In the 21st century, the Internet is an indispensable part of human life. For small families, we only need to buy a router with switch functions from an Internet company, and then connect to a network cable or Wi-Fi to access the Internet. But for large companies with hundreds or even thousands of people, it is obviously not enough to use only one or two machines. We need different switches,servers, routers and firewalls to work together. This requires building a huge system. How to correctly and reasonably plan the intranet structure and take safe protective measures is very important.