BGP路由策略

AS-PATH

R4

ip as-path access-list 1 deny _200$
ip as-path access-list 1 permit .*
ip as-path access-list 2 permit _200_

route-map as-path1 permit 10
match as-path 2
set weight 100
!
route-map as-path1 permit 20

router bgp 400
bgp log-neighbor-changes
neighbor 192.168.34.3 remote-as 300
neighbor 192.168.34.3 route-map as-path1 in
neighbor 192.168.34.3 filter-list 1 in

community

在R1上为100.100.100.0的路由打上community标记100:1，前面的100是as号，后面的是自定义的路由器编号

R1#show run | sec ip acc  
R1#show run | sec acc   
access-list 1 permit 100.100.100.0
R1#sh run | sec route-map
neighbor 192.168.12.2 route-map comm out
route-map comm permit 10
match ip address 1
set community 6553601
route-map comm permit 20
R1#sh run | sec router bgp
router bgp 100
network 100.100.100.0 mask 255.255.255.0
neighbor 192.168.12.2 route-map comm out        #将community传递给R2
neighbor 192.168.12.2 send-community            #将community的更新发送过去，不发送的话R2看不到R1传过来路由100.100.100.-的community属性

在R2上查看关于100.100.100.0路由的community属性

R2
show ip bgp 100.100.100.0
    Community: 6553601          #我们发现看见的这个属性是我们看不懂的
ip bgp new-format       #使用新的格式显示community属性
show ip bgp 100.100.100.0
    Community: 100:1
router bgp 200
    neighbor 192.168.23.3 send-community

在R3上收到来自有关community 100:1的路由的时候改变他的权重为1001

R3#show run | sec ip com
ip community-list 1 permit 100:1
R3#show run | sec route-map
neighbor 192.168.23.2 route-map wei1 in
neighbor 192.168.34.4 route-map wei1 out
route-map wei1 permit 10
    match community 1
    set weight 1001
route-map wei1 permit 20
R3#sh run | sec router bgp
    router bgp 300
bgp log-neighbor-changes
    neighbor 192.168.23.2 remote-as 200
    neighbor 192.168.23.2 route-map wei1 in
    neighbor 192.168.34.4 remote-as 400
    neighbor 192.168.34.4 route-map wei1 out

在R2上设置策略让R4学不到关于100.100.100.0的路由

R2:
access-list 1 permit 100.100.100.0
route-map comm permit
match ip address 1
match community 100:1
set community local-AS additive
exit
route-map comm permit 20
router bgp 200
nei 192.168.23.3 route-map comm out
clear ip bgp * so

但是R3偏偏要告诉R4关于100.100.100.0的路由

R3：
access-list 2 permit 100.100.100.0
ip community-list 2 permit local-as 
route-map wei1 per 10
match ip add 2
set comm-list 2 delete