Essential SNMP

Receiving Traps

Let’s start by discussing how to deal with incoming traps. Handling incoming traps is the responsibility of the NMS. Some NMSs do as little as display the incoming traps to standard output (stdout). However, an NMS server typically has the ability to react to SNMP traps it receives. For example, when an NMS receives a linkDown trap from a router, it might respond to the event by paging the contact person, displaying a pop-up message on a management console, or forwarding the event to another NMS. This procedure is streamlined in commercial packages but still can be achieved with freely available open source programs.

HP OpenView

OpenView uses three pieces of software to receive and interpret traps:

• ovtrapd (1M)

• xnmtrap

• xnmevents

OpenView’s main trap-handling daemon is called ovtrapd. This program listens for traps generated by devices on the network and hands them off to the Postmaster daemon (pmd ). In turn, pmd triggers what OpenView calls an event. Events can be configured to perform actions ranging from sending a pop-up window to NNM users, forwarding the event to other NMSs, or doing nothing at all. The configuration process uses xnmtrap, the Event Configurations GUI. The xnmevents program displays the events that have arrived, sorting them into user-configurable categories.

OpenView keeps a history of all the traps it has received; to retrieve that history, use the command $OV_BIN/ovdumpevents. Older versions of OpenView kept an event ...