Setting Up CBWFQ

Use the set port queue service cbwfq command to set a port, port range, or module to use class-based weighted fair queuing (CBWFQ) queue servicing. The syntax of the command is:

(configure)# set port queue service {{<mod-num> | <mod-swport-range>} [..., {<mod-num> | <mod-swport-range>}] | all-ports} cbwfq queue <queue> bit-rate <rate> normal-burst <normal-burst> [exceed {drop | max-burst <max-burst> [weight <weight>]}]

Table 25-24. Keywords, Arguments, and Options
Keyword, Argument or Option	Definition
<mod-num>	The slot number of a module. If you specify <mod-num>, all ports on the module are set to use CBQ.
<mod-swport-range>	The slot number of a module, and, either a port number, or a range of port numbers having the format Px-Py. For example: To specify port 1 on the module in slot 3, enter 3/1. To specify ports 1 through 5 on the module in slot 3, enter 3/1-5. If you specify <mod-swport-range>, the port or range of ports that you specify is set use CBQ.
all-ports	All ports in the chassis. If you specify all-ports, all ports on all modules in the chassis are set to use CBQ.
<queue>	The queue number, which can range from 0 to 7.
<rate>	The maximum bits per second that you want to assign to the queue. If the switch is operating in Fabric mode 1, the rate can range from 220 Kbps to 1.5 Gbps. If the switch is operating in Fabric mode 2, the rate can range from 270 Kbps to 1.5 Gbps Entering a rate of 0 disables the queue.
<normal-burst>	The maximum size of burst that is guaranteed transfer. Bursts that are smaller than this size are guaranteed transfer. Bursts that are larger than this size are either serviced by WFQ or dropped (whichever action that you specify). The default setting is servicing by WFQ and the default weight for the queues. The normal burst can range from 0 to 15,000 bytes. Avaya recommends a value of 6000. Enter this setting in a multiple of four. If you do not enter a multiple of four, the switch rounds down the number that you enter to a multiple of four. For example, if you enter a normal burst size of 43 byes, the switch converts the setting to 40 bytes. If you enter a normal burst size of 0,1,2 or 3, the switch stores a value of 0 and no data is forwarded from the queue.
exceed	The action that you want the switch to take if the bit rate exceeds the guaranteed bit rate that you specify. The switch can either drop packets or forward them based on the weight of the queue.
drop	Indicates that you want the switch to drop packets when the bit rate exceeds the guaranteed bit rate.
<max-burst>	The maximum size burst that is serviced by WFQ once the normal burst has been exceeded. Bursts that are smaller than this size are serviced by WFQ. Bursts that are larger than this size are dropped. If you set this threshold to the same value as normal burst, the maximum burst capability is disabled. The maximum burst can range from the normal burst size to 15,000.Avaya recommends a value of 6000. Increase the maximum burst setting as the burstiness of the traffic increases. NOTE: Note: The maximum burst setting must be greater than or equal to the normal burst. Enter this setting in a multiple of four. If you do not enter a multiple of four, the switch rounds down the number that you enter to a multiple of four. For example, if you enter a maximum burst size of 43 byes, the switch converts the setting to 40 bytes.If you enter a maximum burst size of 0,1,2 or 3, the switch stores a value of 0 and no data is forwarded from the queue.
<weight>	The weight that you want to assign to the queue. Weights can range from 1to 254.

NOTE: The switch does not drop packets on egress queue 7, even if you specify the drop keyword. This restriction ensures that traffic management packets are not discarded by the bandwidth-limiting functions. In spite of the ability of egress queue 7 to exceed its bandwidth limit, the queue is subject to a fairness mechanism that prevents other queues (6 through 0) from being starved. Note that, when you specify drop, the bandwidth of queue 7 is limited if lower priority queues require service and have not reached their bandwidth guarantee.