Understanding the network.pdf - Back to Home

throughput over time, instead of single utilization value. Therefore, the peak and
low utilization measurements are typically expressed through a "utilization versus
time" graph that plots the network segments utilization over the duration of the
traffic sample period.
Because all three of these measurements are based on traffic samples versus
long-term traffic monitoring that, in order to get a good determination of the
network segments actual average, peak, and low utilization measurements, you
need to perform several network segment traffic collections. You should perform
them during different times of the day, over an extended calendar period, and then
developing your own histograph comparing the results.
As you begin to plot your network's utilization, you will begin to see consistent
utilization trends over time.
NOTE
The first value is the composite bandwidth. The composite bandwidth is the amount
of available segment bandwidth capacity that is being used for data transmission.
The composite value is determined by examining the frame/second rate of the
traffic on the network segment, and calculating utilization based on the mean
average packet size and transmission rate. Actually, it consists of three values:
• The mean average utilization rate
• The peak utilization usage rate
• The low utilization usage rate
Each of these values (mean/peak/low) is derived by taking repeated FPS/PPS
measurements over a period of time.
NOTE
Any unexplained utilization shifts typically indicate a hardware or software
component problem on the segment. This should be investigated to determine the
cause of the problem.
After you start to develop a utilization profile, you then want to compare your actual
utilization measurements to what the expected operational "norms" are in order to
determine if you need to make any network backbone or user segment topology
changes to improve performance. When doing so, keep in mind that average, peak,