Configuring Quality of Service
December 2005 © Foundry Networks, Inc. 13 - 13
Syntax: qos name <old-name> <new-name>
The <old-name> parameter specifies the name of the queue before the change.
The <new-name> parameter specifies the new name of the queue. You can specify an alphanumeric string up to
32 characters long.
Changing the Minimum Bandwidth Percentages of the Queues
If you are using the weighted round robin mechanism instead of the strict mechanism, you can change the weights
for each queue by changing the minimum percentage of bandwidth you want each queue to guarantee for its
traffic.
By default, the eight QoS queues on FESX, FSX, and FWSX devices receive the following minimum guaranteed
percentages of a port’s total bandwidth
When the queuing method is weighted round robin, the software internally translates the percentages into
weights. The weight associated with each queue controls how many packets are processed for the queue at a
given stage of a cycle through the weighted round robin algorithm.
NOTE: Queue cycles on the FESX, FSX, and FWSX are based on bytes. These devices service a given number
of bytes (based on the weight) in each queue cycle. FES and BI/FI queue cycles are based on packets.
The bytes-based scheme is more accurate compared to a packets-based scheme if packets vary greatly in size.
The bandwidth allocated to each queue is based on the relative weights of the queues. You can change the
bandwidth percentages allocated to the queues by changing the weights of the queues.
There is no minimum bandwidth requirement for a given queue. For example, queue qosp3 is not required to have
at least 50% of the bandwidth.
Table 13.9: Default Minimum Bandwidth Percentages on FESX, FSX, and FWSX Devices
Queue Default Minimum Percentage of
Bandwidth
qosp7 75%
qosp6 7%
qosp5 3%
qosp4 3%
qosp3 3%
qosp2 3%
qosp1 3%
qosp0 3%
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