3Com Switch 7750 Configuration Guide Guide

65
RMON CONFIGURATION
Introduction to RMON 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 internetworks.
Working Mechanism of
RMON
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 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
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.
The Switch 7750 Family implements RMON in the second way. With the
embedded RMON agent, the Switch 7750 Family can serve as a network device
with the RMON probe function. Through the RMON-capable SNMP agents
running on the Ethernet switch, 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.