34 RMON CONFIGURATIONIntroduction to RMON Remote monitoring (RMON) is a kind of management information base (MIB)defined by Internet Engineering Task Force (IETF). It is an important enhancementmade to MIB II standards. RMON is mainly used to monitor the data traffic across anetwork segment or even the entire network, and is currently a commonly usednetwork management standard.An RMON system comprises of two parts: the network management station(NMS) and the agents running on network devices. RMON agents operate onnetwork monitors or network probes to collect and keep track of the statistics ofthe traffic across the network segments to which their ports connect, such as thetotal number of the packets on a network segment in a specific period of time andthe total number of packets successfully sent to a specific host.■ RMON is fully based on SNMP architecture. It is compatible with the currentSNMP implementations.■ RMON enables SNMP to monitor remote network devices more effectively andactively, thus providing a satisfactory means of monitoring remote subnets.■ With RMON implemented, the communication traffic between NMS and SNMPagents can be reduced, thus facilitating the management of large-scaleinternetworks.Working Mechanism ofRMONRMON allows multiple monitors. It can collect data in the following two ways:■ Using the dedicated RMON probes. When an RMON system operates in thisway, the NMS directly obtains management information from the RMONprobes and controls the network resources. In this case, all information in theRMON MIB can be obtained.■ Embedding RMON agents into network devices (such as routers, switches andhubs) directly to make the latter capable of RMON probe functions. When anRMON system operates in this way, the NMS collects network managementinformation by exchanging information with the SNMP agents using the basicSNMP commands. However, this way depends on device resources heavily andan NMS operating in this way can only obtain the information about these fourgroups (instead of all the information in the RMON MIB): alarm group, eventgroup, history group, and statistics group.The 3Com Switch 4210 implements RMON in the second way. With an RMONagent embedded, the Switch 4210 can serve as a network device with the RMONprobe function. Through the RMON-capable SNMP agents running on the switch,an NMS can obtain the information about the total traffic, error statistics andperformance statistics of the network segments to which the ports of the
