3Com 9100 manual Rmon Group Support Supplied by the Switch Statistics, History, Alarms, Events

122CHAPTER 8: STATUS MONITORING AND STATISTICS

An RMON probe, however, autonomously looks at the network on behalf of the management workstation without affecting the characteristics and performance of the network. The probe reports by exception, which means that it only informs the management workstation when the network has entered an abnormal state.

RMON and the RMON requires one probe per LAN segment, and stand-alone RMON Switch probes have traditionally been expensive. Therefore, 3Com’s approach

has been to build an inexpensive RMON probe into the agent of each switch. This allows RMON to be widely deployed around the network without costing more than traditional network management.

For example, statistics can be related to individual ports and the switch can take autonomous actions such as disabling a port (temporarily or permanently) if errors on that port exceed a predefined threshold. Also, since a probe must be able to see all traffic, a stand-alone probe must be attached to a nonsecure port. Implementing RMON in the switch means that all ports can have security features enabled.

RMON Features of Table 35 details the RMON support provided by the Switch 9100. the Switch

Table 35 RMON Support Supplied By the Switch 9100

RMON Group	Support Supplied by the Switch
Statistics	The switch supports the EtherStats group.
History	A new or initialized switch has two History sessions on each
	port:
	■	30-second intervals
	■	2-hour intervals
	The switch can store a maximum of 50 History sessions.
Alarms	The switch supports up to 50 alarms. You can enter or delete
	these alarms using an RMON management application.
Events	A new or initialized switch has events defined for use with the
	default alarm system.