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BGP选路实验

news 来源：原创 2025/4/20 11:58:43

实验拓扑

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实验步骤

配置IP

配置ospf

R2
ospf 1 router-id 2.2.2.2 area 0.0.0.0 network 2.2.2.2 0.0.0.0 network 100.2.2.0 0.0.0.255 R3
ospf 1 router-id 3.3.3.3 area 0.0.0.0 network 3.3.3.3 0.0.0.0 network 100.4.4.0 0.0.0.255 R4
ospf 1 router-id 4.4.4.4 area 0.0.0.0 network 4.4.4.4 0.0.0.0 network 100.2.2.0 0.0.0.255 network 100.4.4.0 0.0.0.255

配置bgp

R1
bgp 100peer 100.1.1.2 as-number 200 peer 100.3.3.3 as-number 200 #ipv4-family unicastundo synchronizationnetwork 192.168.0.0 network 192.168.1.0 peer 100.1.1.2 enablepeer 100.1.1.2 route-policy AS importpeer 100.3.3.3 enableR2
bgp 200peer 4.4.4.4 as-number 200 peer 4.4.4.4 connect-interface LoopBack0peer 100.1.1.1 as-number 100 #ipv4-family unicastundo synchronizationpeer 4.4.4.4 enablepeer 4.4.4.4 next-hop-local peer 100.1.1.1 enablepeer 100.1.1.1 route-policy med exportR3
bgp 200peer 4.4.4.4 as-number 200 peer 4.4.4.4 connect-interface LoopBack3peer 100.3.3.1 as-number 100 #ipv4-family unicastundo synchronizationpeer 4.4.4.4 enablepeer 4.4.4.4 route-policy lp exportpeer 4.4.4.4 next-hop-local peer 100.3.3.1 enableR4
bgp 200peer 2.2.2.2 as-number 200 peer 2.2.2.2 connect-interface LoopBack0peer 3.3.3.3 as-number 200 peer 3.3.3.3 connect-interface LoopBack0#ipv4-family unicastundo synchronizationnetwork 192.168.2.0 network 192.168.3.0 peer 2.2.2.2 enablepeer 2.2.2.2 next-hop-local peer 3.3.3.3 enablepeer 3.3.3.3 route-policy pv importpeer 3.3.3.3 next-hop-local

通过修改MED使R1到达192.168.2.0/24网段的路由经过R3

R3
[r2-bgp]dis acl 2000
Basic ACL 2000, 1 rule
Acl's step is 5rule 5 permit source 192.168.2.0 0.0.0.255[r2-bgp]dis route-policy med
Route-policy : medpermit : 10 (matched counts: 7)Match clauses : if-match acl 2000Apply clauses : apply cost 1000 peer 100.1.1.1 route-policy med export

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通过修改Preferred-value属性，使R4 到达 192.168.0.0/24网段的路由经过R3

R4
[r4-bgp]dis acl 2000
Basic ACL 2000, 1 rule
Acl's step is 5rule 5 permit source 192.168.0.0 0.0.0.255 (4 matches)[r4-bgp]dis route-policy pv
Route-policy : pvpermit : 10 (matched counts: 4)Match clauses : if-match acl 2000Apply clauses : apply preferred-value 666 permit : 20 (matched counts: 4)peer 3.3.3.3 route-policy pv import

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通过修改AS_path属性，使R1到达192.168.3.0/24网段的路由经过 R3

R1
[r1-acl-basic-2005]dis this
[V200R003C00]
#
acl number 2005  rule 5 permit source 192.168.3.0 0.0.0.255 [r1-acl-basic-2005]dis route-policy AS
Route-policy : ASpermit : 10 (matched counts: 3)Match clauses : if-match acl 2005Apply clauses : apply as-path 200 200 200 additivepermit : 20 (matched counts: 3)peer 100.1.1.2 route-policy AS import

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通过修改Local-pref属性，使R4到达192.168.1.0/24网段的路由经过 R3

R3
acl number 2000  rule 5 permit source 192.168.1.0 0.0.0.255 [r3]dis route-policy lp
Route-policy : lppermit : 10 (matched counts: 2)Match clauses : if-match acl 2000Apply clauses : apply local-preference 999permit : 20 (matched counts: 2)peer 4.4.4.4 route-policy lp export