Hsmda Slope Policy Mbs Parameter - Alcatel-Lucent 7450 Quality Of Service Manual

Ethernet service switch; service router; extensible routing system

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HSMDA QoS Model

HSMDA Slope Policy MBS Parameter

Unlike standard queues, HSMDA queues do not have a configured maximum buffer size

(MBS) parameter. Instead the high and low RED slopes are used for all queue congestion

control functions by the queue. The system uses an MBS value to define how much buffering

an HSMDA queue may use, but it is contained in the HSMDA slope policy. The slope policy

uses the configured MBS value to provide context for the slope parameters which are defined

as percentages of MBS.

HSMDA Slope Policy Slope Parameters

Each slope in the slope policy is defined by three points; the starting-depth, slope maximum-

depth and the slope maximum-discard-probability. Only three points are required since the

starting-depth value implies a starting-discard-probability of zero percent. The starting-depth

defines at which queue depth the slope starts to rise from zero. The maximum-depth point

defines the queue depth where the slope ends and goes straight to 100%. The maximum-

discard-probability defines the how high the slope rises from zero before going straight to

100% at the maximum-depth point.

If the starting-depth and maximum-depth percentages are equal, the system performs a simple

drop tail; the discard probability slope is essentially non-existent in this case.

The system takes the configured slope parameters and uses them to calculate the HSMDA

internal slope definitions:

Figure 50: High and Low RED Slopes

Queue Depth Utilization

Quality of Service Guide