BGP路由策略

1.配置IP

R1

system name R1
[R1]int g0/0/0
[R1-GigabitEthernet0/0/0]ip ad 12.0.0.1 24
[R1-GigabitEthernet0/0/0]int g0/0/1
[R1-GigabitEthernet0/0/1]ip ad 13.0.0.1 24
[R1-GigabitEthernet0/0/1]int g0/0/2
[R1-GigabitEthernet0/0/2]ip ad 15.0.0.1 24
[R1-GigabitEthernet0/0/2]int l0
[R1-LoopBack0]ip ad 1.1.1.1 32
[R1-LoopBack0]int l1
[R1-LoopBack1]ip ad 192.168.100.1 24
[R1-LoopBack1]ospf network-type broadcast 

R2

system name R2
[R2]int g0/0/0
[R2-GigabitEthernet0/0/0]ip ad 24.0.0.2 24
[R2-GigabitEthernet0/0/0]int g0/0/1
[R2-GigabitEthernet0/0/1]ip ad 12.0.0.2 24
[R2-GigabitEthernet0/0/1]int l0
[R2-LoopBack0]ip ad 2.2.2.2 32
[R2-LoopBack0]int l1
[R2-LoopBack1]ip ad 192.168.20.1 24
[R2-LoopBack1]ospf network-type  broadcast 

R3 

system  name R3

[R3]int g0/0/0
[R3-GigabitEthernet0/0/0]ip ad 34.0.0.3 24
[R3-GigabitEthernet0/0/0]int g0/0/1
[R3-GigabitEthernet0/0/1]ip ad 13.0.0.3 24
[R3-GigabitEthernet0/0/1]int l0
[R3-LoopBack0]ip ad 3.3.3.3 32
[R3-LoopBack0]int l1
[R3-LoopBack1]ip ad 192.168.30.1 24
[R3-LoopBack1]ospf network-type  broadcast 

R4

system name R4

[R4]int g0/0/0
[R4-GigabitEthernet0/0/0]ip ad 24.0.0.4 24
[R4-GigabitEthernet0/0/0]int g0/0/1
[R4-GigabitEthernet0/0/0]ip ad 34.0.0.4 24
[R4-GigabitEthernet0/0/0]int l0
[R4-LoopBack0]ip ad 192.168.1.1 24
[R4-LoopBack0]int l1
[R4-LoopBack1]ip ad 192.168.2.1 24
[R4-LoopBack1]int l2
[R4-LoopBack2]ip ad 192.168.3.1 24

R5

systen name R5

[R5]int g0/0/0
[R5-GigabitEthernet0/0/0]ip ad 15.0.0.5 24
[R5-GigabitEthernet0/0/0]int l0
[R5-LoopBack0]ip ad 192.168.10.1 24
[R5-LoopBack0]int l1
[R5-LoopBack1]ip ad 192.168.11.1 24
[R5-LoopBack1]int l2
[R5-LoopBack2]ip ad 192.168.12.1 24

2.开启OSPF

R1

[R1]ospf 1 router-id 1.1.1.1
[R1-ospf-1]area 0
[R1-ospf-1-area-0.0.0.0]network 1.1.1.1 0.0.0.0
[R1-ospf-1-area-0.0.0.0]network 12.0.0.1 0.0.0.0
[R1-ospf-1-area-0.0.0.0]network 13.0.0.1 0.0.0.0
[R1-ospf-1-area-0.0.0.0]network  192.168.100.1 0.0.0.0

R2 

[R2]ospf 1 router-id 2.2.2.2
[R2-ospf-1]area 0
[R2-ospf-1-area-0.0.0.0]network 2.2.2.2 0.0.0.0
[R2-ospf-1-area-0.0.0.0]network 12.0.0.2 0.0.0.0 
[R2-ospf-1-area-0.0.0.0]network 192.168.20.1 0.0.0.0

R3

[R3]ospf 1 router-id 3.3.3.3
[R3-ospf-1]area 0
[R3-ospf-1-area-0.0.0.0]network 13.0.0.3 0.0.0.0 
[R3-ospf-1-area-0.0.0.0]network 3.3.3.3 0.0.0.0
[R3-ospf-1-area-0.0.0.0]network 192.168.30.1 0.0.0.0

3.配置BGP

R1

[R1]bgp 123
[R1-bgp]router-id 1.1.1.1
[R1-bgp]peer 15.0.0.5 as-number 500
[R1-bgp]peer 2.2.2.2 as-number 123    
[R1-bgp]peer 2.2.2.2 connect-interface l0
[R1-bgp]peer 2.2.2.2 next-hop-local
[R1-bgp]peer 3.3.3.3 as-number 123    
[R1-bgp]peer 3.3.3.3 connect-interface l0
[R1-bgp]peer 3.3.3.3 next-hop-local

