SNMP Management 11-1
11
SNMP Management

11.1 THE SNMP PROTOCOL

SNMP (Simple Network Management Protocol) is a communication protocol for managing
devices or other elements on a network. Network equipment commonly managed with SNMP
includes hubs, switches, routers, and host computers. SNMP is typically used to configure these
types of devices for proper operation in their network environment, as well as to monitor them to
evaluate their performance and detect potential problems.
Managed entities supporting SNMP typically contain software, which runs locally on the device
and is referred to as an agent. The software in the switch functions as an agent, monitoring and
controlling the functionality of the switch.
A defined set of variables, referred to as managed objects, is maintained by the agent and used to
manage the device. These objects are defined in a Management Information Base (MIB) which
allows for a standard presentation of the information controlled by the agent over the network.
The software used to access the information maintained by the SNMP agents across a network is
referred to as the SNMP Manager, and typically runs on a workstation.
The SNMP manager software uses a MIB specification, equivalent to that which the agent
maintains, to read and write objects controlled by the agent for purposes of configuring and
monitoring the device. SNMP defines the format of the MIB specifications and the protocol used
to access this information.
There are three main operations defined in SNMP:
•GET operations read information from the managed device, such as those used to obtain status
or statistical data.
•SET operations change a functional parameter on the device, such as those used to configure Port
Speed or to initiate a software download. GET and S ET operations are initiated only by the
manager software, and result in a response by the agent.
•TRAP operations allow the agent to send an unsolicited message to the manager. This operation
is typically used as an alert of a potential problem or a change of status with the device. The Trap
Destination parameter in the SNMP Configuration Menu is used to configure the IP addresses
of the SNMP Manager to which switch trap messages are sent.