RIP v2 不连续子网的基本配置
配置如下配置看看有什么结果
R1：
R1（config）#intf0/0
R1（config-if）#ip add 172.16.1.254 255.255.255.0
R1（config-if）#no shutdown
R1（config-if）#int s0/0
R1（config-if）#ip add 192.1.1.1 255.255.255.0
R1（config-if）#no shutdown
R1（config）#router rip
R1（config-router）#version 2
R1（config-router）#network 192.1.1.0
R1（config-router）#network 172.16.1.0
R2:
R2（config）#int s0/0
R2（config-if）#ip add 192.1.1.2 255.255.255.0
R2（config-if）#no shutdown
R2（config）#int s0/1
R2（config-if）#ip add 193.1.1.1 255.255.255.0
R2（config-if）#no shutdown
R2（config-if）#cl ra 64000
R2（config）#router rip
R2（config-router）#version 2
R2（config-router）#network 192.1.1.0
R2（config-router）#network 193.1.1.0
R3:
R3（config）#int s0/1
R3（config-if）#ip add 193.1.1.2 255.255.255.0
R3（config-if）#no shutdown
R3（config）#int f0/0
R3（config-if）#ip add 172.16.2.254 255.255.255.0
R3（config-if）#no shutdown
R3（config）#router rip
R3（config-router）#version 2
R3（config-router）#network 193.1.1.0
R3（config-router）#network 172.16.2.0
查看一下各个路由器的路由条目：
R1：
R1#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
C 192.1.1.0/24 is directly connected, Serial0/0
R 193.1.1.0/24 [120/1] via 192.1.1.2, 00:00:11, Serial0/0
R2：
R2#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
R 172.16.0.0/16 [120/1] via 193.1.1.2, 00:00:18, Serial0/1
[120/1] via 192.1.1.1, 00:00:26, Serial0/0
C 192.1.1.0/24 is directly connected, Serial0/0
C 193.1.1.0/24 is directly connected, Serial0/1
R3：
R3#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 1 subnets
C 172.16.2.0 is directly connected, FastEthernet0/0
R 192.1.1.0/24 [120/1] via 193.1.1.1, 00:00:06, Serial0/1
C 193.1.1.0/24 is directly connected, Serial0/1
如上路由表可以看出在R1和R2的路由表中没有R3路由器F0/0接口的直连网段信息，
*Rip v2路由协议默认是自动汇总的（主类边界路由默认是自动汇总的对于Rip v2）
R1和R3都处于主类边界路由器都会做路由汇总，R1路由器的路由条目都学到了
R 172.16.0.0/16 [120/1] via 192.1.1.1, 00:00:22, Serial0/0
[120/1] via 193.1.1.2, 00:00:24, Serial0/1
如此可以看出到达172.16.0.0/16这个主类网络的有两个下一条端口可以到达，如此就可以造成路由环路是网络不能连通，（R1和R3都没有学到各自网段的路由条目）。
*R1和R3主类边界路由器进行了边界汇总172.16.0.0/16各自路由无法正确匹配所以影响网络。
解决方法：
在rip宣告中使用no auto-summary 是取消主类边界路由器的主动汇总，是之能精确匹配。配置如下：
R1：
R1(config)#router r
R1(config)#router rip
R1(config-router)#no a
R1(config-router)#no auto-summary
R1(config-router)#net 192.1.1.0
R1(config-router)#net 172.16.1.0
R2：
R2(config)#router r
R2(config-router)#no
R2(config-router)#no a
R2(config-router)#no auto-summary
R2(config-router)#net 192.1.1.0
R2(config-router)#net 193.1.1.0
R3：
R3(config)#router rip
R3(config-router)#no a
R3(config-router)#no auto-summary
R3(config-router)#net 193.1.1.0
R3(config-router)#net 172.16.2.0
查看各自的路由条目
R1：
R1#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/24 is subnetted, 2 subnets
C 172.16.1.0 is directly connected, FastEthernet0/0
R 172.16.2.0 [120/2] via 192.1.1.2, 00:00:02, Serial0/0
C 192.1.1.0/24 is directly connected, Serial0/0
R 193.1.1.0/24 [120/1] via 192.1.1.2, 00:00:02, Serial0/0
R2：
R2#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
R 172.16.0.0/16 is possibly down, routing via 192.1.1.1, Serial0/0
[120/1] via 193.1.1.2, 00:02:30, Serial0/1
R 172.16.1.0/24 [120/1] via 192.1.1.1, 00:00:04, Serial0/0
R 172.16.2.0/24 [120/1] via 193.1.1.2, 00:00:14, Serial0/1
C 192.1.1.0/24 is directly connected, Serial0/0
C 193.1.1.0/24 is directly connected, Serial0/1
R3：
R3#sh ip route
Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP
D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area
N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2
E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP
i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area
* - candidate default, U - per-user static route, o - ODR
P - periodic downloaded static route
Gateway of last resort is not set
172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks
R 172.16.0.0/16 is possibly down, routing via 193.1.1.1, Serial0/1
R 172.16.1.0/24 [120/2] via 193.1.1.1, 00:00:24, Serial0/1
C 172.16.2.0/24 is directly connected, FastEthernet0/0
R 192.1.1.0/24 [120/1] via 193.1.1.1, 00:00:24, Serial0/1
C 193.1.1.0/24 is directly connected, Serial0/1
用两台PC测试一下PC>ping 172.16.2.1
Pinging 172.16.2.1 with 32 bytes of data:
Reply from 172.16.2.1: bytes=32 time=109ms TTL=125
Reply from 172.16.2.1: bytes=32 time=125ms TTL=125
Reply from 172.16.2.1: bytes=32 time=113ms TTL=125
Reply from 172.16.2.1: bytes=32 time=110ms TTL=125