User Guide    784
  RMON
4 
RMON
RMON (Remote Network Monitoring) together with the SNMP system allows the network 
manager to monitor remote network devices efficiently. RMON reduces traffic flow 
between the NMS and managed devices, which is convenient to manage large networks.
RMON includes two parts: the NMS and the Agents running on every network device. The 
NMS is usually a host that runs the management software to manage Agents of network 
devices. The Agent is usually a switch or router that collects traffic statistics (such as the 
total number of packets on a network segment during a certain time period, or total number 
of correct packets that are sent to a host). Based on SNMP protocol, the NMS collects 
network data by communicating with Agents. However, the NMS cannot obtain every 
datum of RMON MIB because the device resources are limited. Generally, the NMS can only 
get information of the following four groups: Statistics, History, Event and Alarm.
 ■
Statistics: Collects Ethernet statistics (like the total received bytes, the total number of 
broadcast packets, and the total number of packets with specified size) on an interface.
 ■
History: Collects a history group of statistics on Ethernet ports for a specified polling 
interval.
 ■
Event: Specifies the action to be taken when an event is triggered by an alarm. The 
action can be to generate a log entry or an SNMP trap.
 ■
Alarm: Monitors a specific MIB object for a specified interval, and triggers an event at a 
specified value (rising threshold or falling threshold).
Downloaded from ManualsNet.com search engine