R2

[R2]bgp 123
[R2-bgp]router-id 2.2.2.2
[R2-bgp]peer 24.0.0.4 as-number 400
[R2-bgp]peer 1.1.1.1 as-number 123
[R2-bgp]peer 1.1.1.1 connect-interface l0
[R2-bgp]peer 1.1.1.1 next-hop-local

R3
[R3]bgp 123
[R3-bgp]router-id 3.3.3.3
[R3-bgp]peer 34.0.0.4 as-number 400
[R3-bgp]peer 1.1.1.1 as-number 123
[R3-bgp]peer 1.1.1.1 connect-interface l0
[R3-bgp]peer 1.1.1.1 next-hop-local

 R4 

[R4]bgp 400

[R4-bgp]router-id 4.4.4.4

[R4-bgp]peer 24.0.0.2 as-number 123

[R4-bgp]peer 34.0.0.3 as-number 123

R5

[R5]bgp 500

[R5-bgp]router-id 5.5.5.5

[R5-bgp]peer 15.0.0.1 as-number 123

4.宣告BGP路由

R1

[R1]bgp 123

[R1-bgp]net 192.168.20.0 24

[R1-bgp]net 192.168.30.0 24

[R1-bgp]net 192.168.100.0 24

R2

[R2]bgp 123

[R2-bgp]net 192.168.20.0 24

[R2-bgp]net 192.168.30.0 24

[R2-bgp]net 192.168.100.0 24

R3

[R3]bgp 123

[R3-bgp]net 192.168.20.0 24

[R3-bgp]net 192.168.30.0 24

[R3-bgp]net 192.168.100.0 24

R4

[R4]bgp 400

[R4-bgp]net 192.168.1.0 24

[R4-bgp]net 192.168.2.0 24

[R4-bgp]net 192.168.3.0 24

R5

[R5]bgp 500

[R5-bgp]net 192.168.10.0 24

[R5-bgp]net 192.168.11.0 24

[R5-bgp]net 192.168.12.0 24

要求 

1.使用Preval策略，确保R4通过R2到达192.168.10.0/24

[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-route-policy]q
[R4]bgp 400
[R4-bgp]peer 24.0.0.2 route-policy PV import

2、使用AS Path策略，确保R4通过R3到达192.168.11.0/24

[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 overwrite
[R4-route-policy]q
[R4]bgp 400
[R4-bgp]peer 34.0.0.3 route-policy PV import

3、配置MED策略，确保R4通过R3到达192.168.12.0/24 

R2

[R2]ip ip-prefix MED permit 192.168.12.0 24
[R2]route-policy MED permit node 10
[R2-route-policy]if-match ip-prefix MED
[R2-route-policy]apply cost 200
[R2-route-policy]q
[R2]route-policy MED permit node 20
[R2]bgp 123
[R2-bgp]peer 24.0.0.4 route-policy MED export

R3 

[R3]ip ip-prefix MED permit 192.168.12.0 24
[R3]route-policy MED permit node 10
[R3-route-policy]if-match ip-prefix MED
[R3-route-policy]apply cost 200
[R3-route-policy]q
[R3]route-policy MED permit node 20
[R3]bgp 123
[R3-bgp]peer 34.0.0.4 route-policy MED export

4、使用Local Preference策略，确保R1通过R2到达192.168.1.0/24 

[R1]ip ip-prefix LP1 permit 192.168.1.0 24
[R1]route-policy LP1 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 LP1 permit node 20
[R1]bgp 123
[R1-bgp]peer 2.2.2.2 route-policy LP import

5、使用Local Preference策略，确保R1通过R3到达192.168.2.0/24 

[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 200
[R1-route-policy]q
[R1]route-policy LP1 permit node 20
[R1]bgp 123
[R1-bgp]peer 3.3.3.3 route-policy LP import

6、配置负载均衡，确保R1通过R2和R3到达192.168.3.0/24

[R1]bgp 123

[R1-bgp]maximum load-balancing 2

7、使用As策略，AS 500不接受任何始发于AS 123的路由 

[R5]ip as-path-filter 1 deny _123$

[R5]ip as-path-filter 1 permit .*

[R5]bgp 500

[R5-bgp]peer 15.0.0.1 as-path-filter 1 import 

8、使用自定义Community策略，确保192.168.3.0/24路由不会被发布到AS 500 

[R4]route-policy com permit node 10
[R4-route-policy]apply community 400:500
 
[R4]bgp 400
[R4-bgp]network 192.168.3.0 24 route-policy com
[R4-bgp]peer 24.0.0.2 advertise-community
[R4-bgp]peer 34.0.0.3 advertise-community
 
[R2]bgp 123
[R2-bgp]peer 1.1.1.1 advertise-community
 
[R3]bgp 123
[R3-bgp]peer 1.1.1.1 advertise-community
 
[R1]bgp 123
[R1-bgp]peer 15.0.0.5 advertise-community