Re: How does one make not playing nice with each other scale?

[Mark Mentovai <mark-list () mentovai com>]

Greg A. Woods wrote:
> Well if these "anti-routes" really do have to be manually configured
> then it's still not really scalable.  If their advertisement in the
> routing protocols could somehow be automated and hard to disable then
> maybe they'd obviously be of some use.

Perhaps "redistribute null" or "redistribute blackhole" (or insert your
vendor's equivalent here) could be used to redistribute static null routes
as anti-routes.  Provided that the violators are being filtered by null
routes as opposed to access lists, this could be made to work.

> Clearly a "hidden" null route (or even a real packet filter dropping
> packets for some subnet) does violate the advertisement of the larger
> aggregate route, and from what I've seen there are lots of people who
> are "surprised" (to say the least) to learn that they can't get packets
> to these null-routed networks via an encompassing route advertised by
> one of their upstreams.  Packets is packets boyz and goilz, and if
> you're advertising transit across your borders but not actually
> providing it then you're most definitely not a very good network
> neighbour.  I.e. policy based routing should be either outlawed for
> transit providers, or required to be clearly advertised in such a way
> that network peers can automate their routing decisions based on
> real-time policy changes within their peer's networks (but perhaps
> that's another non-operational discussion!  :-).

Trying to keep the politics aside as much as possible, it's conceivable that
"not advertising anti-routes for traffic you plan to drop while continuing
to advertise routes for the parent network" could in the future come to be
seen as bad as "blackholing by advertising (potentially more specific)
routes you aren't entitled to advertise" is today.  In other words, if an
accepted anti-route capability existed, there would no longer be any excuse
for effective (as opposed to explicit) blackholing.

Mark