QoS Configuration
rate of interface outputting packet.
20.1.8 Redirection
User can re-specify the packet transmission interface based on the need of its own QoS
strategies.
20.1.9 Priority Mark
Ethernet switch can provide priority mark service for specified packet, which includes: TOS,
DSCP, 802.1p. These priority marks can adapt different QoS model and can be defined in
these different models.
20.1.10 Choose Interface Outputting Queue for
Packet
Ethernet switch can choose corresponding outputting queue for specified packets.
20.1.11 Queue scheduler
It adopts queue scheduler to solve the problem of resource contention of many packets
when network congestion. There are three queue scheduler matchings: Strict-Priority Queue
(PQ), Weighted Round Robin (WRR) and WRR with maximum delay.
(1)PQ
PQ（Priority Queuing）is designed for key service application. Key service possesses an
important feature, that is, require the precedent service to reduce the response delay when
network congestion. Priority queue divides all packets into 4 levels, that is, superior priority,
middle priority, normal priority and inferior priority (3, 2, 1, 0), and their priority levels reduce in
turn.
When queue scheduler, PQ precedently transmits the packets in superior priority
according to the priority level. Transmit packet in inferior priority when the superior one is
empty. Put the key service in the superior one, and non-key service (such as email)in inferior
one to guarantee the packets in superior group can be first transmitted and non-key service
can be transmitted in the spare time.
The shortage of PQ is: when there is network congestion, there are more packets in
superior group for a long time, the packets in inferior priority will wait longer.
(2)WRR
WRR queue scheduler divides a port into 4 or 8 outputting queues (S2926V-O has 4
queues, that is, 3, 2, 1, 0) and each scheduler is in turn to guarantee the service time for each
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