Hi Folks, Iljitsch's current geoagg plan didn't pan out either, but it gave me an idea. Your comments are requested.
Suppose when we calculate the FIB from the RIB, we do the following optimization: 1. Determine which exit has the most routes pointing at it. 2. Add 0.0.0.0/0 pointing at that exit. 3. Mark the routes that point in that direction and aren't cutouts of a larger route as non-FIB. These won't be imported into the FIB. 4. Mark the rest of the routes for import into the FIB. 5. Look at the routes in the two /1's inside that /0, considering both the marked and unmarked ones. Do any of the /1's have the majority of the routes pointing towards a different exit than the /0? If so, add the /1 and change the markings on the subroutes accordingly. 6. If both /1's point a different direction than the /0, remove the /0. 7. Inside each /1, repeat steps 5 and 6 using /2's. 8. Repeat for /3, /4, ... /8 In theory, this should result in identical routing for all routes which are actually in the RIB while cutting the FIB size significantly. In the worst case you should see FIB reduction equal to 1/(number of BGP interfaces) of the RIB table. Near the edge you should normally get much more. The obvious weakness of this approach is that packets which would ordinarily generate a host-unreachable will instead tend to fall into an odd routing loop until the TTL expires. Other than that, would it work? Comments? Criticism? Further thoughts? It is Monday morning and I haven't thoroughly vetted the idea so it may be DOA. Regards, Bill Herrin -- William D. Herrin ................ [EMAIL PROTECTED] [EMAIL PROTECTED] 3005 Crane Dr. ...................... Web: <http://bill.herrin.us/> Falls Church, VA 22042-3004 -- to unsubscribe send a message to [EMAIL PROTECTED] with the word 'unsubscribe' in a single line as the message text body. archive: <http://psg.com/lists/rrg/> & ftp://psg.com/pub/lists/rrg
