Queue Parameters
32 Quality of Service Guide
The buffer allocation determines how much of the Egress normal megapool is allocated for
the Egress WRED megapool, with the resv-cbs defining the amount of reserved buffers in
the Egress WRED megapool. In both cases the min and max values must be equal. The slope-
policy defines the WRED slope parameters and the time average factor used on the megapool
itself to handle congestion as the megapool buffers are used. The no shutdown command
enables the megapool. The megapools on card 1 FP 1 can be shown as follows:
*A:PE# show megapools 1 fp 1
===============================================================================
MegaPool Summary
===============================================================================
Type Id App. Pool Name Actual ResvCBS PoolSize
Admin ResvCBS
-------------------------------------------------------------------------------
fp 1/1 Egress normal n/a 282624
n/a
fp 1/1 Ingress normal n/a 374784
n/a
fp 1/1 Egress wred 24576 93696
25%
===============================================================================
*A:PE#
To configure a pool per queue, the wred-queue command is used under queue in a SAP
egress QoS policy or egress queue group template with the mode set to pool-per-queue as
follows:
qos
queue-group-templates
egress
queue-group <queue-group-name> create
queue <queue-id> create
wred-queue [policy <slope-policy-name>] mode pool-
per-queue
slope-usage default
exit
exit
exit
exit
sap-egress <policy-id> create
queue <queue-id> [<queue-type>] [create]
wred-queue [policy <policy-name>] mode pool-per-queue
slope-usage default
exit
exit
Congestion control is provided by the slope policy applied to the queue, with the slopes to be
used having been no shutdown (otherwise traffic will use the MBS drop tail or a megapool
slope). The slope-usage defines the mapping of the traffic profile to the WRED slope and
only default is allowed with pool-per-queue which gives the following mapping:
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