2011/7/18，知识点

1、BGP选路原则：（红色为可以人为修改）

Prefer highest weight (local to router).
Prefer highest local preference (global within AS).
Prefer route originated by the local router (next hop = 0.0.0.0).
Prefer shortest AS path.
Prefer lowest origin code (IGP < EGP < incomplete).
Prefer lowest MED (exchanged between autonomous systems).
Prefer EBGP path over IBGP path.
Prefer the path through the closest IGP neighbor.
Prefer oldest route for EBGP paths.
Prefer the path with the lowest neighbor BGP router ID.
Prefer the path with the lowest neighbor IP address.

2、BGP不将自己的次优路径更新出去。