Request for Comments on a topological address block for N. Calif.

I see your point (and remember your earlier message), but that's not
a show stopper. To be in that situation, the small ISP has to have
bought ISP access connectivity from one or more ISPs in those geographically
disparate locations and not have them find out what's going on. If, say, (which is fictional (I hope 8-)) branched out to Miami,
and bought another Alternet ISP T-1 connection out there, they would
then be getting free transit between them. Presumably if both were
Alternet connections, you'd figure it out. If they bought Sprint access
in Miami, then they might fool both of you.

You could easily avoid this by adding a statement to your service contracts
for addresses allocated from these geographical block(s), which states that
there must be full disclosure to all involved upstream providers if the
company adds sites outside that area. If they fail to do so they would
then be defrauding you. This is a matter for you to work out with your
customers, so it's not really the address blocks' managements' issue.
You just have to keep a slight eye on people using the block space.

The basic problem isn't with geographical addressing per se. It is possible
for unscrupulous end users to set up things like this, with transit achived
surrepticiously (or an ISP claiming not to be to get the cheaper connect)
already, and I'm sure in some cases it is happening. Proper policy and
awareness is required to deal with it at whatever level it appears,
geographical addressing being one such level.



Let's take a clear example:

Let's use 39/8 as the Bay area prefix.
Suppose that gets 39.1.1/24 (just to be simple).
Suppose that they happen to connect to Fix-west but not to the SF NAP.

Suppose that gets 39.100.100/24 and connects to the NAP
and not to Fix-west.

Now, we can't summarize 39/8 into the backbones at either of the two
locations. Consider what happens if a backbone with only 39/8
delivers a packet to the NAP for What happens?

In fact, we have to move the AAB out. And we have to at least subsume
a biconnected (or triconnected?) subgraph of the backbones that
contains the interconnects.

The result is that we either summarize 39/8 to the backbones and
someone provides free transit between the NAP and Fix-West, or we get
no effective aggregation from 39/8.