RMON agents gather nine groups of statistics, ten including Token Ring, which are forwarded to a manager on request, usually via SNMP. As summarized in Figure 3-30, RMON1 agents can implement some or all of the following groups:
■ Statistics: Contains statistics such as packets sent, bytes sent, broadcast packets, multicast packets, CRC errors, runts, giants, fragments, jabbers, collisions, and so forth, for each monitored interface on the device.
■ History: Used to store periodic statistical samples for later retrieval.
■ Alarm: Used to set specific thresholds for managed objects and to trigger an event on crossing the threshold (this requires an Events group).
■ Host: Contains statistics associated with each host discovered on the network.
■ Host Top N: Contains statistics for hosts that top a list ordered by one of their observed variables.
■ Matrix: Contains statistics for conversations between sets of two addresses, including the number of packets or bytes exchanged between two hosts.
■ Filters: Contains rules for data packet filters; data packets matched by these rules generate events or are stored locally in a Packet Capture group.
■ Packet Capture: Contains data packets that match rules set in the Filters group.
■ Events: Controls the generation and notification of events from this device.
■ TokenRing: Contains the following Token Ring Extensions:
— Ring Station—Detailed statistics on individual stations
— Ring Station Order—Ordered list of stations currently on the ring
— Ring Station Configuration—Configuration information and insertion/removal data on each station
— Source Routing—Statistics on source routing, such as hop counts Figure 3-30 RMON1 Groups statistics history alarm
Real Time—Current Statistics Statistics Over Time Predetermined Threshold Watch Tracks Individual Host Statistics
5 hostTopN "N" Statistically Most Active Hosts
A< >B—Conversation Statistics
Packet Structure and Content Matching
8 packetCapture Collection for Subsequent Analysis
9 events Reaction to Predetermined Conditions
Token Ring—RMON Extensions
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