在一个大型网络中可能存在着多种路由协议，因此关系到路由重分发的问题。网络架构如下图所示：
架构说明
1 R1为总公司路由器；
2 R2、R5为上海分公司路由器；
3 R3、R4为杭州分公司路由器；
4 总公司和分公司之间使用OSPF协议，上海分公司使用RIP协议，而杭州分公司使用静态路由协议；
5 所有分公司访问公网都通过总公司路由器R1实现；
6 本地所带主机由Loopback1接口模拟；
7 Loopback0使用192.168.255.0/24网段并且作为Router ID；
一、配置基本信息
1.R1配置
R1(config)#hostname R1 R1(config)#int f0/0 R1(config-if)#ip add 10.0.0.1 255.255.255.252 R1(config-if)#no sh R1(config-if)#int f1/0 R1(config-if)#ip add 10.0.0.6 255.255.255.252 R1(config-if)#no sh R1(config-if)#int f2/0 R1(config-if)#ip add 172.16.31.1 255.255.255.252 R1(config-if)#no sh R1(config)#int loopback 0 R1(config-if)#ip add 192.168.255.1 255.255.255.0 R1(config-if)#no sh R1(config)#int loopback 1 R1(config-if)#ip add 192.168.1.1 255.255.255.0 R1(config-if)#no sh
R1(config)#router ospf 1 R1(config-router)#router-id 192.168.255.1 R1(config-router)#network 192.168.1.0 0.0.0.255 area 0 R1(config-router)#network 10.0.0.4 0.0.0.3 area 1 R1(config-router)#network 192.168.255.1 0.0.0.0 area 0 R1(config-router)#network 10.0.0.0 0.0.0.3 area 0
R1(config)#ip route 0.0.0.0 0.0.0.0 172.16.31.2
2.R2配置
R2(config)#hostname R2 R2(config)#int f0/0 R2(config-if)#ip add 10.0.0.2 255.255.255.252 R2(config-if)#no sh R2(config-if)#int f1/0 R2(config-if)#ip add 192.168.100.1 255.255.255.0 R2(config-if)#no sh R2(config)#int loopback 0 R2(config-if)#ip add 192.168.255.2 255.255.255.255 R2(config-if)#no sh
R2(config)#router ospf 1 R2(config-router)#router-id 192.168.255.2 R2(config-router)#network 10.0.0.0 0.0.0.3 area 0 R2(config-router)#network 192.168.255.2 0.0.0.0 area 0
R2(config)#router rip R2(config-router)#version 2 R2(config-router)#no auto-summary R2(config-router)#network 192.168.100.0
3.R3配置
R3(config)#hostname R3 R3(config)#int f1/0 R3(config-if)#ip add 10.0.0.5 255.255.255.252 R3(config-if)#no sh R3(config-if)#int f0/0 R3(config-if)#ip add 10.0.0.10 255.255.255.252 R3(config-if)#no sh R3(config)#int loopback 0 R3(config-if)#ip add 192.168.255.3 255.255.255.255 R3(config-if)#no sh
R3(config)#router ospf 1 R3(config-router)#router-id 192.168.255.3 R3(config-router)#network 10.0.0.4 0.0.0.3 area 1 R3(config-router)#network 192.168.255.3 0.0.0.0 area 1
R3(config)#ip route 192.168.3.0 255.255.255.0 10.0.0.9
4.R4配置
R4(config)#hostname R4 R4(config)#int f0/0 R4(config-if)#ip add 10.0.0.9 255.255.255.252 R4(config-if)#no sh R4(config)#int loopback 0 R4(config-if)#ip add 192.168.255.4 255.255.255.255 R4(config-if)#no sh R4(config)#int loopback 1 R4(config-if)#ip add 192.168.3.1 255.255.255.0 R4(config-if)#no sh
R4(config)#ip route 0.0.0.0 0.0.0.0 10.0.0.10
5.R5配置
R5(config)#hostname R5 R5(config)#int f0/0 R5(config-if)#ip add 192.168.100.2 255.255.255.0 R5(config-if)#no sh R5(config)#int loopback 1 R5(config-if)#ip add 192.168.2.1 255.255.255.0 R5(config-if)#no sh
R5(config)#router rip R5(config-router)#version 2 R5(config-router)#no auto-summary R5(config-router)#network 192.168.100.0 R5(config-router)#network 192.168.2.0
6.Internet配置
Internet(config)#hostname Internet Internet(config)#int f0/0 Internet(config-if)#ip add 172.16.31.2 255.255.255.252 Internet(config-if)#no sh Internet(config)#int loopback 1 Internet(config-if)#ip add 59.56.61.1 255.255.255.0 Internet(config-if)#no sh
查看路由表：
