Tips on setting up MIB data collections. How is it possible to monitor performance data on a router? For example, CPU usage, Memory usage, Interface utilization, backplane utilization, or Frame relay circuit utilization?
Study the MIBs that are provided on the devices by the SNMP agent to find out what data is available there. The MIBs are built by the provider of the SNMP agent on the device, and therefore can include any data they choose, and arrange it in any order. Some MIB data is common to most SNMP agents in the "MIB-II" tree. This is mostly information about the interfaces on the device.
Pay attention to the data types. The snmpCollect tool will record counter data, such as used in interface traffic, as the rate change over the sampling interval. So if data is collected every minute and the value changed from 1000 to 3000 over a minute, snmpCollect would report that as 2000 per minute.
Utilization is a generally not available value. However it can be calculated from data that is available in MIBs. For example, link utilization can be calculated by taking the ifInOctets and ifOutOctets values from the MIB for an interface, subtract them, and divide them by the ifSpeed value for the MIB. But remember that these traffic values are counters and are reported as octets over the sampling period. So also include the sample interval in the calculation. If sampling once per minute, divide the result by 60 because the sample of ifInOctets and ifOutOctets is reported in octets per minute while the ifSpeed is reported in octets per second.
MIB calculations are stored in the "/usr/OV/conf/mibExpr.conf" file and then can be selected when setting up a data collection.
When selecting MIB files to load into NetView, be sure to choose SNMPv1 instead of SNMPv2, since the snmpCollect tool does not support SNMPv2. However, on NetView 7.1.5 there is a new SNMP data collector which supports both SNMPv1 and SNMPv2.