Configuring Quality of Service 67911Configuring Quality of ServiceOverviewThe Quality of Service menu page contains links to the following pages:• Differentiated Services• Class of Service• Auto VoIPIn a typical switch, each physical port consists of one or more queues for transmitting packets on theattached network. Multiple queues per port are often provided to give preference to certain packetsover others based on user-defined criteria. When a packet is queued for transmission in a port, therate at which it is serviced depends on how the queue is configured and possibly the amount oftraffic present in the other queues of the port. If a delay is necessary, packets get held in the queueuntil the scheduler authorizes the queue for transmission. As queues become full, packets have noplace to be held for transmission and get dropped by the switch.QoS is a means of providing consistent, predictable data delivery by distinguishing between packetsthat have strict timing requirements from those that are more tolerant of delay. Packets with stricttiming requirements are given “special treatment” in a QoS capable network. With this in mind, allelements of the network must be QoS-capable. The presence of at least one node which is not QoS-capable creates a deficiency in the network path and the performance of the entire packet flow iscompromised.
