BGP is a path vector routing protocol. It actually uses hop count " Autonomous systems" for path selection provided the next hop must be reachable.
BGP uses these attributes in this order for path selection, until it finds an attribute that is not a tie and different values.
These values can also be manipulated for path selection by you for traffic engineering
1.Prefer the path with the highest WEIGHT. (this is a proprietary attribute and only local to the router) default is
2.Prefer the path with the highest Local pref. (default 100)
3. Prefer the path that was locally originated
4. Shortest AS-path (this normally breaks the tie , as the top 3 has default values.
5.Prefer the path with the lowest origin type. (igp lower than Exterior Gateway Protocol (EGP), and EGP is lower than incomplete)
6.Prefer the path with the lowest MED
7.Prefer eBGP over iBGP paths
8.Prefer the path with the lowest IGP metric to the BGP next hop
9.Determine if multiple paths require installation in the routing table for BGP multipath (multipath is for load balancing)
10.When both paths are external, prefer the path that was received first (the oldest one)
11.Prefer the route that comes from the BGP router with the lowest router ID
It normally stops here if all other attributes are the same, but if for some reason not then:
12.If the originator or router ID is the same for multiple paths, prefer the path with the minimum cluster list length
13.Prefer the path that comes from the lowest neighbor address
