Brocade Multi-Service IronWare QoS and Traffic Management Configuration Guide (Supporting R05.6.00) - Manual (Page 140)

126 Multi-Service IronWare QoS and Traffic Management Configuration Guide
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Scheduling traffic for forwarding
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• If you enter the min-avg-queue-size equal to what is already configured as the
max-avg-queue-size, then the min-avg-queue-size will be decremented by 64 to make
it different from the max-avg-queue-size, the following warning is displayed:
“Warning - min-avg-queue-size is decreased to (min-avg-queue-size - 64) as min and
max should be different to be effective.”
• If you enter the max-avg-queue-size equal to what is already configured as the
min-avg-queue-size, then the max-avg-queue-size will be incremented by 64 to make it
different from the min-avg-queue-size, the following warning is displayed:
“Warning - max-avg-queue-size is increased to (max-avg-queue-size + 64) as the min &
max should be different to be effective.”
• If you enter the min-average-queue-size equal to the max-avg-queue-size, the
max-avg-queue-size will be incremented by 64 to make it different from
min-avg-queue-size, the following warning is displayed:
“Warning - max-avg-queue-size increased to (max-avg-queue-size + 64) as min & max
should be different to be effective.” Unless you enter the max-avg-queue-size and
min-avg-queue-size equal to 32768, the min-avg-queue-size will be decremented.
Displaying the WRED configuration
To view a WRED configuration, use the following command.
Brocade# show qos wred
QType Enable AverWt MaxQSz DropPrec MinAvgQSz MaxAvgQSz MaxDropProb MaxPktSz
0 Yes 9(0.19%) 16384 0 5696 16384 2% 16384
1 4864 16384 4% 16384
2 4096 16384 9% 16384
3 3264 16384 10% 16384
1 No
2 No
3 Yes 9(0.19%) 16384 0 6528 16384 2% 16384
1 5696 16384 4% 16384
2 4864 16384 9% 16384
3 4096 16384 9% 16384
4 No
5 No
6 No
7 No
Scheduling traffic for forwarding
If the traffic being processed by a Brocade device is within the capacity of the device, all traffic is
forwarded as received. Once we reach the point where the device is bandwidth constrained, it
becomes subject to drop priority if configured as described in
“Configuring packet drop priority
using WRED” on page 120 or traffic scheduling as described in this section.
The Brocade devices classify packets into one of eight internal priorities. Traffic scheduling allows
you to selectively forward traffic according to the forwarding queue that is mapped to according to
one of the following schemes:
• Strict priority-based scheduling – This scheme guarantees that higher-priority traffic is always
serviced before lower priority traffic. The disadvantage of strict priority-based scheduling is
that lower-priority traffic can be starved of any access.