1. First, connect the two servers and two PCs online.
2. Then start all of them, remember to open all terminals after starting
3. After opening the terminal, start configuring two pcs
pc1：
pc2：
4. After configuring the pc, start configuring the two routers
Router m3:
At the beginning, he was still working on a program that he didn’t know, and when he pressed enter, he would be prompted to press ctrl+c or ctrl+d to jump out of this program, so he listened to him and pressed ctrl+c to jump out, and then pressed enter again. Enter sys to enter the operating system.
Because the two ports are not connected to each other, you have to set it yourself
Router m4: 
5. Then check if there is a newly set line in the two routers
m3：
m4:
6. Then the two PCs try to ping each other
It is also the first sys to enter the operating system, and then ping will do.
pc1 ping pc2：
pc2 ping pc1：
It's all done, everyone is happy hahaha. md.