The length of a queue within an egress queue group template can be configured as a target queue delay, in ms, instead of an absolute byte/kbytes value. The queue MBS is calculated from the queue delay and the administrative PIR, with the MBS [kB] being approximately the value of ((queue delay[ms]/1000) ✕ (PIR[kb/s] / 8)).The queue delay is configured as follows:
configure
qos
queue-group-templates
egress
queue-group queue-group-name create
queue queue-id
queue-delay msThe queue-delay command and the mbs command are mutually exclusive. To change between the mbs and queue-delay parameters, the current parameter must be removed before adding the new parameter; that is, changing from mbs to queue-delay requires a no mbs before the queue-delay is configured and changing from queue-delay to mbs requires a no queue-delay before the mbs is configured. If queue-delay is configured for an egress queue group queue, it is not possible to override the MBS for that queue.
The following is an example of configuring queue delay and the resulting MBS:
*A:PE# configure qos queue-group-templates egress queue-group "qg2"
*A:PE>cfg>qos>qgrps>egr>qgrp# info
----------------------------------------------
queue 1 best-effort create
rate 50000
queue-delay 100
exit
----------------------------------------------
*A:PE>cfg>qos>qgrps>egr>qgrp# exit all
*A:PE# show pools access-egress 5/1/1 queue-group "qg2" instance 1
...
===============================================================================
Queue : accQGrp->qg2:1(5/1/1)->1
===============================================================================
FC Map : not-applicable
Dest Tap : not-applicable Dest FP : not-applicable
Admin PIR : 50000 Oper PIR : 50000
Admin CIR : 0 Oper CIR : 0
Admin MBS : 612 KB Oper MBS : 612 KB
High-Plus Drop Tail : 612 KB High Drop Tail : 612 KB
Low Drop Tail : 540 KB Exceed Drop Tail : 480 KB
CBS : 0 KB Depth : 0
Slope : not-applicable