9-14 CHAPTER 9: STATUS MONITORING AND STATISTICSAn RMON probe, however, autonomously looks at the network onbehalf of the management workstation without affecting thecharacteristics and performance of the network. The probe reports byexception, which means that it only informs the managementworkstation when the network has entered an abnormal state.RMON and theSwitchRMON requires one probe per LAN segment, and stand-alone RMONprobes have traditionally been expensive. Therefore, 3Com’s approachhas been to build an inexpensive RMON probe into the agent of eachSwitch. This allows RMON to be widely deployed around the networkwithout costing more than traditional network management.For example, statistics can be related to individual ports and the Switchcan take autonomous actions such as disabling a port (temporarily orpermanently) if errors on that port exceed a predefined threshold. Also,since a probe must be able to see all traffic, a stand-alone probe mustbe attached to a nonsecure port. Implementing RMON in the Switchmeans that all ports can have security features enabled.RMON Features ofthe SwitchTable 9-5 details the RMON support provided by the Switch 3800.Table 9-5 RMON Support Supplied By the Switch 3800RMON Group Support Supplied by the SwitchStatistics The Switch supports the EtherStats group.History A new or initialized Switch has two History sessions on eachport:n 30-second intervalsn 2-hour intervalsThe Switch can store a maximum of 50 History sessions.Alarms The Switch supports up to 50 alarms. You can enter or deletethese alarms using an RMON management application.Events A new or initialized Switch has events defined for use withthe default alarm system.
