Extended Operation And Application Research On RMON Alarm

RMON, Remote Network Monitoring, is a kind of MIB (Management Information Base) protocol, and it defines standard function and interface for monitoring network. RMON makes network management terminal and remote probe based on SNMP be able to communicate with each other. Alarm is one characteristic operation of RMON function. Alarm group in RMON firstly defines a pair of thresholds relative to network performance, and if one of the thresholds is crossed, trap information will be generated and reported to network management station.Public protocol prescribes alarm variable in RMON must be Object Identifier of some special variable, and this definition results in RMON can only monitor individual network performance rather than local network performance. In more and more complex network environment, traditional criterion restriction to alarm variable makes it difficulty for alarm group to satisfy requirement from synthesis network performance.To solve problem above, on the basis of public protocol, the measure of extending alarm function is given in the thesis, and new correlative criterion in MIB is established: the selection scope of alarm variable is extended from one variable defined by MIB to multiple variables, namely, original alarm object corresponds to one variable, and extended alarm variable corresponds to alarm expression consists of multiple variables. In this alarm expression, every variable represents part of network state, and then the extended alarm variable could reflect the combinatorial change of many variables. Furthermore, sampling type and some other parameter is also expanded, and working mode of alarm group becomes more agile.Program of deciphering and calculating alarm expression is designed in the thesis, and on the foundation of real-time operating system vxWorks and bottom software interface, by tool of programming language C, the program is implemented. Finally, code is embedded into communication device(switcher,router etc), through strict test and factual application in network, extended alarm group runs well.Extended RMON alarm group has been successfully make use of in large-scale network, and the monitoring scope is wider, the result got is more objective, the ability of exploring in network management is strengthened greatly.