Traps and Syslog monitoring is optional. Configuring Traps on the device will not extend any additional polling to the device.
Traps are used for Out of Band Polling for when you need to know about a Device Status change. Traps works best for when you need to know about a change right now and work best for when there is a Device Configuration Change, Routing Change, or a Port Status change.
The majority of customers use the Traps or Syslog viewer for Alerting. Long term, 1 year +, Trap and Syslog Storage they use Kiwi Syslog to remove any performance impact from the SQL Server.
Unless you have an application that sends traps through RHEL you might be better off using the rsyslog function which will provide you the option of what logs and events you want to forward where...
Thank you for answers.
Could you give me an example where it's usefull to use them?
e.g. : If I want to get an alert when there is a deadlock on one DB, should I use them ?
Or maybe, should I use Udnp for this ?