On Tue, Aug 18, 2009 at 09:37:22AM +0200, Ivan Pepelnjak wrote: > > Anybody have a handy route-map that will deny anything with a > > as-path longer than say 15-20? ;-) > > http://wiki.nil.com/Filter_excessively_prepended_BGP_paths
It will still be a while before we see unbroken 4byte AS behavior (that whole 'fix the teardown on a anyone sneezing' problem). But like with stale bogon filters, I expect folks inclined to use this to drop it in and forget about it. So it would be wise to adjust the recommended filter to anticipate a 2byteAS view allowing multiple instances of AS-TRANS; there's likely a more elegant approach, but the quick step of explicitly allowing _(23465_)+ before you deny _([0-9]+)_\1_\1_\1_\1_ Cheers, Joe -- RSUC / GweepNet / Spunk / FnB / Usenix / SAGE