R1(config)#int s1/0
R1(config-if)#ip address 192.168.1.1 255.255.255.0
R1(config-if)#clock rate 64000 设置时钟频率
R1(config-if)#no shutdown
R1(config-if)#encapsulation ppp 开启ppp认证
R1(config-if)#ppp pap sent-username R2 password cisco 认证用户及密码
R2(config)#username R2 password cisco
R2(config)#int s1/0
R2(config-if)#ip address 192.168.1.2 255.255.255.0
R2(config-if)#clock rate 64000
R2(config-if)#no shutdown
R2(config-if)#encapsulation ppp
R2(config-if)#ppp authentication pap 开启pap认证服务
R3(config)#username R3 password cisco
R3(config)#int s1/0
R3(config-if)#ip address 192.168.1.1 255.255.255.0
R3(config-if)#clock rate 64000
R3(config-if)#no shutdown
R3(config-if)#encapsulation ppp
R3(config-if)#ppp authentication pap
R3(config-if)#ppp pap sent-username R4 password cisco
R4(config)#username R4 password cisco
R4(config)#int s1/0
R4(config-if)#ip address 192.168.1.2 255.255.255.0
R4(config-if)#clock rate 64000
R4(config-if)#no shutdown
R4(config-if)#encapsulation ppp
R4(config-if)#ppp authentication pap
R4(config-if)#ppp pap sent-username R3 password cisco
