The Research And Implementation Of The Key Problems In SNMP Network Management System

Along with the swift and violent development of network technology, the application area of network becomes more and more large, functions are more complicated as its growing. Network has turned into a necessary in people's life. Therefore it brought greater challenge to network management. In this case.a perfect network management system can ensure the network stable and credible running,and also it is the basis of network performance analyse.Numerous companies have developed commercial network management software,such as IBM's NetView,HP's Open View, Cisco's Cisco Works.But these softwares are mainly on manage truck routers or based on private manufacturer devices,so they are not completely fit enterprise LAN management.Because in enterprise LAN,there are fewer trunk devices and their locations are at the edge of Internet,so the management requires are more fine,even detail to every switch,every port,every user.Therefore it brings forward higher demand to netwrk topology arithmetic which is the main function in network management. It needs to discovery link layer switches. And now the network constructions are more complicated than before, equipments in the network are various,these all increase the difficulty to network topology arithmetic.Crrently,the first link layer discovery arithmetic was put forward by Bell Labs and Lucent Technologies.It can discover devices in large heterogemeous and multi-subnet Ethernet networks.the arithmetic is based on standard SNMP MIB information supported extensively in current IP network, mainly to collect the MAC forward information in FDB table.The main thought of the arithmetic is to probe into the equipments in a sunet network by using ICMP packets.For the ICMP packets would be forwarded by devices in the link layer and link layer devices would store MAC inforamtion in their FDB Table,the arithmetic can get all the link layer topology accroding to these MAC tracks.But the arithmetic is based on these hypotheses:there is no communication between sub-trees in the subnet network;all equipments' mac table are empty before probed;ICMP is supported in the network environment. In actual situations,these hypothesesis are very difficult to establish at the same time.This thesis will put forward a leaf-node judgement method based on link layer topology discovery arithmetic,it is an absolutely new method to discover link layer topology. Leaf-node judgement method is also based on SNMP MIB FDB information.This method will choose these switches satisfied the condition of become a leaf-node first,a leaf-node means all the macs in FDB in this switch would forward to only one port(excluded other not switches' macs).And these leaf-node switches have a characteristic that their neighbour switches have only one switch's MACs at the port which is connect to them.According to these,we can get a pair of connection relationship.Then get all the connection topology by creating leaf-node one by one.In LAN management,usually there is a demand to manage specific user.User IP locating method can find out the nearest switch port where user connect to network quickly and accurately.Then It can manage this port to control user behavior to achieve the aim of user management.User IP locating method replaces the work which is loaded down with trivial details which is did by network manager,and it can lighten the burden of network manager.At last,it introduced a network management system which is developed for campus network based on SNMP and WEB technology.This network management system based on B/S technology can fully give out the advantages of B/S model,greatly enhance the network management ability.