The SNMP standard provides a limited number of unsolicited messages (called traps) that are sent from a device to an SNMP application. These messages can be sent by the SNMP agent on the device to notify an SNMP application of a change in status. There are six standard traps (numbered 0 through 5) as well as vendor-provided traps (6):

Trap #

Trap

Description

0

Cold start

The device is rebooting itself and may change its configuration or the SNMP agent's configuration.

1

Warm start

The device is rebooting itself but neither the device's nor the SNMP agent's configuration will change.

2

Link down

One of the communication links for the device is down.

3

Link up

One of the communication links for the device is back up.

4

Authorization failure

The device has received a protocol message that is not properly authenticated.

5

EGP neighbor loss

An EGP neighbor for which the device is an EGP peer is down and the peer relationship no longer exists.

6

Vendor-provided traps

The SNMP specification lets vendors define enterprise specific traps, for example a trap that occurs on a particular vendor’s router.