Subject: (ngtrans) SITT -05 Review Input

From: Jim Bound <[email-masked]>
Date: Wed, 31 Mar 1999 11:47:31 -0500

Bob, Tony, Alain, and Erik

I have spent a significant amount of time with SIIT and to review it for
implementation affect on the overall IPv6 state as a mechanism.  I have
only three issues other than all the nasty things that NAT causes in
general.

1.  The spec in the beginning talks about dual stacks and then V6 ONLY.
Some diagrams in the beginning stating the problem with examples and the
the path solution SIIT is taking would clear this up.  For example it is
important to identify if the Hosts "may" be v6/v4 capabale but are 
using SIIT because there are not enough addresses to assign the nodes
addresses in SIITs set of assumptions.  Which might be stated more
clearly.

2.  This is a biggie and affects NAT-PT to some degree too.

    My first impression is that the IPv4 Translated Address is not an
    optimal idea.  I would like to know why and stated in the spec why
    SIIT does not use an IPv4 Mapped Address for both cases.

    Using the IPv4 Translated address will cause IPv6 apps and ported 
    apps to now check IPv4 Mapped and IPv4 Translated.  This is not good
    we should not have multiple representations for IPv4 addresses.

    If the only reason is because RFC 2373 says IPv4 Mapped cannot 
    represent an IPv6 Node, we should fix RFC 2373 not use IPv4 
    Translated addresses.

3.  In the spec first it says ESP may work then in the Security
Considerations it says it will work with Transport mode preferred.
Can the spec please tighten the wording up here and state if it does or
not.

One NIT:  RFC 2133 REF should be changed to RFC 2553.

/jim