BGP属性控制及选路原则，结合路由策略

一、配置路由器的接口及环回的IP地址，注意在配置r1,r2,r3的环回接口时要满足要求10

二、配置AS 123的IGP，使用OSPF

三、配置BGP，注意要满足要求9

四、前三个步骤不是本次实验的重点，故不再赘述。根据要求看实验配置

要求1：
[r4]ip ip-prefix PV permit 192.168.10.0 24 
[r4]route-policy PV permit node 10
[r4-route-policy]if-match ip-prefix PV
[r4-route-policy]apply preferred-value 100
[r4-route-policy]q
[r4]route-policy PV permit node 20

[r4]bgp 400
[r4-bgp]peer 24.0.0.2 route-policy PV import 
--精细化修改---只能r4配置（入方向），因为修改的是PV属性，该属性仅具有本地意义，不会传递----默认0，越大越优

要求2：
[r4]ip ip-prefix AS permit 192.168.11.0 24
[r4]route-policy AS permit node 10    
[r4-route-policy]if-match ip-prefix AS
[r4-route-policy]apply as-path 123 123 additive 
[r4-route-policy]q
[r4]route-policy AS permit node 20
[r4-route-policy]q
[r4]bgp 400
[r4-bgp]peer 24.0.0.2 route-policy AS import 

AS-Path 默认值0，越短越优。要想走r3，就得让r2的AS_Path数值长一点

MED数值越小越优。在EBGP对等体的入方向或出方向修改

要求3：
[r4]ip ip-prefix MED permit 192.168.12.0 24    
[r4]route-policy MED permit node 10
[r4-route-policy]if-match ip-prefix MED
[r4-route-policy]apply cost 20
[r4-route-policy]q
[r4]route-policy MED permit node 20
[r4-route-policy]q
[r4]bgp 400
[r4-bgp]peer 24.0.0.2 route-policy MED import 

要想通过r3，就得让r2的med改大/或者将r3的med改小

 

 要求4：
精细化修改，r2/r3的出方向或r1的入方向。这里我们选择r1的入方向
[r1]ip ip-prefix LP permit 192.168.1.0 24    
[r1]route-policy LP permit node 10
[r1-route-policy]if-match ip-prefix LP
[r1-route-policy]apply local-preference 200
[r1-route-policy]q
[r1]route-policy LP permit node 20
[r1]bgp 123
[r1-bgp]peer 2.2.2.2 route-policy LP  import 

要求5：
精细化修改，r2/r3的出方向或r1的入方向。这里我们选择r1的入方向
[r1]ip ip-prefix LP2 permit 192.168.2.0 24
[r1]route-policy LP2 permit node 10
[r1-route-policy]if-match ip-prefix LP2
[r1-route-policy]apply local-preference 300
[r1-route-policy]q
[r1]route-policy LP2 permit node 20
[r1-route-policy]q
[r1]bgp 123
[r1-bgp]peer 3.3.3.3 route-policy LP2 import 

 

要求7：

[r1]ip as-path-filter 1 pe    
[r1]ip as-path-filter 1 permit .*
[r1]bgp 123
[r1-bgp]peer 15.0.0.5 as-path-filter 1 export 

要求8：
在此之前，要开启社团属性传播功能
[r4]bgp 400
[r4-bgp]peer 24.0.0.2 advertise-community
[r4-bgp]peer 34.0.0.3 advertise-community
[r4-bgp]q
[r4]route-policy com permit node 10
[r4-route-policy]apply community 400:100   
[r4-route-policy]q
[r4]bgp 400    
[r4-bgp]network 192.168.3.0 route-policy com --宣告时打上标记
[r4-bgp]display bgp routing-table 192.168.3.0 -- 查看是否打上标记    

[r2-bgp]peer 1.1.1.1 advertise-community

[r3-bgp]peer 1.1.1.1 advertise-community

[r1]bgp 123
[r1-bgp]peer 15.0.0.5 advertise-community
[r1-bgp]display bgp routing-table 192.168.3.0

[r1-bgp]q
[r1]ip  community-filter  1 permit 400:100   ---社团属性过滤器
[r1]route-policy aa deny node 10
[r1-route-policy]if-match community-filter 1
[r1-route-policy]q
[r1]route-policy aa permit node 20
[r1-route-policy]q
[r1]bgp 123
[r1-bgp]peer 15.0.0.5 route-policy aa export 

 通过display bgp routing-table命令，可以看到r5上没有192.168.3.0/24的路由信息