Cisco IOS Cookbook, 2nd Edition

Enabling SNMP Traps and Informs

Problem

You want the router to generate SNMP traps or informs in response to various network events.

Solution

The following configuration commands will enable your router to send unsolicited SNMP traps to a network management server:

Router#configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#snmp-server enable traps
Router(config)#snmp-server host 172.25.1.1 ORATRAP config entity envmon hsrp
Router(config)#snmp-server host nms.oreilly.com ORATRAP bgp snmp envmon
Router(config)#end
Router#

Notice that the snmp-server host command will accept either an IP address or a hostname.

Beginning with SNMP Version 2c, Cisco routers also support SNMP informs. To enable SNMP informs, use the following commands:

Router#configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)#snmp-server enable informs
Router(config)#snmp-server host 172.25.1.1 informs version 2c ORATRAP snmp envmon
Router(config)#end
Router#

Discussion

SNMP Traps originate from the router’s agent and are sent via UDP (port 162) to the network management station (NMS). Unlike the information that the router sends to the NMS in response to an SNMP poll, a trap is unsolicited. The router’s agent decides that something important has happened, and that it needs to tell the NMS about it. Before the router agent can send traps, you must enable global trap support (see Table 17-4) and configure the trap host.

SNMP traps are one of the ...