BGP的同步规则(上)

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。

2、配置完之后，看一下各路由器中学习到的全网bgp路由：

 

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

 

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：

 

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

 

 

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：

 

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

 

 

5、那么在R1/R2/R3都开启同步，看一下对EBGP有什么影响:

 

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

 

6 、发现R1和R2学不到150.150.1.0/24这条路由了：

 

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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