Novell NETWARE 6-DOCUMENTATION Manual page 2052

Monitoring the Server Using SNMP
How SNMP Works
You can monitor your server in real time by using the Simple Network
Management Protocol (SNMP). SNMP is a protocol used to exchange data
about network activity. With SNMP, data travels between a managed device
and a network management station (NMS) where users remotely manage the
network.
A managed device is anything that runs SNMP (for example, hosts or routers).
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Your Novell Enterprise Web Server is a managed device. An NMS is usually
a powerful workstation with one or more network management applications
installed. A network management application graphically shows information
about managed devices (which device is up or down, which and how many
error messages were received, etc.).
Every managed device contains an SNMP agent that gathers information
regarding the network activity of the device. This agent is known as the
subagent. Each Web server has a subagent.
Another SNMP agent exchanges information between the subagent and NMS.
This agent is called the master agent. A master agent runs on the same host
computer as the subagents to which it talks. You can have multiple subagents
installed on a host machine. All of these subagents can communicate with the
master agent.
Values for various variables that can be queried are kept on the managed
device and reported to the NMS as necessary. Each variable is known as a
managed object, which is anything the agent can access and send to the NMS.
All managed objects are defined in a management information base (MIB),
which is a database with a tree-like hierarchy.
SNMP exchanges network information in the form of protocol data units
(PDUs). PDUs contain information about various variables stored on the
managed device. These variables, also known as managed objects, have
values and titles that are reported to the NMS as necessary. Communication
between an NMS and managed device can take place in one of two forms:
NMS-initiated and managed-device-initiated.
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