HP StorageWorks 2/140 FW 08.01.00 McDATA E/OS SNMP Support Manual (620-000131- - Page 15

Introduction to SNMP 1 • Set-A manager can change the variables in the agent by sending this single command. This command is used to change the management data. • GetBulk-This command is used by the manager to retrieve voluminous data from a large table in the agent. • Trap-An Agent uses this command to inform the manager about some unusual events. Refer to Traps and Their Purpose on page 1-9. • Inform- This command is used by a manager to send alert to another manager. NMS GetRequest PDU GetResponse PDU Get Values Switch NMS SetRequest PDU SetResponse PDU Set Values Figure 1-1 SNMP Commands and Responses GetNextRequest PDU GetResponse PDU Get Next Values Switch Trap PDU Send Trap Why Variables exist In a Managed Device Variables are the means by which devices like switches and directors keep track of and control their performance apart from providing access about their performance to 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 the network managers to have access to some of the same variables for network management. For purposes of the following explanation, an object is a data variable that represents an attribute of a managed device. How SNMP Changes Variables in a Managed Device An agent has an interface to the actual object being managed (Figure 1-2 on page 1-4). The agent understands SNMP and translates between the manager and the object. Each SNMP element manages specific objects. Each object has an identifier, OID. Objects may be Network Management using SNMP 1-3