Alcatel-Lucent 7450 Quality Of Service Manual page 528

Overview
The resulting operational PIRs are then set such that the scheduler or agg-rate rate is not
exceeded. To achieve the best precision, queues must be configured to use adaptation-rule
pir max cir max to prevent the actual queue rate used exceeds that determined by LUB.
Example
Taking a simple scenario with 5 egress SAP queues all without rates configured but with each
queue parented to a different level in a parent scheduler which has a rate of 100Mb/s, see
Figure
The resulting bandwidth distribution is shown in
sent with and without LUB applied, then when 20Mbps and 40Mbps are sent on queues 3 and
5, respectively, again with and without LUB applied. As can be seen, the distribution of
bandwidth in the case where traffic is sent and LUB is enabled is based upon the LUB-
weights described above.
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• Else if a queue has accumulated work then its LUB-weight is set to 50. The work is
determined by the queue having built up a depth of packets, or its offered rate is
increasing since last sample period. The aim is to assign more of the unused
bandwidth to queues needing more capacity. No attempt is made to distribute based
on a queues relative priority level or weight within the hierarchy.
• Otherwise, a queue's LUB-weight is 1
33.
Figure 33: Limit Unused Bandwidth Example
Queues
5
4
3
2
1
Level
Figure
CVLANs
(Scheduler Rate)
100M
al_0610
34. Firstly, when no traffic is being
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