Allied Telesis AT-9724TS Configuring the Combination Queue, Parameter Description Max. Packets

You may assign the following values to the QoS classes to set the scheduling.

Parameter	Description
Max. Packets	Specifies the maximum number of packets the above specified hardware priority queue will be allowed to
	transmit before allowing the next lowest priority queue to transmit its packets.A value between 0 and 15 can
	be specified.

Click Apply to implement changes made.

Note: Entering a 0 for the Max Packets field in the QoS Output Scheduling Configuration window above will create a Combination Queue. For more information on implementation of this feature, see the next section, Configuring the Combination Queue.

Configuring the Combination Queue

Utilizing the QoS Output Scheduling Configuration window shown above, the AT-9724TS can implement a combination queue for forwarding packets. This combination queue allows for a combination of strict and weight-fair (weighted round-robin “WRR”) scheduling for emptying given classes of service.To set the combination queue, enter a 0 for the Max Packets entry of the corresponding priority classes of service listed in the window above. Priority classes of service that have a 0 in the Max Packet field will forward packets with strict priority scheduling.The remaining classes of service, that do not have a 0 in their Max Packet field, will follow a weighted round-robin (WRR) method of forwarding packets – as long as the priority classes of service with a 0 in their Max Packet field are empty.When a packet arrives in a priority class with a 0 in its Max Packet field, this class of service will automatically begin forwarding packets until it is empty. Once a priority class of service with a 0 in its Max Packet field is empty, the remaining priority classes of service will reset the weighted round-robin (WRR) cycle of forwarding packets, starting with the highest available priority class of service. Priority classes of service with an equal level of priority and equal entries in their Max Packet field will empty their fields based on hardware priority scheduling.The Max Packet parameter allows you to specify the maximum number of packets a given priority class of service can transmit per weighted round-robin (WRR) scheduling cycle.This provides for a controllable CoS behavior while allowing other classes to empty as well.A value between 0 and 15 packets can be specified per priority class of service to create the combination queue. The example window below displays an example of the combination queue where Class-1 will have a strict priority for emptying its class, while the other classes will follow a weight fair scheduling.

Figure 6- 51. QoS Output Scheduling Configuration window – Combination queue example

Allied Telesyn AT-9724TS High-Density Layer 3 Stackable Gigabit Ethernet Switch 69