CCNA实验:
要求：1、完成设备基本配置
2、在R1、R2、R3上配置静态路由，保证全网可达
3、在R1、R3上去掉上一步配置的静态路由，改用默认路由，仍全网可达。
R1:
en conf t hostname R1 interf s0/0 ip address 192.168.12.1 255.255.255.0 no sh inter f1/0 ip address 192.168.1.254 255.255.255.0 no sh
R2:
en conf t hostname R2 interf s0/0 ip address 192.168.12.2 255.255.255.0 no sh interf s0/1 ip address 192.168.23.2 255.255.255.0 no sh
R3:
en conf t hostname R3 interf s0/0 ip address 192.168.23.3 255.255.255.0 no sh interf f1/0 ip address 192.168.2.254 255.255.255.0 no sh
PC1:
en conf t hostname PC1 no ip routing ip default-gateway 192.168.1.254 interf f0/0 ip address 192.168.1.1 255.255.255.0 no sh
PC2:
en conf t hostname PC2 no ip routing ip default-gateway 192.168.2.254 interf f0/0 ip address 192.168.2.1 255.255.255.0 no sh
