Configuring Congestion Avoidance; Configuring Tail Drop On Egress Queues - Cisco Nexus 9000 Series Configuration Manual

Configuring Queuing and Scheduling
Command or Action
Step 8 no bandwidth percent percentage
Step 9
priority level level
Step 10 queue-limit queue size [dynamic dynamic threshold]

Configuring Congestion Avoidance

You can configure congestion avoidance with tail drop or WRED features. Both features can be used in egress
policy maps.
Note
WRED and tail drop cannot be configured in the same class.

Configuring Tail Drop on Egress Queues

You can configure tail drop on egress queues by setting thresholds. The device drops any packets that exceed
the thresholds. You can specify a threshold based on the queue size or buffer memory that is used by the
queue.
Purpose
however, the strict-priority queues receive their share of
the bandwidth first. The remaining bandwidth is shared in
a weighted manner among the class configured with a
bandwidth percent. For example, if strict-priority queues
take 90 percent of the bandwidth, and you configure 75
percent for a class, the class will receive 75 percent of the
remaining 10 percent of the bandwidth.
Note
(Optional) Removes the bandwidth specification from this
class.
(Optional) Specifies the strict priority levels for the Cisco
Nexus 9000 Series switches. These levels can be from 1
to 7.
(Optional) Specifies either the static or dynamic shared
limit available to the queue for Cisco Nexus 9000 Series
switches. The static queue limit defines the fixed size to
which the queue can grow.
The dynamic queue limit allows the queue's threshold size
to be decided depending on the number of free cells
available, in terms of the alpha value.
Note
Cisco Nexus 9000 Series NX-OS Quality of Service Configuration Guide, Release 7.x
Configuring Congestion Avoidance
Before you can successfully allocate bandwidth
to the class, you must first reduce the default
bandwidth configuration on class-default and
class-fcoe.
Cisco Nexus 9200 Series switches only support
a class level dynamic threshold configuration
with respect to the alpha value. This means that
all ports in a class share the same alpha value.
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