Paul Vixie wrote:
marcel@our.domaintje.com (Anne Marcel) writes:
There is no need to deaggregate the /16 that contain nullrouted /32's. This information is (in this case) already available from AS7777 as a multihop eBGP feed.
Nope. No part of ORBS is listed in AS7777. The block which inspired this thread is completely private to AS6461 and has to do with that network's AUG.
This sort of brings up an interesting point, though. Has anyone ever thought about adding a mechanism to BGP for advertising "anti-routes?" - routes that you can't, don't want to, or won't carry traffic for? In this case, such a capability could be used to redistribute the 194.178.0.0/16 route from UUNet, and add in a route for !194.178.232.55/32, all without messy deaggregation. Neighbors would have the option of using this as a type of automated blackhole avoidance. There are a few things that would stand in the way of adoption of something like this: first, each anti-route would require manual configuration, and that comes with its own set of problems. Another potential issue (this is purely theoretical, I'm not referring to any past, present, or future situation in particular) is that providers trying to blackhole a certain site for AUP violations may want to negatively impact reachability as much as possible, rather than purely keeping the offending traffic off their network. These folks wouldn't want to advertise anti-routes because the resulting blackhole avoidance would encourage others to take working alternate paths, which does less harm to the site in question. Still, this may be a beneficial, even if little-used, addition. Thoughts? Mark