静态路由也能胜任多网段之间进行通信

昨天，和朋友在机房讨论组网问题，当讨论到路由器间通信时，朋友问起为什么非要配置路由选择协议。以前一般是根据配置手册或者经验配置也没有仔细考虑过这个问题。想了想，应该是这样理解的（如下）。

如果多个网段之间要实现通信，必须使用路由器，这个毫无疑问。如果多个网段之间存在多个可选择的路径，最方便的是采取配置路由选择协议的方法，简单点的网络可以采用RIP协议，如果是复杂的网络则可以采用OSPF。当然在选择的路径不多时也可以采用静态路由的方法。

但是，当多个网段之间只有一条路径时，那么仅仅是配置静态路由就足够了。如果是在企业中工作，那么往往配置简单的静态路由就足够了。

为了更有说服力和便于理解我用CPT（Cisco Packet Tracer）演示了一下。

拓扑图如下图所示：

分别有四个网段，10.0.0.0/8、112.237.228.0/24、192.168.10.0/24、211.86.104.0/24。

静态路由设置如下：

ip route 192.168.10.0 255.255.255.0 112.237.228.1
ip route 211.86.104.0 255.255.255.0 112.237.228.1


ip route 10.0.0.0 255.0.0.0 112.237.228.244
ip route 211.86.104.0 255.255.255.0 192.168.10.1


ip route 112.237.228.0 255.255.255.0 192.168.10.2
ip route 10.0.0.0 255.0.0.0 192.168.10.2

配置如下：

1.PC0的IP配置：

Packet Tracer PC Command Line 1.0
PC>ipconfig

IP Address......................: 10.0.0.3
Subnet Mask.....................: 255.0.0.0
Default Gateway.................: 10.0.0.1

PC>

2.PC1的IP配置：

Packet Tracer PC Command Line 1.0
PC>ipconfig

IP Address......................: 211.86.104.52
Subnet Mask.....................: 255.255.255.0
Default Gateway.................: 211.86.104.254

PC>

3.R1的配置：

Router>enable
Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#hostname R1
R1(config)#interface FastEthernet0/1
R1(config-if)#ip address 10.0.0.1 255.0.0.0
R1(config-if)#no shutdown


%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up
R1(config-if)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console

R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#int f0/0
R1(config-if)#ip addr 112.237.228.244 255.255.255.0
R1(config-if)#no shutdown


%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
R1(config-if)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console


R1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R1(config)#ip route 192.168.10.0 255.255.255.0 112.237.228.1
R1(config)#ip route 211.86.104.0 255.255.255.0 112.237.228.1
R1(config)#end
R1#
%SYS-5-CONFIG_I: Configured from console by console

R1#

4.R2的配置：

Router>enable
Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#hostname R2
R2(config)#
R2(config)#interface FastEthernet0/1
R2(config-if)#ip address 112.237.228.1 255.255.255.0
R2(config-if)#no shutdown


%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up
R2(config-if)#
R2(config-if)#exit
R2(config)#interface FastEthernet0/0
R2(config-if)#ip address 192.168.10.2 255.255.255.0
R2(config-if)#no shutdown


%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up
R2(config-if)#end
R2#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R2(config)#ip route 10.0.0.0 255.0.0.0 112.237.228.244
R2(config)#ip route 211.86.104.0 255.255.255.0 192.168.10.1
R2(config)#end
R2#
%SYS-5-CONFIG_I: Configured from console by console

R2#

5.R3的配置： 

Router>enable
Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#hostname R3
R3(config)#
R3(config)#interface FastEthernet0/1
R3(config-if)#ip address 192.168.10.1 255.255.255.0
R3(config-if)#no shutdown


%LINK-5-CHANGED: Interface FastEthernet0/1, changed state to up
R3(config-if)#
R3(config-if)#exit
R3(config)#interface FastEthernet0/0
R3(config-if)#ip address 211.86.104.254 255.255.255.0
R3(config-if)#no shutdown

R3(config-if)#
%LINK-5-CHANGED: Interface FastEthernet0/0, changed state to up


R3>enable
R3#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
R3(config)#ip route 112.237.228.0 255.255.255.0 192.168.10.2
R3(config)#ip route 10.0.0.0 255.0.0.0 192.168.10.2
R3(config)#end
R3#
%SYS-5-CONFIG_I: Configured from console by console

R3#

6.使用tracert进行测试：

测试从PC0能否路由到PC1。

结果表明测试成功。

测试从PC1能否路由到PC0。

结果表明测试成功。