Configuring QoS
Congestion Avoidance
OmniSwitch AOS Release 7 Network Configuration Guide
June 2013
page 25-21
When enabled, WRP 1 applies the following color threshold values only to TCP traffic:
The minimum and maximum threshold values are a percentage of the maximum average queue length.
The OmniSwitch 6900 average queue length is calculated as follows:
1
Total Number of Cells : 46080
2
Total Number of Ports : 64
3
Number of Queuss : 8
4
Total Number of Queues: 64 * 8 = 512
5
Maximum Queue length calculated at full load : 46080 /512 = 90
When congestion of green, yellow and red traffic occurs without WRED, green has the highest prece-
dence and red and yellow are dropped. When congestion of yellow and red traffic occurs without WRED,
yellow and red have the same precedence.
The following is a many-to-one example, where one egress port is congested with multiple color TCP traf-
fic of the same priority.
Color
Min
Threshold
Max
Threshold
Drop
Probability
Gain
Red
10%
50%
36%
9
Yellow
50%
90%
30%
9
Green
90%
100%
24%
9
WRED Enabled
WRED Disabled
Input
Output
100% Green
100% Yellow
100% Green
100% Green
100% Red
100% Yellow
90-95% Yellow
50% Yellow
100% Red
0-5% Red
50% Red
80% Yellow
70-75% Yellow
55% Yellow
60% Red
25-30% Red
45% Red
90% Yellow
80-85% Yellow
60% Yellow
70% Red
15-20% Red
40% Red