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Introduction to RMON
Working Mechanism of
RMON
Commonly Used RMON
Groups
RMON C
ONFIGURATION
Remote monitoring (RMON) is a kind of management information base (MIB) defined
by Internet Engineering Task Force (IETF) and is a most important enhancement made
to MIB II standards. RMON is mainly used to monitor the data traffic across a network
segment or even the entire network, and is currently a commonly used network
management standard.
An RMON system comprises of two parts: the network management station (NMS)
and the agents running on each network device. RMON agents operate on network
monitors or network probes to collect and keep track of the statistics of the traffic
across the network segments to which their ports connect such as the total number
of the packets on a network segment in a specific period of time and the total
number of packets that are sent to a specific host successfully.
RMON is fully based on simple network management protocol (SNMP) architecture. It
is compatible with the current SNMP, so that you can implement RMON without
modifying SNMP. RMON enables SNMP to monitor remote network devices more
effectively and actively, thus providing a satisfactory means of monitoring the
operation of the subnet. With RMON, the communication traffic between NMS and
agents is reduced, thus facilitating the management of large-scale internets.
RMON allows multiple monitors. It collects data in one of the following two ways:
Using the dedicated RMON probe. When an ROM system operates in this way, the
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NMS directly obtains management information from the RMON probes and
controls the network resources. In this case, all information in the RMON MIB can
be obtained.
Embedding RMON agents into network devices (such as routers, switches and
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hubs) directly to make the latter capable of RMON probe functions. When an
RMON system operates in this way, the NMS collects network management
information by exchanging information with the SNMP agents using the basic
SNMP commands. However, this way depends on device resources heavily and an
NMS operating in this way can only obtain four groups of information (instead of
all the information in the RMON MIB). The four groups are alarm group, event
group, history group and statistics group.
An S3100 series switch implements RMON in the second way. Through the
RMON-capable SNMP agents running on the network monitors, an NMS can obtain
the information about the total traffic, error statistics and performance statistics of
the network segments to which the ports of the managed network devices are
connected. Thus, the NMS can further manage the networks.
Event group
The event group is used to define the indexes of events and the processing methods
of the events. The events defined in an event group are mainly used in alarm group
and extended alarm group to trigger alarms.