Chapter 8: Quality of Service Configuration
Quality of Service (QoS) is a general term referring to various methods of traffic management you can employ on your network to ensure that traffic you identify as
In QOS, packets are classified by the priority assigned to them. Packets can be assigned a priority in various ways. A packet can be assigned a priority based on the input port, 802.1P header or ACL. There are 8 priorities 0~7. Each packet is queued on one of the 4 internal queues based on its priority and queuing configuration. Queue 4 has the highest priority and queue 1 the lowest.
The IC39240/480 supports the following QoS methods:
•Weighted Round Robin
•802.1P Priority Queuing
•IP precedence, DSCP and DSCP Remark
•Ingress
8.1 Scheduling algorithm
There are 2 methods to schedule a packet to be transmitted from the switch : strict priority, and weighed round robin.
In strict priority, the packet with the highest priority will be sent first, the lower priority packets will be sent only when all higher priority packets have been sent. Therefore a low priority packet will not be sent if higher priority packets are present all the time.
In weighed round robin, the higher priority will not be able to hog all the XMT resources. The resources are allocated based on the weight value associated with each queue. The service of a queue will stop when the resource is used up. Then the service will go to the next queue. This will proceed with the 4 queues in a round robin fashion.
8.1.1 Configuring Weighted Round Robin
When Weighted Round Robin is enabled, the default settings are as follows:
Queue Weight
11
22
34
48
One can change the weights assigned to each queue to alter the service priorities. Based on the default values, queue 4 will be allocated more resource, hence higher priority.
To set weighted round robin settings, use the following command in EXEC mode:
57 | Asante IntraCore IC3624/48 | User’s Manual |
