Re: Draft: PI addressing derived from AS numbers

[Erik Nordmark <Erik.Nordmark@sun.com>]

> Why would we want to have two sets of addresses in any part of the
> communication path? The identifiers can simply be replaced by locators
> (and vice versa) between the TCP and IP layers. This could also be done
> by external boxes if those aren't bothered by the state that must be
> kept.

I think that conceptually they are all present in each packet.
Some form of end-to-end "header compression" can presumably remove the need
for the identifiers in every packet, but presumbly this is a function
of the state at the endpoints.

It would presumably be easier to maintain the compression state in
the transport protocols (due to fate sharing etc) than in a separate
entity, whether it is below transport in the endpoints or in a separate box.

> A solution where the identifier is present in each packet may be simpler
> to implement, but only if there is no additional complexity for
> authenticating the identifier, which seems unlikely.

Good point.

Perhaps providing a reasonably strong binding between the identifiers 
and locators in some initial packet(s), and having subsequent packets only
contain the locators (at least until a locator changes) might be the
right model.

   Erik