The Inside-Out ISATAP Model

[Fred Templin <osprey67@yahoo.com>]

Hello,

I didn't get a chance to write a draft on this ahead of the deadline,
but I would like to propose a discussion topic for the design teams
at IETF 55. The topic proposes the use of ISATAP with globally-unique
interface identifiers, i.e., with the 'u/l' bit in the company code
set to "universal" and a globally unique IPv4 address.   

This feature enables the "Inside-Out ISATAP model", which I would also
like to propose as design team discussion material. For a diagrammatic
represenation of this model, see:

  http://www.geocities.com/osprey67/inside_out.ppt

In the traditional model, ISATAP operates "intra-site" as its name
implies. Nodes within an ISATAP site connect across the global Internet
to other sites via 6to4, native IPv6 routing, etc. But, when globally
unique IPv4 addresses are used, the model can be turned "inside-out".

In the inside-out model, ISATAP treats the global Internet as a
monolithic site with IPv6 clouds hanging off the edges. As in the
traditional model, ISATAP treats the IPv4 Internet as a link layer
for IPv6, thus the interface identifier is the natural place to
embed the link layer address. Moreover, this model allows all 64
bits of the routing prefix to be used for other purposes, e.g.
v6 routing.

Note that this model does NOT displace 6to4 and/or Teredo; instead,
all three mechanisms have important and complementary roles to play
in the global scheme. I would also like to suggest further discussion
along these lines in the design teams.

Fred Templin
osprey67@yahoo.com  

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