QoS Ports and Queues Configuring QoS
page 30-26 OmniSwitch 6800/6850/9000 Network Configuration Guide March 2008
• The weight assigned to a WRR queue designates the number of packets the queue sends out before the
scheduler moves on to the next queue. For example, a queue weight of 10 sends out 10 packets at each
interval.
• The weight assigned to a DRR queue determines the number of bytes that the queue will service. Each
weight value is associated with the following number of bytes: 1=10K, 2=20K, 3=40K, 4=80K,
5=160K, 6=320K, 7=640K, 8=1280K, 9=2560K, 10=5120K, 11=10M, 12=20M, 13=40M, 14=80M,
and 15=160M. For example, if the configured DRR queue weights are 1 1 2 2 3 3 4 4, queues 1/2 will
service up to 10K each, queues 3/4 will service up to 20K each, queues 5/6 will service up to 40K each,
and queues 7/8 will service up to 80K.
• The higher the queue weight assigned to a DRR queue, the higher the percentage of traffic that is
serviced by that queue. For example, a queue with a weight of three will send four times as much traf-
fic as a queue with a weight of one.
The queuing scheme selected is the scheme that is used to shape traffic on destination (egress) ports and is
referred to as the QoS servicing mode for the port. It is possible to configure a default servicing mode that
will apply to all switch ports (see “Setting the Global Default Servicing Mode” on page 30-15) or config-
ure the servicing mode on an individual port basis (see “Configuring the Servicing Mode for a Port” on
page 30-26).
Note that the QoS servicing mode only applies to destination ports because it is at this point where traffic
shaping is effected on the flows. In addition, different ports can use different servicing modes.
Configuring the Servicing Mode for a Port
The qos port servicing mode command is used to configure the queuing scheme for an individual port.
For example, the following command selects the strict priority scheme for port 1/2:
-> qos port 1/2 servicing mode strict-priority
The following command selects the WRR scheme for port 1/8:
-> qos port 1/8 servicing mode wrr
In the above example, a weight for each of the eight WRR queues was not specified; therefore, the default
value of 1 is used for each queue. The following example selects the WRR scheme for port 1/10 and
assigns a weighted value to each queue:
-> qos port 1/10 servicing mode wrr 0 2 3 4 8 1 1 7
To reset the servicing mode for the port back to the global default mode, use the default parameter with
this command and do not specify a queueing scheme. For example,
-> qos port 1/10 servicing mode default
The qos default servicing mode command is used to set the global default queuing scheme that is used
for all ports. See “Setting the Global Default Servicing Mode” on page 30-15 for more information.
Note the following when configuring the port servicing mode:
• The qos port servicing mode command overrides the default servicing mode configured with the qos
default servicing mode command.
• Once the qos port servicing mode command is used on a port, this same command is required to make
any additional mode changes for that port. If the port is changed back to the default servicing mode,
however, this restriction is removed and the qos default servicing mode command is also allowed on
the port.
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