BGP_属性

实验拓扑：

  一、weight（cisco私有）

1、传播范围：仅本路由器。

2、属性默认值：本地32768，学习到为0

3、优先级（越大越好），属性的变化只会影响本身。

 方法1：R1配置：neighbor 2.2.2.2 weight 10

 方法2：R1配置：

access-list 1 permit 3.3.3.0

route-map weight permit 10

　　match ip address 1

　　set weight 10

route-map weight permit 20

router bgp 1

　　neighbor 2.2.2.2 route-map weight in

 

 二、Local Preference

1、传播范围：一个AS内部

2、属性默认值：100

3、优先级（越大越好）

定义：Local preference is used to advertise to IBGP neighbors about how to leave their AS。local preference属性用来告诉他们的IBGP邻居如何离开他们的AS。

 方法1：R2上配置：bgp default local-preference 120

 方法2：R2上配置：

 access-list 1 permit 3.3.3.0

route-map loc permit 10

　　match ip address 1

　　set local-preference 120

route-map loc permit 20

router bgp 1

　　neighbor 1.1.1.1 route-map loc out

 

三、AS-Path

  R4配置：

 access-list 1 permit 3.3.3.0

 route-map as permit 10

 　　match ip address 1

 　　set as-path prepend 6 6 6 

 route-map as permit 20

 router bgp 1

 　　neighbor 34.1.1.3 route-map as in

 或者

R3配置：

access-list 1 permit 3.3.3.0

route-map as permit 10

　　match ip address 1

　　set as-path prepend 6 6 6 

route-map as permit 20

router bgp 1

　　neighbor 34.1.1.4 route-map as out

 

四、MED

1、传播范围：1个AS内部

2、属性默认值：0

3、优先级：小好

MED is used to advertise to EBGP neighbors how to exit their AS to reach networks owned by this AS。

R2配置：

access-list 1 permit 1.1.1.0

route-map med permit 10

　　match ip address 1

　　set metric 10

route-map med permit 20

router bgp 1

　　neighbor 23.1.1.3 route-map med out