实验9:默认路由
所谓的默认路由，是指路由器在路由表中如果找不到到达目的网络的具体路由时，最后
会采用的路由。默认路由通常会在存根网络（Stub network，即只有一个出口的网络）中使
用。如图，图中左边的网络到Internet 上只有一个出口，因此可以在R2 上配置默认路
由。命令为：ip route 0.0.0.0 0.0.0.0 { 网关地址 | 接口 }
例子：ip route 0.0.0.0 0.0.0.0 s0/0
例子：ip route 0.0.0.0 0.0.0.0 12.12.12.2
1. 实验目的
通过本实验，读者可以掌握如下技能：
（1） 默认路由的使用场合
（2） 默认路由的配置
2. 实验拓扑
如图。
3. 实验步骤
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ho r0
r0(config)#no ip domain-loo
r0(config)#lin c 0
r0(config-line)#logg s
r0(config-line)#exec-t 00
r0(config-line)#exit
r0(config)#end
r0#
%SYS-5-CONFIG_I: Configured from console by console
r0#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r0(config)#int loo 1
%LINK-5-CHANGED: Interface Loopback1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
r0(config-if)#
r0(config-if)#ip add 3.3.3.3 255.255.255.0
r0(config-if)#int s1/1/0
r0(config-if)#ip add 192.168.23.2 255.255.255.0
r0(config-if)#clo r 64000
r0(config-if)#no sh
%LINK-5-CHANGED: Interface Serial1/1/0, changed state to up
r0(config-if)#
r0(config-if)#^Z
r0#
%SYS-5-CONFIG_I: Configured from console by console
r0#
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/1/0, changed state to up
r0#ping 192.168.23.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.23.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/3/6 ms
r0#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r0(config)#ip route 0.0.0.0 0.0.0.0 s1/1/0
r0(config)#
r0#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r0(config)#ip route 0.0.0.0 0.0.0.0 s1/1/0
r0(config)#no ip route 0.0.0.0 0.0.0.0 s1/1/0
r0(config)#ip route 2.2.2.2.255.255.255.0 s1/1/0
^
% Invalid input detected at '^' marker.
r0(config)#ip route 2.2.2.2 255.255.255.0 s1/1/0
r0(config)#ip route 3.3.3.3 255.255.255.0 s1/1/0
r0(config)#
Press RETURN to get started!
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ho r1
r1(config)#no ip domain-loo
r1(config)#lin c 0
r1(config-line)#logg s
r1(config-line)#exec-t
% Incomplete command.
r1(config-line)#exec-t 00
r1(config-line)#exit
r1(config)#int loo 1
%LINK-5-CHANGED: Interface Loopback1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
r1(config-if)#
r1(config-if)#ip add 2.2.2.2 255.255.255.0
r1(config-if)#exit
r1(config)#int s1/1/1
r1(config-if)#ip add 192.168.12.2 255.255.255.0
r1(config-if)#no sh
%LINK-5-CHANGED: Interface Serial1/1/1, changed state to down
r1(config-if)#exit
r1(config)#int s1/1/1
r1(config-if)#no ip add
r1(config-if)#ip add 192.168.23.1 255.255.255.0
r1(config-if)#clo r 64000
r1(config-if)#no sh
r1(config-if)#exit
r1(config)#int s1/1/0
r1(config-if)#ip add 192.168.12.2 255.255.255.0
r1(config-if)#no sh
%LINK-5-CHANGED: Interface Serial1/1/0, changed state to up
r1(config-if)#
r1(config-if)#exit
r1(config)#exit
r1#
%SYS-5-CONFIG_I: Configured from console by console
r1#ping
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/1/0, changed state to up
r1#ping 192.168.12.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.12.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/3/6 ms
r1#
%LINK-5-CHANGED: Interface Serial1/1/1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/1/1, changed state to up
r1#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES manual administratively down down
FastEthernet0/1 unassigned YES manual administratively down down
FastEthernet1/0 unassigned YES manual administratively down down
Serial1/1/0 192.168.12.2 YES manual up up
Serial1/1/1 192.168.23.1 YES manual up up
Loopback1 2.2.2.2 YES manual up up
Vlan1 unassigned YES manual administratively down down
r1#ping
Protocol [ip]:
Target IP address: 3.3.3.3
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 2.2.2.2
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
.....
