3. SNMP NETWORK MANAGEMENT
The Simple Network Management Protocol (SNMP) is an application-layer protocol that
facilitates the exchange of management information between network devices. It is part of
the TCP/IP protocol suite. SNMP enables network administrators to manage network
performance, find and solve network problems, and plan for network growth.
SNMP consists following key components,
Managed device is a network node that contains SNMP agent. Managed devices collect
and store management information and make this information available to NMS using
SNMP. Managed device can be switches/Hub, etc.
MIB (Management Information Base) define the complete manageable entries of the
managed device. These MIB entries can be either read-only or read-write. For example, the
System Version is read-only variables. The Port State Enable or Disable is a read-write
variable and a network administrator can not only read but also set its value remotely.
SNMP Agent is a management module resides in the managed device that responds to the
SNMP Manager request.
SNMP Manager/NMS executes applications that monitor and control managed devices.
NMS provide the bulk of the processing and memory resources required for the complete
network management. SNMP Manager often composed by desktop computer/work station
and software program such like HP OpenView.
Totally 4 types of operations are used between SNMP Agent & Manager to change the MIB
information. These 4 operations all use the UDP/IP protocol to exchange packets.
GET: This command is used by an SNMP Manager to monitor managed devices. The
SNMP Manager examines different variables that are maintained by managed devices.
GET Next: This command provides traversal operation and is used by the SNMP Manager
to sequentially gather information in variable tables, such as a routing table.
SET: This command is used by an SNMP Manager to control managed devices. The NMS
changes the values of variables stored within managed devices.
Trap: Trap is used by the managed device to report asynchronously a specified event to the
SNMP Manager. When certain types of events occur, a managed device will send a trap to
alert the SNMP Manager.
The system built-in management module also supports SNMP management. User must
install the MIB file before using the SNMP based network management system. The MIB file
is on a disc or diskette that accompanies the system. The file name extension is .mib, which
SNMP based compiler can read.
Please refer to the appropriate documentation for the instructions of installing the system
private MIB.
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