Cisco 12000/10700 V3.1.1 - Manual (Page 312)

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Cisco 12000/10700 v3.1.1 Router Manager User Guide
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Chapter 11 Layer 3 QoS
CoS Queue Group Configuration
IP Precedence
The IP Precedence area contains a table with two headings: IP Precedence and Drop Label.
IP Precedence—This column allows the user to map packets that have a particular IP precedence to a
WRED profile in this CoS queue group. You can map several or all precedences to the same WRED
profile if you wish. By default, precedence values are mapped so that they are not dropped due to WRED.
Drop Label—Choose a number, 0 to 6 or no-drop, which is the number of the corresponding drop label
in the WRED parameters table.
All—On checking All, the configuration of the first IP precedence is applied to all the Ip precedences.
WRED Parameters
The WRED Parameters area contains a table with four headings: Drop Label, Min Threshold, Max
Threshold, and Max Prob Denominator. The last three headings describe the actual WRED curve.
Drop Label—Drop label is a placeholder number for this set of WRED parameters. This is the number
you map IP precedence values to.
Min Threshold—When the weighted queue average is below the minimum threshold, no packets are
dropped.
Max Threshold—When the weighted queue average is above the maximum queue threshold, all packets
are dropped until the average drops below the maximum threshold.
Max Prob Denominator—When the weighted queue average is between the minimum and the maximum
thresholds, the probability that the packet is going to be dropped can be calculated by a straight line from
the minimum threshold (probability of drop will be 0) to the maximum threshold (probability of drop is
equal to the max prob denominator).