1、通过gns3搭建拓扑图，如下
3、同样将R2 ,R3 的端口洧粽袄淖配置好IP地址R2#conf tEnter configuration commands, one per line. End with CNTL/Z.R2(co荏鱿胫协nfig)#int s2/0R2(config-if)#ip add 172.16.1.2 255.255.255.252R2(config-if)#no shR2(config-if)#*Aug 15 01:34:30.307: %LINK-3-UPDOWN: Interface Serial2/0, changed state to up*Aug 15 01:34:31.311: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/0, changed state to upR2(config-if)#int s2/1R2(config-if)#ip add 172.16.1.5 255.255.255.252R2(config-if)#no shR2(config-if)#int lo*Aug 15 01:35:02.865: %LINK-3-UPDOWN: Interface Serial2/1, changed state to up*Aug 15 01:35:03.867: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/1, changed state to upR2(config-if)#int lo 0R2(config-if)#ipadd*Aug 15 01:35:05.343: %LINEPROTO-5-UPDOWN: Line protocol on Interface Loopback0, changed state to upR2(config-if)#ip add 131.131.1.1 255.255.0.0R2(config-if)#no shR2(config-if)#*Aug 15 01:35:26.237: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial2/1, changed state to downR3的端口请自行配置！配置完成后通过show ip int bri ，查看端口信息
4、通过ping命令来确保直连端口的的连通性
