Functioning of ifSpeed, Utilization and Throughput.

Content

We set the speed of the interface subelement by the value that is returned from the ifSpeed OID during inventory. We can also evaluate the speed and classify them as either high or low speed interfaces.

Then we use this speed property or even the current ifSpeed OID value in our formulas.Utilization uses speed in its calculation.

For utilization we take Total Passed / Total Possible * 100 to make it a %. In other words we get the volume of data passed since last poll. (delta of ifInOctets) * 8 (to convert it to bits) divided by delta of time since last poll. (converts to bits pers second bps) divided by ifSpeed * 100 for a percentage.

(((ifInOctets * 8) / 900) / ifSpeed) * 100 = Interface Utilization %.

For Throughput we measure the volume of data passed over time since last poll. So like in the example above we will use ifInOctets.

((ifInOctets * 8) / 900) = bits per second (Throughput)

For throughput we measure the volume of data passed over the time since last poll, and we then break that down to bits per second ( I believe) so we can say that over the last poll period you averaged 7 Mbps (Megabits per second) through this 10 Mbps interface. So that would also break down to 70% utilized and 63,000 bits or a total volume of 7.8MBytes passed over the 15 minutes.

(These are not exact numbers just for an example)

Since we're using sysUpTime.0 (the number of hundreths of a second the router has been up) we actually are calculating the following:

PollTime.1 - PollTime.0 / 100 = Seconds elapsed
PollValue.1 - PollValue.0 = Bytes passed

So we take the bytes passed and divide by the seconds elapsed to get a Bytes per second. We convert bytes to bits (multiply by 8)

Now we have the bits per second.

Take the bits per second and divide by the property.ifSpeed and you have the ratio of utilization, We then multiply by 100 to get the percent utilization.