QoS queue configuration

QoS queue configuration reduces the number of outbound queues that all switch ports use to buffer packets for 802.1p user priorities. By default the switches covered in this guide use eight queues. Change the default QoS queue configuration to four-queue mode or two-queue mode to increase the available bandwidth per queue.

Use the following commands to change the number of queues per port and display the current priority queue configuration on the switch.

Syntax:

qos queue-config < 2-queues | 4-queues | 8-queues> [strict-priority] [simple-RED]

Configures the number of outbound priority queues for all ports on the switch using one of the following options: 2-queues, 4-queues, or 8-queues.

(Default: 8-queues)


[CAUTION: ]

CAUTION: This command will execute a write memory followed by an immediate reboot, replacing the Startup configuration with the content of the current Running configuration.


The new configuration will:

  • Remove any previously configured bandwidth-min output settings

  • Set the new number of outbound port queues

If you select anything but ‘yes’ for this operation, the operation is aborted and a message stating Operation aborted appears.

strict-priority: Setting this attribute changes the queue scheduling algorithm to 'strict priority' - queued packets will be sent in strict priority order, from highest numbered queue to lowest. This parameter is optional and follows the number of queues parameter. Without that parameter the switch will operate in standard weighted-round-robin with fixed weights per queue (default). The highest priority queue is always serviced until empty.

simple-RED: This attribute optimizes the TCP/IP traffic flows under congestion by probabilistically selecting packets to drop before the switch queues become full. This parameter is optional and follows either the number of queues parameter, or the strict-priority parameter, if configured.

Syntax:

show qos queue config

Displays the current qos queue configuration.

Mapping of outbound port queues

This table shows the mapping of 802.1p priorities to outbound port queues:

Mapping 802.1p priorities to outbound port queues

802.1p priority 8 Queues (default) 4 Queues 2 Queues
1 (lowest) 1 1 1
2 2
0 (normal) 3 2
3 4
4 5 3 2
5 6
6 7 4
7 (highest) 8

Impact of QoS queue configuration on guaranteed minimum bandwidth (GMB)

Changing the number of queues removes any bandwidth-min output settings in the startup configuration, and automatically re-allocates the GMB per queue as shown in the following table.

Default GMB percentage allocations per QoS queue configuration

802.1p priority 8 Queues (default) 4 Queues 2 Queues
Queue GMB Queue GMB Queue GMB
1 (lowest) 1 2% 1 8% 1 20%
2 2 3%
0 (normal) 3 30% 2 17%
3 4 10%  
4 5 10% 3 30% 2 80%
5 6 10%  
6 7 15% 4 45%
7 (highest) 8 20%  

[NOTE: ]

NOTE: See the Management and Configuration Guide. for your switch.


Configuring the number of priority queues

To change the number of outbound priority queues for all ports on the switch, use the qos queue-config command.


[CAUTION: ]

CAUTION: The qos queue-config command executes a write memory followed by an immediate reboot, replacing the Startup configuration with the contents of the current Running configuration. In addition to setting the number of outbound port queues, the new configuration will remove any previously configured bandwidth-min output settings.


Example:

To change the number of outbound priority queues for all ports on the switch from eight queues (the default) to four:

  1. Configure the number of outbound priority queues by using the qos queue-config command.

    HP Switch(config)#: qos queue-config 4-queues
    

    A caution message is displayed (see the Caution note above) concluding with the following prompt:

    Do you wish to proceed? [Proceed/Cancel]
    
  2. Type Proceed to continue.

    A second confirmation prompt appears:

    Please confirm reset. [Yes/Cancel]
    
  3. Type Yes to initiate a write memory followed by an immediate reboot. (If you enter Cancel at either of the two prompts, the command is aborted and the current queue configuration is maintained on the switch).

    The changes will be committed to the startup configuration and the switch will reboot automatically with the new priority queue changes in effect. See Default GMB percentage allocations per QoS queue configuration for a listing of the default GMB percentages that are allocated per queue.

Viewing the QoS queue configuration

Syntax:

show qos queue-config

Displays the current priority queue configuration and memory allocations per queue.

Viewing QoS queue configuration

HP Switch(config)# show qos queue-config
Outbound Port Queue Configuration
4-queues, weighted-round-robin, simple-RED disabled.
 
         802.1p
 Queue Priority
 ----- --------
 1     1,2
 2     0,3
 3     4,5
 4     6,7