Using Quality of Service in Your Network

Quality of Service (QoS) is:

• A mechanism for the management of bandwidth
• The ability to give preferential treatment to some packets over others
• Based upon packet classification and forwarding treatment

You configure packet preference and forwarding treatment based upon a flow‘s sensitivity to delay, delay variation (jitter), bandwidth, availability and packet drop. QoS uses packet priority, in conjunction with queue treatment configuration, to determine the interface‘s inbound and forwarding behavior for this packet. Packet preference and forwarding treatment for a given flow can be applied to roles configured in Extreme Networks policy.

Without QoS, all packets are treated as though the delivery requirements and characteristics of any given packet are equal to any other packet. In other words, non-QoS packet delivery is not able to take into account application sensitivity to packet delay, jitter, amount of bandwidth required, packet loss, or availability requirements of the flow. QoS provides management mechanisms for these flow characteristics.

QoS achieves its bandwidth management capabilities by:

• Setting priorities that define traffic handling
• Dedicating bandwidth and prioritizing queuing for specific applications, and reducing packet transmission delay and jitter
• Managing congestion by shifting packet loss to applications that can tolerate it

The Flex-Edge feature, supported on the S- and K-Series switches, provides the unique capability to classify traffic as it enters the switch. Traffic critical to ensuring the operational state of the network and to maintain application continuity is identified and prioritized at ingress, prior to being passed on for packet processing. See Flex-Edge (S-, K-Series) for more details.