Contemporary Control Systems Compact Managed Switches Software Manual for Web Browser - Manual (Page 34)

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4.4.7.1 Configure Port QoS
When QoS is enabled, Flow Control for each port can be enabled or disabled and two
levels of Port Priority applied. This is the highest method of priority and it is known as
Port QoS. For QoS to be most effective, it is recommended that each port have its flow
control disabled (the default setting). When a port is operating in half-duplex mode, flow
control is accomplished with backpressure. But in full-duplex mode, flow control is
accomplished using the PAUSE protocol. Either method of flow control can affect the
ability of a port to deliver messages and can cause some messages to be delayed.
In the 24-port switch example of Figure 29, Port 2 has been configured for “High” priority
while all other ports are set to “Normal”. But Port 1 (set to “Normal” priority) is the only
port on which Flow Control will function — because only it has had Flow Control enabled.
At the bottom of the screen there are two links to the other types of QoS.
Figure 29 — Configure Port QoS for a 24-port Switch