FW V06.XX/HAFM SW V08.02.00 HP StorageWorks SNMP Reference for Directors and Edge Switches (AA-RQ7BE-TE, July 2004)

Introduction to SNMP
17SNMP Reference for Directors and Edge Switches
SNMP Commands
A manager requests information from an agent by sending a single command, the
Get command. The Get command also has a variation (GetNextRequest)
that permits more efficient operation:
■ GetRequest – Requests the value of a specified variable on the agent. This
command is used to retrieve management data.
■ GetNextRequest – Requests the value of the next variable after the one
specified in the command. This command is used to retrieve lists and tables of
management data.
An agent responds to a request by sending a single command, the GetResponse
command. This command contains the requested information.
A manager changes information (variables) in the agent by sending a single
command, the SetRequest command. This command is used to manipulate
management data.
A trap is used by an agent to report extraordinary events. Refer to “Traps and
Their Purpose” on page 19. Figure 1 illustrates SNMP commands and responses:
Figure 1: SNMP commands and responses
Why Variables Exist in a Managed Device
Variables are the means by which a Director or Edge Switch (and other devices)
keep track of their performance, control their own performance, and provide
access to information about their performance for network managers. A simple
example of a variable’s use is to set a port offline and turn the port back on. Some
variables just hold values that indicate status (for example, error counts). SNMP
allows network managers to have access to some of the same variables for
network management.