Research And Implementation Of Double-export Campus Network IP Accounting System

Double-export campus network means that to extend export bandwidth and reduce the international flux, compus connect the native ISP for another export to the internet, which is named double export campus network.The paper analyzes the current IP accountings mode and its main problems of the campus network management. For example, a accounting gateway makes the network wall up easily ; the SNMP accounting cannot make certain the time interval; the proxy accounting rely on too much handwork, bad system integration; on this condition ,the paper brings forward the combining of SNMP and NetFlow for the double export campus network. The NetFlow accounting is different from others on flow accounting, which reduces the influence on the bandwidth and network equipment stating flux, and which reduces the burden of network equipments byavoiding the uninterrupted request to the network equipment. The mode not only makes a router get particular information, but also use the SNMP accounting where the NetFlow cannot be used.On the actual project, the paper designs the NetFlow collecter that can receive the NetFlow message of V₁ and V₅ edition, and put the message to the cache that I designed. The middle disposal module uses the multithreading mode, basing on the experiment result, and overfull threads will use overfull CPU time parcels, then the writing thread capability descend. To avoiding it, we must confirm the thread number by the experiment report in receiving the UDP message .The message parser will parse SNMP and etNFlow messages into the same format. Aiming at being hard to confirm the SNMP gathering time interval, the paper advances a remedy precept: when the SNMP gathering program search the router table ,it records the rate of gathered datas and the cache total . If it is large and get the threshold, we will reduce the gathering time interval; if small, then increase. It is a mechanism of adjusting gathering frequency through analyzing the flux trend .At the same time, the paper also use the TRAP technique .When the router cache becomes fullsuddenly, the router will send a TRAP message to our TRAP collecter, the TRAP collector judges the TRAP class and informs the gathering thread for beginning work,which temporarily lightens the pressure of producing too many data overflow.The paper is made of two parts. One part is administration of networks system principle,the SNMP protocol and NetFlow protocol ; the other part ,I analyzed someone campus network structure and according to our theory ,design and develop an IP campus network accounting system.Although the paper do some work, that is not enough. For example, administration of networks security is our weakness.Certainly it is an integrated problem which is assorted with other network technique .I will try my best on it in the future.