Understanding SNMP traps

About traps

You set traps to inspect the value of MIB variables periodically. Whenever the value of a MIB variable meets the conditions you specify, a trap is sent to the network management stations on the trap host list. The trap host list specifies the network management stations that receive the trap information.

You can set traps on any numeric variable in the MIB. For example, you can set a trap to monitor the disks on an appliance and have the SNMP application on your network management station put a flashing message on your console that tells you that a disk has failed.

Traps are persistent. After you set a trap, it exists across reboots until you specifically remove it or modify it.

Types of traps

There are two types of traps:

Built-in--Built-in traps are predefined in the appliance and are automatically sent to the network management stations on the trap host list if an event occurs. These traps are based on
- RFC 1213, such as coldStart, linkDown, linkUp, and authenticationFailure
- Specific traps defined in the Network Appliance custom MIB, such as diskFailedShutdown, cpuTooBusy, and overTempShutdown.
User-defined--User-defined traps exist only after you create them using the Appliance Manager or the command-line interface.

Where to get more information

See the following RFCs (Requests For Comments) for more information:

RFC 1157--Defines and describes SNMP.
RFC 1213--Defines and describes the SNMP MIB-II specification.