10. 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, and 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.
Priority Mode
There are three priority modes available to specify the priority of packets being serviced.
Those include First-In-First-Out, All-High-Before-Low, and Weight-Round-Robin.
Figure
10-1
First-In-First-Out:
Packets are placed into the queue and serviced in the order they were
received.
All-high-before-low (Strict priority)
：
All packets will be assigned to either high priority
queue (Queue 2) or low priority queue (Queue 1). The packet on the low priority queue
will not be forwarded until the high priority queue is empty.
WRR mode:
There are 4 priority queues for Weighted-and-round-robin (WRR) mode.
When this mode is selected, the traffic will be forwarded according to the number set in
each queue.
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