Re: An idea: GxSE

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

> Every host knows at least one (and typically only one) address for itself,
> called the self-known address (SK address).  The SK address may or may not
> be globally routable, but must be globally unique.

I think that today there are distributed (multi-party) applications
that depend on an application being able to extract a globally routable 
IP address of the box (so that it can be passed to peers etc).
It would be good to run the idea of apps not knowing their GR addresses
passed folks with better application knowledge.

It the applications need to know the GR addresses but the host itself 
doesn't know them then it seems like you need a way to map from SK 
to GR addresses.

> The list of addresses (GR and SK) is conveyed to partner hosts by an IPv6
> extension header---the address-list extension.  This header is typically
> added by the site border router as the packet exits the site.  (It could

Having intermediate nodes change the length of the packet does cause some
issues with path MTU discovery. That's why encapsulation is normally used
(e.g. in mobile IP) to deal with this.

> Pseudo-header checksums and IPsec would I suppose be based on the SK address
> only (not the GR addresses).

It would be good to look at the effects of bit errors in the source GR address.
With no IPv6 header checksum and the GR address not being part of the
pseudo-header checksum means that it is unprotected. (Perhaps having a
checksum on the address-list extension can catch this.)

   Erik