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Catalyst 6500 Series Switch Command Reference—Release7.6
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Chapter2 Catalyst 6500 Series Switch and ROM Monitor Commands
set qos wrr
set qos wrr
To specify the weights that determine how many packets will transmit out of one queue before switching
to the other queue, use the set qos wrr command.
set qos wrr port_type queue1_val queue2_val...
Syntax Description
Defaults The default WRR with QoS enabled for port type 1p3q1t is as follows:
•Queue 1 = 100
•Queue 2 = 150
•Queue 3 = 200
With QoS disabled, the default is 255 for all three queues.
The default WRR for port types 2q2t and 1p2q2t is 4:255.
Command Types Switch command.
Command Modes Privileged.
Usage Guidelines T he WRR weights are used to partition the bandwid th between the queue s in the e vent all queue s are not
empty. For example, weights of 1:3 mean that one queue gets 25 percent of the bandwidth and the other
gets 75 percent as long as both queues have data.
Weights of 1:3 do not necessarily lead to the same results as when the weights are 10:30. In the latter
case, more data is serviced from each queue and the la ten cy of pa ckets servi ce d f rom th e othe r que ue
goes up. For best results, set the weights so that at least one packet (maximum size) can be serviced from
the lower priority queue at a time. For the higher priority queue, set th e weights so that multiple packets
are serviced at any one time.
The values set in hardware will be close approximations of the values provided. For example, even if
you specify 0 percent, the actual value programmed will not necessarily be 0. Whatever weights you
choose, make sure that the resulting byte values programmed (see the show qos info command with the
runtime keyword) are at least equal to the MTU size.
The ratio achieved is only an approximation of what you specify since the cutoff is on a packet and
midway through a packet. For example, if you specify that the ratio services 1000 bytes out of the
low-priority queue, and there is a 1500-byte packet in the low-priority queue, the entire 1500-byte packe t
is transmitted because the hardware services an entire packet.
For 1p2q2t and 2q2t, only two queues can be set; the third queue is strict priority.
For 1p3q1t, three queues can be set; a fourth queue is strict priority.
port_type Port type; valid values are 2q2t, 1p2q2t, 1p3q1t, and 1p2q1t.
queue#_val Number of weights for queues 1, 2, or 3; valid values are f rom 1 to 255 .