SNMP is a protocol that allows
management to transmit statistical data over the network to a
central management console. SNMP is a component of the Network
Management Architecture. The Network management Architecture consists
of four major components.
1. Management Station:
The management station is the
network manager's interface into the network system. It has the
programs to manipulate data from and control the network. The
management station also maintains a database of management
information (MIB) extracted from the devices under its
management.
2. Management Agent:
The management agent is the
component that is contained in the devices that are to be
managed. Bridges, routers, hubs, and switches may contain SNMP
agents to allow them to be controlled by the management station.
The management agent responds to the management station in two
ways. First, through polling, the management station requests data from the agent and the agent responds with the requested data.
Trapping is a data gathering method designed to reduce
traffic on the network and processing on the devices being
monitored. Instead of the management station polling the agents
at specific intervals continuously, thresholds (top or bottom
limits) are set on the managed device. If this threshold on the
device is exceeded, the managed device will send an alert
message to the management station. This eliminates the need to
continuously poll all of the managed devices on the network. Trapping is very beneficial on networks with a large number of devices that need to be managed. It reduces the amount of SNMP traffic on the network to provide more bandwidth for data transfer.
3. Management Information Base:
The management information base
has a database structure and is resident on each device that is
managed. The database contains a series of objects, which are
resource data gathered on the managed device. Some of the
categories in the MIB include Port interface data, TCP data, and
ICMP data.
4. Network Management Protocol:
The network management protocol
used is SNMP. SNMP is an application layer protocol designed to
communicate data between the management console and the
management agent. It has three key capabilities. The ability to
GET, the management console retrieving data from the agent, PUT,
the management console setting object values on the agent, and
TRAP, the agent notifying the management console of significant
events.
The key word to remember in Simple
Network Management Protocol is Simple. When SNMP was developed, it was
designed to be a short-term system that would later be replaced. But just like TCP/IP, it has become one of the major standards in Internet-Intranet management configurations.
Over the last few years,
enhancements have been added to SNMP to expand its monitoring and
management capabilities. One of the greatest enhancements to SNMP is
called Remote Monitoring (RMON). RMON extensions to SNMP give the ability to look at the network as a whole as opposed to looking at individual devices.

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