RE: The state of IPv6 multihoming development

["Craig A. Huegen" <chuegen@cisco.com>]

On Tue, 22 Oct 2002, J. Noel Chiappa wrote:

> context." There's probably no single mechanism which is "the" answer to
> multi-homing; you probably need several, each with its own optimal
> applicability domain.

So why not support PI for a limited subset of multihomers that have vast
networks while supporting multi-PA for the small networks that have a
minimal number of segments?

> How much extra code is it, really? It can't be as much code as IPv6 Mobility,
> or Authrntication, each of which is already mandated.

The issue isn't code, IMO -- it's adoption.  How long will it take to get
global implementation of a new multihoming capability into IPv6?  I think
it's time to take advantage of the surge in popularity of IPv6 and get it
into enterprise networks, before the steam is lost.

> In any event, if you think it's too much extra complexity, use IPv6 Mobility
> instead. That way you'll also get connection failover if you have to switch
> addresses dynamically because one of your incoming links went down.

End-user operators want SIMPLICITY, just like the provider operators like
simplicity.  Mobile IP / IPv6 mobility is certainly not simplicity.

>     > the real question is whether multihoming in IPv6 will be good enough to
>     > get people who multihome "for free" to move to v6.
>
> Hmm. If the current multi-homing "solution" (where the load of supporting
> multi-homing is borne entirely by the routing) "works" (and I don't think it
> does, but let me play advocatus diaboli here for a second), why not adopt it
> "as is" for IPv6?

You're looking at it in black-and-white (works vs. not works) when the
real issue is gray -- a matter of scale, both near-term and long-term.

It's pretty obvious to me that we need a simple way to multi-home such
that enterprises can treat an IPv6 Internet as business-critical, that
gives the routing infrastructure the ability to select alternate paths
based on policy (whether manual, infrastructure characteristics, etc.)

It's pretty obvious to me that multi-PA does not work for an end-user that
has more than several hundred segments throughout its infrastructure, due
to the configuration and maintenance load, the inability to failover or
automatically deprecate addressing when delivery of traffic to a
particular multi-PA prefix dies, and the inability of the enterprise
network operator to implement network-based policy for path preference.

It's pretty obvious to me that, for the time being, PI addressing could be
leveraged to support those organizations for which multi-PA is a
significant trouble, and therefore encourage those organizations to adopt
IPv6 instead of ignore it.  These organizations can migrate to the
Ultimate Multihoming Solution (UMS) as soon as feasible.

It's pretty obvious to me that aggregation is a Good Thing, and therefore,
anything that would be helpful for PI aggregation in the future may be a
good idea.

I'm offering that existing PI be adopted "as is" for the time being for
adoption purposes, coupled with a promise/demand that it be retired as
soon as the better mousetrap comes along.

/cah

---
Craig A. Huegen, Chief Network Architect      C i s c o  S y s t e m s
IT Transport, Network Technology & Design           ||        ||
Cisco Systems, Inc., 400 East Tasman Drive          ||        ||
San Jose, CA  95134, (408) 526-8104                ||||      ||||
email: chuegen@cisco.com       CCIE #2100      ..:||||||:..:||||||:..