From a technical standpoint, can't you multihome and use PA addresses for external comms and also create a numbering solution for provider independent internal numbering for critical systems by using RFC 4193 Unique Local IPv6 Unicast Addresses http://www.ietf.org/rfc/rfc4193.txt ? I thought this RFC was created to handle a provider independent internal numbering solution within a single routing domain (AKA North American Air Traffic Control) or other large critical operations enterprise.

>From RFC 4193:
 Local IPv6 unicast addresses have the following characteristics:

      - Globally unique prefix (with high probability of uniqueness).

      - Well-known prefix to allow for easy filtering at site
        boundaries.

      - Allow sites to be combined or privately interconnected without
        creating any address conflicts or requiring renumbering of
        interfaces that use these prefixes.

      - Internet Service Provider independent and can be used for
        communications inside of a site without having any permanent or
        intermittent Internet connectivity.

      - If accidentally leaked outside of a site via routing or DNS,
        there is no conflict with any other addresses.

      - In practice, applications may treat these addresses like global
        scoped addresses.

4.2.  Renumbering and Site Merging

   The use of Local IPv6 addresses in a site results in making
   communication that uses these addresses independent of renumbering a
   site's provider-based global addresses.

   When merging multiple sites, the addresses created with these
   prefixes are unlikely to need to be renumbered because all of the
   addresses have a high probability of being unique.  Routes for each
   specific prefix would have to be configured to allow routing to work
   correctly between the formerly separate sites.`

Does anyone have a technical analysis of how to multihome with RFC 4193 addresses as a PI address space? Can we combine this with multihomed global addresses to avoid a NAT-like trap that hurts the E2E model? Perhaps we need a MOONv6 experiment designed to test this as a PI space option? David Green US Army CERDEC Site Manager SRI International Office: (732) 532-6715 Mobile: (732) 693-6500