Success rate is 0 percent (0/5)
r1#
r1#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r1(config)#ip route 1.1.1.1 255.255.255.0 s1/1/0
r1(config)#ip route 3.3.3.3 255.255.255.0 s1/1/1
r1(config)#exit
r1#
%SYS-5-CONFIG_I: Configured from console by console
r1#ping
Protocol [ip]:
Target IP address: 1.1.1.1
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 2.2.2.2
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/4/5 ms
r1#ping
Protocol [ip]:
Target IP address: 3.3.3.3
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 2.2.2.2
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 2.2.2.2
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/3/5 ms
r1#
Press RETURN to get started!
Router>en
Router#conf t
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#ho r2
r2(config)#no ip domain-loo
r2(config)#lin c 0
r2(config-line)#logg s
r2(config-line)#exec-t 00
r2(config-line)#exit
r2(config)#int s1/1/0
r2(config-if)#ip add 192.168.12.1 255.255.255.0
r2(config-if)#clo r 64000
r2(config-if)#no sh
%LINK-5-CHANGED: Interface Serial1/1/0, changed state to down
r2(config-if)#exit
r2(config)#int loo 1
%LINK-5-CHANGED: Interface Loopback1, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback1, changed state to up
r2(config-if)#
r2(config-if)#ip add 1.1.1.1 255.255.255.0
r2(config-if)#exit
r2(config)#exit
r2#
%SYS-5-CONFIG_I: Configured from console by console
r2#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES manual administratively down down
FastEthernet0/1 unassigned YES manual administratively down down
FastEthernet1/0 unassigned YES manual administratively down down
Serial1/1/0 192.168.12.1 YES manual down down
Serial1/1/1 unassigned YES manual administratively down down
Loopback1 1.1.1.1 YES manual up up
Vlan1 unassigned YES manual administratively down down
r2#
%LINK-5-CHANGED: Interface Serial1/1/0, changed state to up
%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1/1/0, changed state to up
r2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r2(config)#ip route 0.0.0.0 0.0.0.0 s1/1/0
r2(config)#
r2(config)#
r2(config)#^Z
r2#
%SYS-5-CONFIG_I: Configured from console by console
r2#ping
Protocol [ip]:
Target IP address: 2.2.2.2
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 1.1.1.1
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1
.....
Success rate is 0 percent (0/5)
r2#sh ip int b
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 unassigned YES manual administratively down down
FastEthernet0/1 unassigned YES manual administratively down down
FastEthernet1/0 unassigned YES manual administratively down down
Serial1/1/0 192.168.12.1 YES manual up up
Serial1/1/1 unassigned YES manual administratively down down
Loopback1 1.1.1.1 YES manual up up
Vlan1 unassigned YES manual administratively down down
r2#ping
Protocol [ip]:
Target IP address: 3.3.3.3
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Extended commands [n]: y
Source address or interface: 1.1.1.1
Type of service [0]:
Set DF bit in IP header? [no]:
Validate reply data? [no]:
Data pattern [0xABCD]:
Loose, Strict, Record, Timestamp, Verbose[none]:
Sweep range of sizes [n]:
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 3.3.3.3, timeout is 2 seconds:
Packet sent with a source address of 1.1.1.1
.....
Success rate is 0 percent (0/5)
r2#
r2#conf t
Enter configuration commands, one per line. End with CNTL/Z.
r2(config)#no ip route 0.0.0.0 0.0.0.0 s1/1/0
r2(config)#ip route 1.1.1.1 255.255.255.0
% Incomplete command.
r2(config)#ip route 1.1.1.1 255.255.255.0 s1/1/0
r2(config)#ip route 2.2.2.2 255.255.255.0 s1/1/0
r2(config)#
本文转自gauyanm 51CTO博客，原文链接：http://blog.51cto.com/gauyanm/234588，如需转载请自行联系原作者
