> Yeah, definately. But most backbones seem to have "customer routes" as
> an option, and if I trust them enough to get those routes correct then
> I will hopefully not have to bother with extreme amounts of filtering.
> It's pretty easy to enforce "no transit" at the packet filtering level
> -- only packets destined for my nets will be allowed in. Is there some
> other aspect of filtering I'm forgetting about? We have a dedicated
> and backup network engineer at any rate. The border router would be a
> cisco 7200 or 7500 series with 128Mb.
Is this really how people enforce "no transit"? I have been told that packet
filtering is quite cpu expensive. I would think that packet filtering on a
router that is probably already overburdened is not an attractive solution.
I'm not sure if this is how people enforce it; you're correct that it's
pretty expensive to do it this way.
We run a periodic script that sends 8-10 pings for various destinations,
including non-existent ones, into exchange-point neighbors to see where
the packets go.
If packets for nowhere IPs come back at you, they're defaulting into you...