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这个是实验采用思科路由器，利用secondary address来实现RIPV1的不连续的子网，整个过程如下：
1、按照图中的示例配置IP地址，使用ping命令确保网络连通性。
2、在R3 R4 R5上分别查看路由表。
R3(config-router)#do sh ip route
10.0.0.0/24 is subnetted, 2 subnets
R 10.1.45.0 [120/1] via 10.1.34.2, 00:00:25, Serial1/1
C 10.1.34.0 is directly connected, Serial1/1
192.168.1.0/24 is variably subnetted, 4 subnets, 2 masks
R 192.168.1.8/29 [120/1] via 192.168.1.18, 00:00:11, FastEthernet0/0
C 192.168.1.0/30 is directly connected, Loopback0
R 192.168.1.0/29 [120/1] via 192.168.1.17, 00:00:04, FastEthernet0/0
C 192.168.1.16/29 is directly connected, FastEthernet0/0
//R3上没有收到来自于R4的关于192.168.1.0的路由
R4(config-router)#do sh ip route
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.45.0 is directly connected, Serial1/1
C 10.1.34.0 is directly connected, Serial1/0
R 192.168.1.0/24 [120/1] via 10.1.34.1, 00:00:25, Serial1/0
[120/1] via 10.1.45.2, 00:00:01, Serial1/1
//R4从R3，R5分别收到路由，因此有两个关于192.168.1.0 的路由，metric都为1，RIP默认进行负载均衡。
R5(config-router)#do sh ip route
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.45.0 is directly connected, Serial1/0
R 10.1.34.0 [120/1] via 10.1.45.1, 00:00:15, Serial1/0
192.168.1.0/29 is subnetted, 1 subnets
C 192.168.1.24 is directly connected, Loopback0
//R5上也只有一条关于192.168.1.0的路由
3、为了实现R1 R2上的路由能够正确的传到R5，需要在沿途确保连续的子网没有被分割。配置secondary address
R3(config)#int s1/1
R3(config-if)#ip add 192.168.1.33 255.255.255.248 sec
R4(config)#int s1/0
R4(config-if)#ip add 192.168.1.34 255.255.255.248 sec
R4(config-if)#
R4(config-if)#
R4(config-if)#int s1/1
R4(config-if)#ip add 192.168.1.41 255.255.255.248 sec
R4(config-if)#exit
R4(config)#router rip
R4(config-router)#net 192.168.1.0
R5(config)#int s1/0
R5(config-if)#ip add 192.168.1.42 255.255.255.248 sec
4、在R1 R3 R4 上查看路由表
R1(config-router)#do sh ip route
http://www.luyouqiwang.com/15574/
Gateway of last resort is not set
R 10.0.0.0/8 [120/1] via 192.168.1.19, 00:00:14, FastEthernet0/0
192.168.1.0/29 is subnetted, 6 subnets
R 192.168.1.40 [120/2] via 192.168.1.19, 00:00:14, FastEthernet0/0
R 192.168.1.32 [120/1] via 192.168.1.19, 00:00:14, FastEthernet0/0
R 192.168.1.8 [120/1] via 192.168.1.18, 00:00:10, FastEthernet0/0
C 192.168.1.0 is directly connected, Loopback0
R 192.168.1.24 [120/3] via 192.168.1.19, 00:00:14, FastEthernet0/0
C 192.168.1.16 is directly connected, FastEthernet0/0
//子网192.168.1.24通过RIP传递过来，metric为3跳
R3(config-router)#do sh ip route
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 3 subnets
R 10.0.0.0 [120/1] via 192.168.1.34, 00:00:00, Serial1/1
R 10.1.45.0 [120/1] via 10.1.34.2, 00:00:00, Serial1/1
C 10.1.34.0 is directly connected, Serial1/1
192.168.1.0/24 is variably subnetted, 7 subnets, 2 masks
R 192.168.1.40/29 [120/1] via 192.168.1.34, 00:00:00, Serial1/1
C 192.168.1.32/29 is directly connected, Serial1/1
R 192.168.1.8/29 [120/1] via 192.168.1.18, 00:00:07, FastEthernet0/0
C 192.168.1.0/30 is directly connected, Loopback0
R 192.168.1.0/29 [120/1] via 192.168.1.17, 00:00:01, FastEthernet0/0
[120/1] via 10.1.34.2, 00:00:00, Serial1/1
R 192.168.1.24/29 [120/2] via 192.168.1.34, 00:00:00, Serial1/1
C 192.168.1.16/29 is directly connected, FastEthernet0/0
//此时在R3上可以看到关于192.168.1.0各个子网的明细路由。
R4(config-router)#do sh ip route
10.0.0.0/24 is subnetted, 2 subnets
C 10.1.45.0 is directly connected, Serial1/1
C 10.1.34.0 is directly connected, Serial1/0
192.168.1.0/29 is subnetted, 6 subnets
C 192.168.1.40 is directly connected, Serial1/1
C 192.168.1.32 is directly connected, Serial1/0
R 192.168.1.8 [120/2] via 192.168.1.33, 00:00:01, Serial1/0
R 192.168.1.0 [120/1] via 10.1.34.1, 00:00:01, Serial1/0
[120/1] via 10.1.45.2, 00:00:15, Serial1/1
R 192.168.1.24 [120/1] via 192.168.1.42, 00:00:15, Serial1/1
R 192.168.1.16 [120/1] via 192.168.1.33, 00:00:01, Serial1/0
//R4上也收到了明细路由
实验总结：
RIPV1默认在网络边界汇总网络，这样的话在R3上10.0.0.0网络边界会将192.168.1.0的各个子网汇总为192.168.1.0，因此整个网络的路由是不正确的。
通过配置 了secondary address之后，在网络边界延续29位的子网，使得整 个网络的路由能够正常传递。 | 
