SNMP Get requests (or polling) and SNMP Traps communicate data using numeric OIDs (Object IDentifiers). The OIDs are translated from numbers into textual strings for easier reading and understanding by using MIB (Management Information Base) files.
Manufacturers have to conform to a set of standards for OIDs to work correctly - as a result, common SNMP OIDs should be translated on your Opsview Monitor Master and Opsview Monitor Slave Nodes without any extra configuration.
However, many SNMP capable devices have specific attributes that are unique to them and as such may need additional MIBs installed on the Opsview Monitor systems to be able to translate the OIDs.
Some of these additional MIBs may be available through your normal package repository (for example, for Debian and Ubuntu) on each Opsview Monitor server.
Other MIBs will need to be obtained from your device manufacturer and installed onto each of the Opsview Monitor servers. You can either use one of your distributions preexisting MIB directories, or you could place the MIB files into `/usr/local/nagios/snmp/load' and amend your /etc/snmp/snmp.conf file to include a lines similar to:
mibdirs +/usr/local/nagios/snmp/load mibs +ALL
This will add the directory to the MIB search path your SNMP utilities use.
You can see which directories are currently used on your Opsview Monitor system by using a command similar to
snmpget -v2c -D get_mib_directory -c <community string> <hostname> SNMPv2-MIB::sysDescr.0