Alcatel-Lucent 7950 Quality Of Service Manual page 291

the queue.
The size of the buffer pool is dictated by the queue's mbs parameter. The size of the reserved CBS portion of
the buffer pool is dictated by the queue's cbs parameter. The provisioning characteristics of the mbs and cbs
commands have not been changed.
In the case where the QoS policy is applied to a SAP on an IOM3-XP which has WRED queue support
shutdown (config>card>>fp>egress>wred-queue-control>shutdown) the queue will continue to map to
either to its default pool or the pool defined in the pool command. If the no shutdown command is executed
on the IOM, the queue will at that point be automatically moved to its own WRED pool.
Each pool created for a queue using the wred-queue command shares buffers with all other wred-queue
enabled queues on the same IOM3-XP. The WRED pool buffer management behavior is defined within the
config>card>fp>egress>wred-queue-control CLI context.
The WRED slopes within the pool are defined by the slope policy associated with the queue. When a policy
is not explicitly defined, the default slope policy is used. The slope policy enables, disables and defines the
relative geometry of the high and low WRED slopes in the pool. The policy also specifies the time average
factor used by the pool when calculating the weighted average pool depth.
As packets attempt to enter the egress queue, they are associated with either the high or low WRED slope
based on the packets profile. If the packet is in-profile, the high slope is used. The low slope is used by out-
of-profile packets. Each WRED slope performs a probability discard based on the current weighted average
pool depth.
When wred-queue is enabled for a SAP egress queue on an IOM3-XP, the queue pool and hi-priority-only
commands are ignored.
The number of wred-queue enabled queues allowed per IOM3-XP is hard coded to 7500.
The no form of the command restores the generic buffer pool behavior to the queue. The WRED pool is
removed from the system. The queue will be moved to either the default buffer pool or to a named pool if
defined and the pool exists.
Default no wred-queue
Parameters policy slope-policy-name — Specifies an existing slope policy that is used to override the default WRED
slope policy.
7950 XRS Quality of Service Guide Page 291