Edimax Technology Edimax 24 10/100TX + 2 10/100/1000T/Mini-GBIC Combo Web Smart Switch ES-5226RS - Manual (Page 37)

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QoS Setting
Here you can configure QoS policy priority mode and CoS (Class of Service)
configuration. QoS (Quality of Service) refers to mechanisms in the network
software that make the actual determination of which packets have priority. CoS
refers to feature sets, or groups of services, that are assigned to users based on
company policy. If a feature set includes priority transmission, then CoS winds up
being implemented in QoS functions within the routers and switches in the
network. In an enterprise network, class of service (CoS) differentiates
high-priority traffic from lower-priority traffic. Tags may be added to the packets to
identify such classes, but they do not guarantee delivery as do quality of service
(QoS) functions, which are implemented in the network devices.