RE: The state of IPv6 multihoming development

[Greg Maxwell <gmaxwell@martin.fl.us>]

On Wed, 23 Oct 2002, Randy Bush wrote:

> > I've still yet to see an idea here that provided complete multihoming
> > (i.e. ones that won't get filtered to uselessness)
>
> as i am not aware of anyone filtering v6 announcements at the moment
> (well, other than maybe at /48 or something), perhaps this wg should
> work on solutions to the routing problems presented and assume that,
> if reasonable aggregation is one of those goals and is met, that the
> isps will act rationally.

Lets say that everyone who mutihomes will take their provider based
address and announce it to other providers.. This would work..
But it would also explode the DFZ..

Okay, so people could filter the smaller routes... effectively
de-multihoming the multihomer.. so filtering is not a reasonable solution
to multihoming caused DFZ inflation.

So, here is the point of the problem:

Do we care about inflating the DFZ?

  Keep in mind that DFZ inflation is more costly in v6 due to the larger
  amount of data involved and the expected growth of multihomed networks..
  and that it's price carried by everyone, even people without business
  relationships with the multihomers

If we don't care (which I think would be an example of extremely poor
foresight..) then multihomers should just announce more-specifics of
their other providers address blocks and act just like it is in the v4
world.  Problem solved.

If we do care about preserving aggregation (one of the stated goals of
IPv6), then we can NOT permit *any* multihoming aggregation busting and
multihoming must be provided either by transport layer enhancements (my
favor, see archives) or via tunnel hacks.

I got tired of discussing the matter because of the group's unwillingness
to seriously consider transport layer modifications (wah wah outside of
the scope blah.. I thought my argument for prefix flowthrough and SCTP
was compelling.. No DFZ busting, the only catch was that legacy apps
wouldn't be multihomed: a good reason to upgrade them).. If you simply can
not do anything but break aggregation then fine, stop waffling and
declare it already. The problem isn't just going to go away.

The only thing worse then making a bad decision is wasting a lot of time
making a bad decision.