實驗?zāi)康模郝酚扇?/strong>

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命令檢測直連鏈路是否通暢

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命令檢測能否將包從RouterA發(fā)送到達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?。∈褂胐ebug ip packet命令來查看

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)

根據(jù)debug信息可以看出ping不成功是因為無法路由，使用show ip route來查看路由表

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

路由表中沒有192.168.2.0/24網(wǎng)絡(luò)的路由，需要手動添加靜態(tài)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

此時路由表發(fā)生變化，多了一條靜態(tài)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，但是信息表示數(shù)據(jù)包已經(jīng)發(fā)送成功，考慮ping是一個雙向過程，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與C，說明RouterB沒有問題。

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

發(fā)現(xiàn)路由器C沒有去往192.168.1.0/24網(wǎng)絡(luò)的路由信息，此時debug看RouterC ping RouterA的過程也證明了我們的推斷

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網(wǎng)絡(luò)的靜態(tài)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

退回特權(quán)模式，查看路由表變化

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

已經(jīng)創(chuàng)建了一條去往192.168.1.0/24網(wǎng)絡(luò)的路由，回到RouterA上測試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