* - candidate default, U - per-user static route, o - ODR

　　P - periodic downloaded static route

　　Gateway of last resort is not set

　　3.0.0.0/24 is subnetted, 1 subnets

　　S       3.3.3.0 [1/0] via 23.1.1.3

　　12.0.0.0/24 is subnetted, 1 subnets

　　C       12.1.1.0 is directly connected, Serial0/0

　　23.0.0.0/24 is subnetted, 1 subnets

　　C       23.1.1.0 is directly connected, Serial0/1

　　S    192.168.1.0/24 [1/0] via 12.1.1.1

　　r3#sh ip ro

　　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

　　3.0.0.0/24 is subnetted, 1 subnets

　　C       3.3.3.0 is directly connected, Loopback0

　　12.0.0.0/24 is subnetted, 1 subnets

　　S       12.1.1.0 [1/0] via 23.1.1.2

　　23.0.0.0/24 is subnetted, 1 subnets

　　C       23.1.1.0 is directly connected, Serial0/0

　　S    192.168.1.0/24 [1/0] via 23.1.1.2

　　排错命令:

　　ping 3.3.3.3

　　tracert 3.3.3.3

　　traceroute 3.3.3.3

　　sh int s0/0

　　sh ip int s0/0

　　sh ip int brief

　　sh arp

　　clear arp

　　sh controllers s0/0            查看端口硬件信息

　　编辑特别推荐:

　　通过的CCNA经验体会