1) Highest Local-Preference
2)Shortest AS-Path
3)Lowest Origin Type(IGP<BGP)
4)Lowest MED value(with the same next-hop AS)
5)E-BGP learned route over I-BGP learned
6)Lowest IGP cost to exit point(Hot-Potato)
7)Lowest router ID or BGP speaker
其实也就第一步是选择最高的,其余步骤都是选择最低的。