> 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.
Let me take an example, route 1.1.1.0/24 is pointed to interface A, while route 1.1.0.0/16 is pointed to interface B. if most routes are pointed to interface A, in your theory, those routes with interface A as exit interface, including route 1.1.1.0/24, will be replaced by 0.0.0.0/0 in the FIB. This will cause a wrong route for packets to 1.1.1.0/24. Is my understanding correct? Xiaohu XU > 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 -- 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
