Along with the computer network popularization and the development,our life and the work all more and more relies on the network. Howeverthe network hacker's attack, network virus's being in flood alreadyconstituted with each kind of network service safe request to thenetwork security urgent demand. Now, my school has completed take 2Cisco 65 series switchboards as the core level, 4 Cisco 45 seriesswitchboards is the gathering level, series switchboard and so on 110harbors for turns on the level three exchanges pattern campus network,is four wide ranges 9 buildings users clears data message 2,200. Howprotects the campus net not the interior or the exterior safe threat,guaranteed the campus net the normal operation then became heavilycenter has been heavy. This topic goal lies in through to the networksecurity theory study, thus the understanding garden area networksecurity basic principle, the practical significance, the familiareach kind of network equipment use and the disposition, familiarrealizes network security each method and the method. In the fullstudy network security knowledge, the familiar each kind of networkequipment, in the security technology foundation, the use networklaboratory existing condition, independently designs and realizes thecampus net simulation run, simulates VLAN, the access control throughthe experiment tabulates as well as technology and so on firewall inthe network security domain practical application.