How do I collect bandwidth utilization data on remote devices/switches/servers?

Question

How do I collect bandwidth usage/utilzation on devices/switches. From what I understand there are systems that do something like this. They seem to all have snmp in common.<

Answer 1

On pure SNMP point of view, there is a Management Information Base (MIB) on your SNMP device.

This base is a kind of tree where datas are named using Object IDentifiers (OIDs). One of these datas is a counter called "ifInOctets" in the interface group of MIBII, it represents the number of "In" octets on one of the interface of the SNMP device, another one ("ifOutOctets") represent the number of "Out" octets. You will find in your favorite language (PHP) a way to get these two counters. You also have the information of the interface speed in "ifSpeed" counter. With NET-SNMP tools installed (on Linux or Microsoft) you can get the information with "snmpget"

snmpget -v 1 -c public localhost ifInOctets.65539
IF-MIB::ifInOctets.65539 = Counter32: 82929271

Imagine you take 2 values of "ifInOctets" I1 and I2 with an interval of S seconds. You can compute your "In" bandith.

"In" Bandwith usage in % = (((I2-I1) * 8)*100) / (ifSpeed * S)

If you just want to have a nice graph of the bandwith usage of your device just try MRTG tool.

Best regards.

JP