Ripe 181

 * You raise an interesting point iabout counter intuitive behaviour
 * of CIDR though: 
 * 
 * AS1 is connected to AS2 and AS3
 * 
 * AS1 policy says to prefer all routes learned from AS2 over anything
 * learned from AS3
 * 
 * AS3 announces a more specific route inside a route announced by AS2.
 * 
 * According to CIDR rules the more specific route takes precedence.
 * My gut says that some properties of BGP-4/IDRIP may actually depend on this.
 * 
 * Those specifying the routing policy would probably want less specific route 
 * to take precedence because they do not trust AS3 as much.

If you would use the RR properly then also the more specifics would be
included in the network list generated for routes from AS2. If this is
not the case, then it would not accept the more specific from either
AS2 or AS3 (which is fine, it will use the less specific with better
preference from AS2), or when it is present, it will accept it
from AS2 over AS3 (which is als fine). Ie the more specific must be in
the RR to make this work. If one only filters on AS paths or origins,
this would indeed give the counter intuitive result. 

Ergo, always filter using netlists if you are not sure what your
neighbours are doing....

-Marten



-------- Logged at  Thu Oct 13 19:49:31 MET 1994  ---------