"Utilization" is the percentage of a network's bandwidth that is currently being consumed by network traffic. Consistently high (>40%) utilization indicates points of network slowdown (or failure) and a need for changes or upgrades in your network infrastructure. Each vertical bar represents the highest utilization on a port, and can be either transmitted (Tx) traffic or received (Rx) traffic during the last five-second interval. That is, if the highest utilization on a port is received (Rx) traffic, then the graph shows the amount of bandwidth currently used to receive traffic. If the highest utilization on a port is transmitted (Tx) traffic, then the converse is true. For an example of how utilization is calculated, see Utilization Calculation, below.
The bar graph is designed to help you quickly identify which port(s) are the source of excessive traffic. The Legend in the Status/Overview screen identifies traffic types and their associated colors on the bar graph:
To display a breakdown of numeric utilization values and the speed (bandwidth) setting for a port that is "up" status, click on the bar over that port in the port utilization graph.
The purpose of knowing utilization is to know whether a link in the network is overloaded. Thus, the bar graph for a port shows utilization for the busiest half-link (Rx or Tx) on the port. For example, using a port configured for 100Mbps, full-duplex, if the port was transmitting at 35% utilization on one half-link and receiving at 10% on the other half-link, the port would show a 35% utilization.
Utilization is calculated by the formula
Thus, on a 10Mbps half-duplex port, a 3-second measurement of 6,000,000 bits would indicate a 20% utilization of the port.
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