实验目的：路由全通
RouterA
RouterA#sho run
Building configuration…
Current configuration : 584 bytes
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname RouterA
!
logging rate-limit console 10 except errors
!
ip subnet-zero
no ip finger
!
no ip dhcp-client network-discovery
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Serial0
no ip address
shutdown
!
interface Serial1
ip address 192.168.1.1 255.255.255.0
clockrate 64000
!
ip kerberos source-interface any
ip classless
ip http server
!
!
!
line con 0
transport input none
line aux 0
line vty 0 4
!
End
RouterB
RouterB#sho run
Building configuration…
Current configuration : 393 bytes
!
version 12.2
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname RouterB
!
!
ip subnet-zero
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Serial0
ip address 192.168.2.2 255.255.255.0
!
interface Serial1
ip address 192.168.1.2 255.255.255.0
!
ip classless
ip http server
!
!
!
line con 0
line aux 0
line vty 0 4
!
End
RouterC
RouterC#show run
Building configuration…
Current configuration : 584 bytes
!
version 12.2
no service single-slot-reload-enable
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname RouterC
!
logging rate-limit console 10 except errors
!
ip subnet-zero
no ip finger
!
no ip dhcp-client network-discovery
!
!
!
!
interface Ethernet0
no ip address
shutdown
!
interface Serial0
ip address 192.168.2.3 255.255.255.0
clockrate 64000
!
interface Serial1
no ip address
shutdown
!
ip kerberos source-interface any
ip classless
ip http server
!
!
!
line con 0
transport input none
line aux 0
line vty 0 4
!
End
首先在RouterA上使用ping命令检测直连链路是否通畅
RouterA#ping 192.168.1.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.2, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms
再次使用ping命令检测能否将包从RouterA发送到达RouterC
RouterA#ping 192.168.2.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.3, timeout is 2 seconds:
…..
Success rate is 0 percent (0/5)
Ping命令失败！使用debug ip packet命令来查看
RouterA#debug ip packet
IP packet debugging is on
RouterA#ping 192.168.2.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.3, timeout is 2 seconds:
00:15:52: IP: s=192.168.1.1 (local), d=192.168.2.3, len 100, unroutable.
00:15:54: IP: s=192.168.1.1 (local), d=192.168.2.3, len 100, unroutable.
00:15:56: IP: s=192.168.1.1 (local), d=192.168.2.3, len 100, unroutable.
00:15:58: IP: s=192.168.1.1 (local), d=192.168.2.3, len 100, unroutable.
00:16:00: IP: s=192.168.1.1 (local), d=192.168.2.3, len 100, unroutable.
Success rate is 0 percent (0/5)
根据debug信息可以看出ping不成功是因为无法路由，使用show ip route来查看路由表
RouterA#show 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
C 192.168.1.0/24 is directly connected, Serial1
路由表中没有192.168.2.0/24网络的路由，需要手动添加静态路由
RouterA#conf t
Enter configuration commands, one per line. End with CNTL/Z.
RouterA(config)#ip route 192.168.2.0 255.255.255.0 S1
查看路由表
RouterA#sho ip rou
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
C 192.168.1.0/24 is directly connected, Serial1
S 192.168.2.0/24 is directly connected, Serial1
此时路由表发生变化，多了一条静态路由。
再次ping一下RouterC
RouterA#ping 192.168.2.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.3, timeout is 2 seconds:
00:21:43: IP: s=192.168.1.1 (local), d=192.168.2.3 (Serial1), len 100, sending.
00:21:45: IP: s=192.168.1.1 (local), d=192.168.2.3 (Serial1), len 100, sending.
00:21:47: IP: s=192.168.1.1 (local), d=192.168.2.3 (Serial1), len 100, sending.
00:21:49: IP: s=192.168.1.1 (local), d=192.168.2.3 (Serial1), len 100, sending.
00:21:51: IP: s=192.168.1.1 (local), d=192.168.2.3 (Serial1), len 100, sending.
Success rate is 0 percent (0/5)
依然不通，但是信息表示数据包已经发送成功，考虑ping是一个双向过程，于是到RouterB上去看一下
RouterB#ping 192.168.2.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 32/32/32 ms
RouterB#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 40/40/44 ms
RouterB可以ping通RouterA与C，说明RouterB没有问题。
去看一下RouterC的路由表
RouterC#sho ip rou
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
C 192.168.2.0/24 is directly connected, Serial0
发现路由器C没有去往192.168.1.0/24网络的路由信息，此时debug看RouterC ping RouterA的过程也证明了我们的推断
RouterC#debug ip pac
IP packet debugging is on
RouterC#ping 192.168.1.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.1.1, timeout is 2 seconds:
03:46:38: IP: s=192.168.2.3 (local), d=192.168.1.1, len 100, unroutable.
03:46:40: IP: s=192.168.2.3 (local), d=192.168.1.1, len 100, unroutable.
03:46:42: IP: s=192.168.2.3 (local), d=192.168.1.1, len 100, unroutable.
03:46:44: IP: s=192.168.2.3 (local), d=192.168.1.1, len 100, unroutable.
03:46:46: IP: s=192.168.2.3 (local), d=192.168.1.1, len 100, unroutable.
Success rate is 0 percent (0/5)
在RouterC上添加去往192.168.1.0/24网络的静态路由
RouterC#conf t
Enter configuration commands, one per line. End with CNTL/Z.
RouterC(config)#ip route 192.168.1.0 255.255.255.0 192.168.2.2
退回特权模式，查看路由表变化
RouterC(config)#exit
RouterC#
03:48:52: %SYS-5-CONFIG_I: Configured from console by console
RouterC#sho ip rou
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
S 192.168.1.0/24 [1/0] via 192.168.2.2
C 192.168.2.0/24 is directly connected, Serial0
已经创建了一条去往192.168.1.0/24网络的路由，回到RouterA上测试ping一下
RouterA#ping 192.168.2.3
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.168.2.3, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 76/85/112 ms