Chapter 6 QoS
QoS (Quality of Service) functions to provide different quality of service for various network
applications and requirements and optimize the bandwidth resource distribution so as to provide a
network service experience of a better quality.
QoS
This switch classifies the ingress packets, maps the packets to four different priority queues and
then forwards the packets according to Strict-Priority scheduling algorithms to implement QoS
function.
Figure 6-1 QoS function
Traffic classification: Identifies packets conforming to certain characters according to certain
rules.
Map: This switch supports four priority queues. The priority queues are labeled as 1(Lowest),
2(Normal), 3(Medium) and 4(Highest), among them the bigger the value, the higher the
priority. The ingress packets are mapped to four different priority queues based on the QoS
modes. This switch implements two QoS modes based on port and on 802.1P.
Queue scheduling algorithm: When the network is congested, the problem that many packets
compete for resources must be solved, usually in the way of queue scheduling. In both
port-based and 802.1P QoS modes, this switch adopts Strict-Priority scheduling algorithm. In
Strict-Priority scheduling algorithm, the queue with higher priority will occupy the whole
bandwidth. Packets in the queue with lower priority are sent only when the queue with higher
priority is empty.
QoS Mode
This switch implements two QoS modes based on port and on 802.1P. By default, the QoS mode
based on port is enabled and the other one is optional.
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