How to Enable SNMP in Cisco Routers / Switches 

This will help us to monitor our network devices through our networking monitoring tool (cacti,zabbix,observium). Lets learn how to enable the network devices for SNMP. 

1. Telnet to the router/switch
   
   prompt#telnet testrouter
2. Go to the enable mode by specifying the password:
   
   Router>enable
   Password:
   Router#
3. Go into configuration mode:
   
   Router#configure terminal
   Enter configuration commands, one per line. End
   with CNTL/Z.
   Router(config)#
4. Use the command below to add a Read-Only community string:
   
   Router(config)#snmp-server community public RO
   where "public" is the Read-only community string.
5. To add a Read-Write Community string, use the command below:
   
   Router(config)#snmp-server community private RW
   where "private" is the Read-write community string.
6. Exit the configuration mode and save the settings:
   
   Router(config)#exit
   Router#write memory
   Building configuration...
   [OK]
   Router#

To enable SNMP traps, follow the steps below in the Configuration mode of the Router/Switch:

First, set the host to which the traps have to be sent using the folowing command:
snmp-server host <IP Address> version <v1 or 2c> <RO community string>
where,
<IP Address> refers to the IP Address of the device to which the traps have to be sent
<v1 or 2c> refers to the SNMP version
<RO community string> refers to the Read-Only community string
Then, enable SNMP Traps using the command below:
snmp-server enable traps [notification-type] [notification-option]
Ex: snmp-server enable traps config [this will send all configurationnotifications as traps]