D-Link xStack DGS-3610 Series Configuration Manual page 628

Chapter 45 QOS Configuration
45.1.2.2 Policing
The Policing action happens after the data classifying is completed. It is used to constrain
the transmission bandwidth occupied by the classified dataflow. The Policing action will
check every packet in the classified dataflow. If the packet is occupying more bandwidth as
allowed by the police that applies on that dataflow, the packet will be treated specially, either
to be discarded or assigned with another DSCP value.
In the QoS processing flow, the Policing action is optional. If no Policing action is enabled,
the DSCP value of packets in the classified data flow will remain unchanged, and no packet
will be discarded before the packet is sent for the Marking action.
45.1.2.3 Marking
After the Classifying and Policing actions, the Marking action will write the QoS information
for the packet to ensure that the DSCP value of the classified packet can be transferred to
the next hop device in the network. Here, the QoS ACLs can be used to change the QoS
information of the packet, or the QoS information is reserved in the Trust mode. For example,
the Trust DSCP can be selected to reserve the DSCP information in the IP packet header.
45.1.2.4 Queuing
The Queuing action is responsible for transferring the packets in the dataflow to an output
queue of the port. The packets in different output queues will have transmission service
policies of different levels and qualities.
Each port has 8 output queues. The two mapping tables DSCP-to-CoS Map and
Cos-to-Queue Map configured on the device convert the DSCP value of the packet into
output queue number so as to determine the specific output queue to transfer the packets
into.
45.1.2.5 Scheduling
The Scheduling action is the last cycle in the QoS process. After the packets are transferred
into different output queues of the port, the device works with WRR or another algorithm to
transmit the packets in those 8 queues.
It is possible to set the weight in the WRR algorithm to configure the number of packets to be
transmitted in every cycle of packet output, thus affecting the transmission bandwidth.
Alternatively, it is possible to set the weight in the DRR algorithm to configure the number of
packet bytes to be transmitted in every cycle of packet output, thus affecting the
transmission bandwidth.
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DGS-3610 Series Configuration Guide