Juniper JUNOSE SOFTWARE FOR E SERIES 11.3.X - QUALITY OF SERVICE CONFIGURATION GUIDE 2010-09-22 Configuration Manual page 64

JunosE 11.3.x Quality of Service Configuration Guide
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Dynamic queues on edge-facing interfaces where the number of queues is relatively
large (thousands).
As shown in Figure 7 on page 35, queue lengths extend to oversubscribe memory when
aggregate memory utilization is low, and contract to strictly partition memory when
memory utilization is high. Dynamic thresholding enforces fairness when free buffers are
scarce and promotes sharing when buffers are plentiful. Dynamic queue thresholds are
discussed in "Queuing and Buffer Management Overview" on page 17. Figure 7 on page 35
illustrates WRED behavior with dynamic queue thresholding.
To configure WRED to run on queues whose limits dynamically expand and contract, use
the percent keyword when you configure thresholds in a drop profile. For example:
host1(config)#drop-profile internetDropProfile
host1(config-drop-profile)#average-length-exponent 9
host1(config-drop-profile)#committed-threshold percent 30 90 4
host1(config-drop-profile)#conformed-threshold percent 25 90 5
host1(config-drop-profile)#exceeded-threshold percent 20 90 6
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