D-Link DGS-1510 Series Reference Manual page 492

DGS-1510 Series Gigabit Ethernet SmartPro Switch CLI Reference Guide
wdrr
Default
The default queue scheduling algorithm is WRR.
Command Mode
Interface Configuration Mode.
Command Default Level
Level: 12.
Usage Guideline
Specify schedule algorithms to WRR, SP, RR or WDRR for the output queue. By default, the output
queue scheduling algorithm is WRR. WDRR operates by serving an accumulated set of backlogged
credits in the transmit queue in a round robin order. Initially, each queue sets its credit counter to a
configurable quantum value. Every time a packet from a CoS queue is sent, the size of the packet is
subtracted from the corresponding credit counter and the service right is turned over to the next lower
CoS queue. When the credit counter drops below 0, the queue is no longer serviced until its credits
are replenished. When the credit counters of all CoS queues reaches 0, the credit counters will be
replenished at that time.
All packets are serviced until their credit counter is zero or negative and the last packet is transmitted
completely. When this condition happens, the credits are replenished. When the credits are
replenished, a quantum of credits are added to each CoS queue credit counter. The quantum for each
CoS queue may be different based on the user configuration.
To set a CoS queue in the strict priority mode, any higher priority CoS queue must also be in the strict
priority mode.
WRR operates by transmitting permitted packets into the transmit queue in a round robin order.
Initially, each queue sets its weight to a configurable weighting. Every time a packet from a higher
priority CoS queue is sent, the corresponding weight is subtracted by 1, and the packet in the next
lower CoS queue will be serviced. When the weight of a CoS queue reaches zero, the queue will not
be serviced until its weight is replenished. When weights of all CoS queues reach 0, the weights get
replenished at a time.
Example
This example shows how to configure the queue scheduling algorithm to the strict priority mode.
Switch# configure terminal
Switch(config)# interface eth3/0/1
Switch(config-if)# mls qos scheduler sp
Switch(config-if)#
56-12 mls qos trust
This command is used to configure the trust state of a port to trust either the CoS field or the DSCP
field of the arriving packet for subsequent QoS operation. Use the no form of this command to revert
to the default setting.
mls qos trust {cos | dscp}
no mls qos trust
Parameters
cos
Specifies the queues of all ports in the frame length (quantum)
weighted deficit round-robin scheduling. If the weight of a queue be
configured to zero, the queue is in the SP scheduling mode.
Specifies that the CoS bits of the arriving packets are trusted for
subsequent QoS operations.
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