R1#sh ip route Codes: C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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 172.16.31.2 to network 0.0.0.0 172.16.0.0/30 is subnetted, 1 subnets C 172.16.31.0 is directly connected, FastEthernet2/0 10.0.0.0/30 is subnetted, 2 subnets C 10.0.0.0 is directly connected, FastEthernet0/0 C 10.0.0.4 is directly connected, FastEthernet1/0 192.168.255.0/24 is variably subnetted, 3 subnets, 2 masks O 192.168.255.3/32 [110/2] via 10.0.0.5, 00:21:37, FastEthernet1/0 O 192.168.255.2/32 [110/2] via 10.0.0.2, 00:31:22, FastEthernet0/0 C 192.168.255.0/24 is directly connected, Loopback0 C 192.168.1.0/24 is directly connected, Loopback1 S* 0.0.0.0/0 [1/0] via 172.16.31.2
二、配置路由重分发：
1.路由器R1重发布默认路由
R1(config)#router ospf 1 R1(config-router)#default-information originate always
2.路由器R2重分发
R2(config)#router ospf 1 R2(config-router)#redistribute rip subnets R2(config)#router rip R2(config-router)#redistribute ospf 1 metric 3
3.路由器R3重发布静态路由和直连路由：
R3(config)#router ospf 1 R3(config-router)#redistribute static subnets R3(config-router)#redistribute connected subnets
三、验证网络通信是否正常
R3#sh ip route Codes: C - connected, S - static, 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 i - IS-IS, su - IS-IS summary, 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 10.0.0.6 to network 0.0.0.0 10.0.0.0/30 is subnetted, 3 subnets C 10.0.0.8 is directly connected, FastEthernet0/0 O IA 10.0.0.0 [110/2] via 10.0.0.6, 00:02:31, FastEthernet1/0 C 10.0.0.4 is directly connected, FastEthernet1/0 192.168.255.0/32 is subnetted, 3 subnets C 192.168.255.3 is directly connected, Loopback0 O IA 192.168.255.2 [110/3] via 10.0.0.6, 00:02:31, FastEthernet1/0 O IA 192.168.255.1 [110/2] via 10.0.0.6, 00:02:31, FastEthernet1/0 192.168.1.0/32 is subnetted, 1 subnets O IA 192.168.1.1 [110/2] via 10.0.0.6, 00:02:33, FastEthernet1/0 O E2 192.168.2.0/24 [110/20] via 10.0.0.6, 00:02:33, FastEthernet1/0 O E2 192.168.100.0/24 [110/20] via 10.0.0.6, 00:02:33, FastEthernet1/0 S 192.168.3.0/24 [1/0] via 10.0.0.9 O*E2 0.0.0.0/0 [110/1] via 10.0.0.6, 00:02:35, FastEthernet1/0
R4#ping 192.168.2.1 source 192.168.3.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 192.168.2.1, timeout is 2 seconds: Packet sent with a source address of 192.168.3.1 !!!!!
R5#ping 10.0.0.5 source 192.168.2.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 10.0.0.5, timeout is 2 seconds: Packet sent with a source address of 192.168.2.1 !!!!!
四、在R1路由器上配置NAT
R1(config)#int f1/0 R1(config-if)#ip nat inside R1(config)#int f0/0 R1(config-if)#ip nat inside R1(config)#int f2/0 R1(config-if)#ip nat outside R1(config)#access-list 1 permit any R1(config)#ip nat inside source list 1 int f2/0 overload
测试内网访问外网的连通性
R5#ping 59.56.61.1 source 192.168.2.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 59.56.61.1, timeout is 2 seconds: Packet sent with a source address of 192.168.2.1 !!!!!
R4#ping 59.56.61.1 source 192.168.3.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 59.56.61.1, timeout is 2 seconds: Packet sent with a source address of 192.168.3.1 !!!!!
当然，我们可以禁止192.168.2.0的网段对外网的访问：
R1(config)#no access-list 1 R1(config)#access-list 1 deny 192.168.2.0 0.0.0.255 R1(config)#access-list 1 permit any R1(config)#ip nat inside source list 1 interface f2/0 overload
R5#ping 59.56.61.1 source 192.168.2.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 59.56.61.1, timeout is 2 seconds: Packet sent with a source address of 192.168.2.1 .....
R4#ping 59.56.61.1 source 192.168.3.1 Type escape sequence to abort. Sending 5, 100-byte ICMP Echos to 59.56.61.1, timeout is 2 seconds: Packet sent with a source address of 192.168.3.1 !!!!!
