 Transition in 3GPP Networks"
http://www.ietf.org/internet-drafts/draft-ietf-v6ops-3gpp-analysis-07.txt:

<snip>
    Figure 1 shows a possible configuration scenario where the SIP ALG
    is separated from the CSCFs. The translator can either be set up in
    a single device with both SIP translation and media translation, or
    those functionalities can be divided to two different entities with
    an interface in between. We call the combined network element on
    the edge of the IPv6-only IMS an "Interworking Unit" in this
    document. A SIP-specific translation mechanism, which could e.g.
    re-use limited subsets of NAT-PT [RFC2766], needs to be specified.
    The problems related to NAT-PT are discussed in appendix A.

</snip>

In the above, though a SIP-specific translation mechanism is being
recommended, I do not see how the recommended solution will be
fundamentally different from NAT-PT. In this sense, the applicability
of NAT-PT is still valid.

Thanks
--
Suresh