一、拓扑图：
二、BGP同步规则：
1、配置完各路由器的IP地址和BGP协议。R2和R4再互指邻居。同时注意把R2上的router-id指高。以便R4能学到完整路由。
1、配置完各路由器的IP地址和BGP协议。R2和R4再互指邻居。同时注意把R2上的router-id指高。以便R4能学到完整路由。
2、配置完之后，看一下各路由器中学习到的全网bgp路由：
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R1#sh ip route bgp
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.4 [20/0] via 10.1.255.2, 01:30:06
B 10.1.255.12 [20/0] via 10.1.255.2, 01:30:06
B 10.1.255.8 [20/0] via 10.1.255.2, 01:30:36
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [20/0] via 10.1.255.2, 01:30:06
R2#sh ip route bgp
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.12 [200/0] via 10.1.255.10, 01:31:06
B 10.1.255.8 [200/0] via 10.1.255.6, 01:31:13
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [20/0] via 10.1.255.1, 01:31:13
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [200/0] via 10.1.255.14, 01:31:01
R3#sh ip route bgp
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.0 [200/0] via 10.1.255.5, 01:31:21
B 10.1.255.12 [200/0] via 10.1.255.10, 04:52:27
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [200/0] via 10.1.255.1, 01:31:15
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [200/0] via 10.1.255.14, 04:52:22
R4#sh ip route bgp
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.4 [200/0] via 10.1.255.9, 01:32:32
B 10.1.255.0 [200/0] via 10.1.255.5, 01:31:39
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [200/0] via 10.1.255.1, 01:31:34
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [20/0] via 10.1.255.14, 04:52:46
R5#sh ip route bgp
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.4 [20/0] via 10.1.255.13, 04:53:03
B 10.1.255.0 [20/0] via 10.1.255.13, 01:31:56
B 10.1.255.8 [20/0] via 10.1.255.13, 04:53:03
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [20/0] via 10.1.255.13, 01:31:25
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3、从上面看到，各路由器全网的BGP路由都能学到，那么现在我们根据拓扑图在R2/R3/R4中运行ospf 协议。看一下对整个网络的影响：
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R2(config)#router ospf 1
R2(config-router)#net 10.1.255.0 0.0.0.3 area 0
R2(config-router)#net 10.1.255.4 0.0.0.3 area 0
R3(config)#router ospf 1
R3(config-router)#net 10.1.255.4 0.0.0.3 area 0
R3(config-router)#net 10.1.255.8 0.0.0.3 area 0
R4(config)#router ospf 1
R4(config-router)#net 10.1.255.8 0.0.0.3 area 0
R4(config-router)#net 10.1.255.12 0.0.0.3 area 0
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4、在配置完之后，发现对所有的路由器并没有影响，只是启用了ospf区域的路由以o来显示，但都能学习到全网的路由：
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R1#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.4 [20/0] via 10.1.255.2, 00:00:34
C 10.1.255.0 is directly connected, Serial1/1
B 10.1.255.12 [20/0] via 10.1.255.2, 00:00:03
B 10.1.255.8 [20/0] via 10.1.255.2, 00:00:03
130.130.0.0/24 is subnetted, 1 subnets
C 130.130.1.0 is directly connected, Loopback0
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [20/0] via 10.1.255.2, 00:00:03
R2#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
C 10.1.255.4 is directly connected, Serial1/1
C 10.1.255.0 is directly connected, Serial1/0
O 10.1.255.12 [110/192] via 10.1.255.6, 00:10:33, Serial1/1
O 10.1.255.8 [110/128] via 10.1.255.6, 00:10:33, Serial1/1
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [20/0] via 10.1.255.1, 00:07:06
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [200/0] via 10.1.255.14, 00:06:54
R3#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
C 10.1.255.4 is directly connected, Serial1/0
O 10.1.255.0 [110/128] via 10.1.255.5, 00:11:10, Serial1/0
O 10.1.255.12 [110/128] via 10.1.255.10, 00:11:10, Serial1/1
C 10.1.255.8 is directly connected, Serial1/1
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [200/0] via 10.1.255.1, 00:07:42
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [200/0] via 10.1.255.14, 00:07:31
R4#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
O 10.1.255.4 [110/128] via 10.1.255.9, 00:11:47, Serial1/0
O 10.1.255.0 [110/192] via 10.1.255.9, 00:11:47, Serial1/0
C 10.1.255.12 is directly connected, Serial1/1
C 10.1.255.8 is directly connected, Serial1/0
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [200/0] via 10.1.255.1, 00:08:07
150.150.0.0/24 is subnetted, 1 subnets
B 150.150.1.0 [20/0] via 10.1.255.14, 00:08:07
R5#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.4 [20/0] via 10.1.255.13, 00:08:31
B 10.1.255.0 [20/0] via 10.1.255.13, 00:08:31
C 10.1.255.12 is directly connected, Serial1/0
B 10.1.255.8 [20/0] via 10.1.255.13, 00:08:00
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [20/0] via 10.1.255.13, 00:08:31
150.150.0.0/24 is subnetted, 1 subnets
C 150.150.1.0 is directly connected, Loopback0
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5、那么在R1/R2/R3都开启同步，看一下对EBGP有什么影响:
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R2(config)#router bgp 64513
R2(config-router)#syn
R3(config)#router bgp 64513
R3(config-router)#syn
R4(config)#router bgp 64513
R4(config-router)#syn
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6、发现R1和R2学不到150.150.1.0/24这条路由了：
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R1#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
B 10.1.255.4 [20/0] via 10.1.255.2, 00:08:49
C 10.1.255.0 is directly connected, Serial1/1
B 10.1.255.12 [20/0] via 10.1.255.2, 00:08:49
B 10.1.255.8 [20/0] via 10.1.255.2, 00:08:49
130.130.0.0/24 is subnetted, 1 subnets
C 130.130.1.0 is directly connected, Loopback0
R2#sh ip route
………………
10.0.0.0/30 is subnetted, 4 subnets
C 10.1.255.4 is directly connected, Serial1/1
C 10.1.255.0 is directly connected, Serial1/0
O 10.1.255.12 [110/192] via 10.1.255.6, 00:49:28, Serial1/1
O 10.1.255.8 [110/128] via 10.1.255.6, 00:49:28, Serial1/1
130.130.0.0/24 is subnetted, 1 subnets
B 130.130.1.0 [20/0] via 10.1.255.1, 00:09:00
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(一篇发不了，请接着看下篇)
本文转自wxs-163 51CTO博客，原文链接:http://blog.51cto.com/supercisco/268997