Active Queue Management (Aqm) Via Dynamic Buffer Limiting (Dbl) - Cisco Catalyst 4500 Series Software Configuration Manual

Configuring VSS QoS
Switch(config-pmap-c)# queue-limit 4048
Switch(config-pmap-c)# exit
Switch(config-pmap)# exit
Switch(config)# interface gigabitethernet1/1
Switch(config-if)# service-policy output policy1
Switch(config-if)# end
Switch#
Switch# show policy-map policy1
Policy Map policy1
Switch#

Active Queue Management (AQM) via Dynamic Buffer Limiting (DBL)

AQM provides buffering control of traffic flows prior to queuing a packet into a transmit queue of a port.
This is of significant interest in a shared memory switch, ensuring that certain flows do not hog the
switch packet memory.
The supervisor engine supports active switch buffer management via DBL.
Note
Except for the default class of traffic (class class-default), you can configure DBL action only when at
least one of the other queuing action is configured.
To configure class-level dbl action along with shaping in a service policy, perform this task:
Command
Step 1
Switch# configure terminal
Step 2
Switch(config)# policy-map
policy-map-name
Step 3
Switch(config-pmap)# class class-name
Step 4
Switch(config-pmap-class)# shape
average cir-bps
Step 5
Switch(config-pmap-class)# dbl
Step 6
Switch(config-pmap-class)# exit
Step 7
Switch(config-pmap)# exit
Step 8
Switch(config)# interface interface-id
Step 9
Switch(config-interface)#
service-policy output policy-map-name
Step 10
Switch(config-interface)# end
Catalyst 4500 Series Switch, Cisco IOS Software Configuration Guide - Cisco IOS XE 3.9.xE and IOS 15.2(5)Ex
44-34
Class class1
shape average 256000
queue-limit 4048
Purpose
Enters global configuration mode.
Creates a policy map by entering the policy-map name, and enter
policy-map configuration mode.
By default, no policy maps are defined.
Specifies the name of the class whose traffic policy you want to
create or change, and enter policy-map class configuration mode.
By default, no traffic classes are defined.
Enables average-rate traffic shaping.
Specify the committed information rate, the bit rate that traffic is
shaped to, in bps. The range is 32000 to 10000000000 bps.
By default, average-rate traffic shaping is disabled.
Enables DBL on the queue associated with this class of traffic
Returns to policy-map configuration mode.
Returns to global configuration mode.
Specifies a physical port and enter interface configuration mode.
Specifies the policy-map name, and apply it a physical interface.
Returns to privileged EXEC mode.
Chapter 44 Configuring Quality of Service