5-26 C HAPTER 5: A DVANCED M ANAGEMENTRMON and the SwitchRMON requires one probe per LAN segment, andstand-alone RMON probes have traditionally beenexpensive. Therefore, 3Com’s approach has been tobuild an inexpensive RMON probe into the Smart-Agent of each Switch. This allows RMON to bewidely deployed around the network without cost-ing more than traditional network management.A problem with stand-alone RMON probes is thatthey are passive; able to monitor and report, butnothing more. Placing probe functionality inside thenetwork device allows integration of RMON withnormal device management to allow proactive man-agement.For example, statistics can be related to individualports and the Switch can take autonomous actionssuch as disabling a port (temporarily or permanently)if errors on that port exceed a pre-defined thresh-old. Also, since a probe needs to be able to see alltraffic, a stand-alone probe has to be attached to anon-secure port. Implementing RMON in the Switchmeans all ports can have security features enabled.RMON Features of the SwitchTable 5-2 details the RMON support provided bythe Switch.Table 5-2 RMON support supplied by the SwitchRMON Group Support supplied by the SwitchStatistics A new or initialized Switch has one Statistics ses-sion per port/VLAN.History A new or initialized Switch has three History ses-sions on the 100BASE-TX port, backbone portand Default VLAN:n 60-second intervals, 120 historical samplesstoredn 30-second intervals, 120 historical samplesstoredn 30-minute intervals, 96 historical samplesstoredAlarms Although up to 700 alarms can be defined forthe Switch, a new or initialized Switch has fouralarms defined for each port:n Bandwidth usedn Broadcast bandwidth usedn Percentage of packets forwardedn Errors per 10,000 packetsYou can modify these alarms using an RMONmanagement application, but you cannot createor delete them.For more information about the alarms setup onthe Switch, refer to “About Alarm Actions” onpage 5-28 and “About Default Alarm Settings”on page 5-29.
