System information

Using SNMP Management Console 337
• List of SNMP Agents pane—displays each agent as an icon. Agents are queried by
request files that define five types of requests: charts, forms, lists, tables, and traps.
When an agent is selected, the requests are displayed in the SNMP Agent Requests
pane.
• SNMP Agent Request pane—SNMP Agent Requests are shown in this pane.
Selecting a chart, form, list, table, or trap will display the associated request output in
the Agent Display pane.
• Agent Display pane—all data is displayed in one window per agent. Each item
(charts, forms, lists, tables, and traps) is selected by the associated tab at the bottom of
the Agent window.
Additionally, SNMP agents can be displayed in map format alongside of Observer Probes.
The map format lets you display graphically (either geographically or topologically) your
network layout, including the positions of SNMP agents and the connections between
them and Observer Probes. You can scan in or draw a map or diagram and place your
servers, hosts, and other SNMP agents in their appropriate locations. SNMP Management
Console includes a set of bitmaps for different devices, or you may add your own bitmaps
for map objects (in Windows BMP format).
SNMP Management Console lets you add, edit, or delete agent entries. When you add a
new agent entry, you must associate a request file with it. Assigning a MIB also makes
available a set of pre-configured menu requests used to poll the agent for data. A request
file defines a set of objects for monitoring from one or more MIB groups. You can remove
request items or create and add new request items using the MIB Editor. See “The MIB
Editor” on page 352.
Functional Overview
SNMP Management Console polls SNMP agents and displays the collected information in
a chart, form, list, or table. To accomplish this, the SNMP Management Console creates
request packets in SNMP format and sends these packets to agents using the UDP protocol
as the carrier. The SNMP packet, often called a PDU (Protocol Data Unit) consists of one
or more SNMP objects.
When SNMP Management Console sends an SNMP packet to an SNMP agent, it either
asks for information about an object (a Get request), or asks to set the value of an object (a
Set request). When the agent receives the SNMP packet, it checks whether the object
exists in the agent's MIB, finds object values, creates a reply packet, and returns the reply
packet to the SNMP Management Console.
Because SNMP uses UDP (User Datagram Protocol) to transfer requests and replies, and
because the UDP protocol does not require the receiving station to acknowledge receipt of
a packet, there is a chance that either the request or reply packet will be lost.
To address this potential problem, SNMP Management Console uses a timeout-retry
mechanism. You can specify the amount of time SNMP Management Console will wait