Re: The state of IPv6 multihoming development

[Iljitsch van Beijnum <iljitsch@muada.com>]

On Tue, 22 Oct 2002, Michael H. Lambert wrote:

[Listing several addresses for a server and the application trying them
all in order to achieve a low degree of multihoming functionality]

> As a (perhaps) extreme case in this scenario, consider the situation of two
> sites which can communicate over either the commodity Internet or a
> Research and Education network (most likely high bandwidth and/or low
> latency).  If viewed only from a reachability standpoint, either path would
> work, but there are applications which demand the latter.  Simply returning
> a list of IP addresses to be tried in order is probably not sufficient in
> this case (in fact, both of these sites might have addresses, which,
> because of conditions of use on the network [ie, routing policy], cannot be
> reached from an arbitrary third site).

This assumes a network/server/service has several addresses with each
address tied to a certain service quality. Is this the best way to go?
Obviously, at some point somewhere, the decision has to be made to
select the higher quality path. What would be the best place to do this?

The simple solution is to use the same addresses over both links and
simply route all traffic over the higher quality link.

A more advanced solution would be that the application or some kind of
classifyin device sets a diffserv code point that then makes sure the
appropriate path is chosen.

The solution where there are different addresses with "hidden meanings"
doesn't appeal much to me.

> What is the validity of this statement:  All PA addresses (at least at RIR
> allocation boundaries) MUST appear in the DFZ.

In the good old days many people requested routable (but not PA) space
with no intention to connect to the net. Having unique space is helpful
when interconnecting privately with others. There is even an RFC "RFC
1597 space considered harmful" or words to the same effect.

Also, what are you going to do with people that break this rule?
Disconnect them from the net?  :-)

Iljitsch