Friday, June 24, 2016

BGP Bestpath Selection - Weight

BGP Bestpath Selection

1. Ignore invalid paths (no valid next-hop, not synchronized, looped).
2. Prefer path with the highest locally assigned weight value.
3. Prefer path with the highest Local Preference attribute value.
4. Prefer locally originated prefixes (originated via the network, aggregate-address, or redistribution commands).
5. Prefer path with the shortest AS_PATH attribute length.
6. Prefer path with the lowest Origin Type (value for the Origin code), where IGP < EGP < Incomplete.
7. Prefer path with the lowest MED attribute value (provided that the first AS in the list is the same).
8. Prefer external BGP paths over internal BGP paths.
9. Prefer path with the smallest IGP metric to reach the NEXT_HOP IP address.
10. Prefer path originated from the router with the lowest BGP Router ID




access-list 10 permit 44.44.44.0 0.0.0.255

route-map SET-WEIGHT permit 10
 match ip address 10
 set weight 100

R1#
router bgp 100
   no synchronization
   bgp log-neighbor-changes
   network 1.1.1.0 mask 255.255.255.0
   neighbor 12.1.1.2 remote-as 100
   neighbor 13.1.1.3 remote-as 100
   neighbor 13.1.1.3 route-map SET-WEIGHT in







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