From Wendell Odom’s CCNP ROUTE 642-902 Official Certification Guide:
Hint:
* Up to AS Path higher values win
* After AS Path lower values win
N WLLA OMNI
N = next hop reachability
W = weight
L = local preference
L = locally injected in the BGP process
A = AS path length
O = origin (igp < egp < incomplete)
M = MED
N = neighbor type (ebgp < ibgp)
I = IGP metric to BGP next-hop
And my own contribution to this list:
ORCA
O = Oldest route wins
R = Router-ID, lowest wins
C = Cluster list, shortest wins
A = Address of the BGP neighbor, lowest wins
Of course there are several options that can affect the order of the above process.
For details check on Cisco: BGP Best Path Selection Algorithm
