ipv6 addressing - non-routable equivalents?

[Antonio Querubin]

On Thu, 5 Oct 2000, Jonathan Guthrie wrote:

> Yes, ::1 is a perfectly fine interface identifier, and I make use but it's
> not a GLOBAL interface identifier.  That is, interface identifiers with
> the global bit set are guaranteed to be unique on the Internet.  Perhaps
> my terminology is incorrect, but unless I can put multiple globally-unique
> interface identifiers on the same box, an awful lot of the magic IPv6
> promises simply isn't there.

I'm not sure what this really buys us.  So it's globally unique, ok.  We
already had that with IPv4 - though it wasn't 'guaranteed' to be unique.
But where's the 'magic'?

> The thing is, the Internet is NOT stupid with respect to routing.  In
> order to do anything more complicated than a single nonredundant
> connection, you have to have your equipment interact with the routing
> structure of the Internet.  One of the most common questions on the Zebra
> (a freeware routing protocol package) is "I've got two connections to the
> Internet at my house from different providers, can I use Zebra to help me
> use both of them at the same time?"  The answer, of course, is "no"
> because multihoming requires (in principle and usually in practice) that
> the entire Internet understand that routes through both providers are
> equally valid for the addresses in question.
> 
> Globally-unique interface identifiers gives us a chance to change that.
> 
> With globally-unique interface identifiers, it becomes possible for the
> software at the endpoints to determine that multiple routing options exist
> and to exercise their own control over what routes a packet take.  The
> rest of the Internet can simply take the attitude that the routing
> structure is a tree and pass the packets along, fat, dumb, and happy.

How so?  How does a globally unique IPv6 address provide this capability
that a globally unique IPv4 address does not?

> Of course, this requires more than the adoption of IPv6 to accomplish.  
> In particular, it requires the ability for the TCP and UDP implementations
> to recognize that packets sent from the same globally-unique interface
> identifier are from the same place even if the network numbers are
> different and it requires the routing software to routinely make routing
> decisions, at least in part, on the source address, and it may require
> other things I haven't thought of.  However, the point is that it doesn't
> work unless most interface identifiers are globally unique.

Uh, so one more time, how does the global uniqueness property of an IPv6
address provide this capability that a globally unique IPv4 address can't?

> I believe that many people will want to have multiple globally-unique
> interface identifiers on the same computer.  Is there a standard way of
> doing this?

The most common way hosting sites assign multiple addresses is to just
number them sequentially.  It's pretty simple and mindless and doesn't
require knowledge of the ethernet address on any NIC card.  Ie. it's KISS
compliant :)