Qos; Port - RACOM RAy3-11 User Manual

5.5.3. QoS

Quality of Service (QoS) is the ability to provide different priorities to different applications, users, or
data flows, or to guarantee a certain level of performance to a data flow. QoS using 802.1p and DSCP
are implemented.
The ingress block has the task of determining the priority of each frame to be used for the internal
Queue Controller (QPri) as well as the priority assigned to the frame (FPri) if the frame egresses the
switch tagged. The classification as to if the frame is discard eligible (Yellow) is also determined. The
Ingress block does not perform the QoS switching policy, which is the task of the Queue Controller.
Instead, it has the job of determining the QPri and FPri assigned to each frame for the Queue Controller
and Egress block.

5.5.3.1. Port

Port based QoS parameters makes it possible to control QoS based on the ingress port.
Every frame entering the switch gets two priority values assigned to it. One priority value is used inside
the switch only to determine which output queue the frame is to be mapped into. This is called QPri for
queue priority. The other priority value is used outside the switch only to mark the frame's IEEE PCP
bits if the frame egresses a port tagged. This is called FPri for frame priority. A third parameter, called
Yellow, is also assigned to the frame. If Yellow=1 the frame is considered eligible for discard if congestion
warrants it.
The initial QPri, FPri and Yellow values are assigned differently to various frame types. Some frames
are assigned more than one set of QPri, FPri and Yellow values. For example, an IEEE tagged IPv4
frame will get a set of values from the IEEE tag, another set from the IPv4 header and another set from
the port. Some applications require that the port's default priority be used regardless of the contents
of the frame. The Initial priority parameter selects this default priority.
Fig. 5.25: Menu Switch settings > QoS > Port
Update DSCP
If the parameter is enabled, the DSCP field in frames that egress this port is updated.
Default frame priority
All ingressing frames are assigned a default FPri (frame priority) and QPri (queue priority). The
default value for Yellow is zero (i.e. the frame is not discarded eligible).
Default queue priority
All ingressing frames are assigned a default FPri (frame priority) and QPri (queue priority).
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