Re: Regionally aggregatable address space for multihoming

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

On Thu, 14 Jun 2001, Tony Li wrote:

> We decided a long time ago, for better or for worse, that we were not going
> to introduce a new routing architecture with IPv6.  We need a multihoming
> solution that at the very least halts the global routing table explosion.
> If we can't find one, then we have a bigger problem to be sure, but let's
> focus on trying to converge on something.

Let's see if we can agree on the problem:

The large number of multihomed network is responsible for growth of the
routing table, which we don't want because:

- it takes too much CPU power to process routing updates
- it takes too much memory to store the table
- it takes too much CPU power to look up routes when forwarding packets

Is stopping the routing table growth the best way to address these
problems? If so, the next step is to choose an approach, such as:

- not allowing or restricting multihoming the way it is done now
  This means we need alternatives, such as a good way to select the best
  address when a host has more than one and ways for higher layers
  to survive address changes.

- find a way to aggregate multihomed routes
  On what should we aggregate? Topology, geography?

- ???

I think the discussion so far shows that each approach has serious drawbacks,
but just waiting until the perfect solution comes along doesn't seem to work
either. So we need a way to select a best approach in lieu of a perfect one.
What do we value more? Effectiveness? Efficient operation? Simplicity?
Compatibility with current practices? How can we evaluate all of this if we
don't make assumptions about the future of the Internet?