In the past, WLANs were mainly used to transport low-bandwidth, data-application traffic. Currently, with the expansion of WLANs into vertical (such as retail, finance, and education) and enterprise environments, WLANs are used to transport high-bandwidth data applications, in conjunction with time-sensitive, multimedia applications. This requirement led to the necessity for wireless quality of service (QoS). To speed up the rate of QoS adoption and to support multi-vendor time-sensitive applications, a unified approach to wireless QoS is necessary.

When it comes to networking in modern Software Defined Networks (SDN), quality of service (QoS) is a critical factor to ensure that important applications and services perform reliably. Cisco offers QoS capabilities in their Cisco Software-Defined Access (SD-Access), Software-Defined Data Center, and Cisco Software-Defined WAN (SD-WAN) solutions.

IP was designed to provide best-effort service for delivery of data packets and to run across virtually any network transmission media and system platform. To manage applications such as VoIP, video, e-commerce, and databases, among others, a network requires quality of service (QoS). Different applications have varying requirements for delay, jitter, bandwidth, packet loss, and availability. These parameters form the basis of QoS. To successfully deploy a QoS policy, you must understand the needs of the business applications that are important to the success of the business and create an executive-backed QoS policy that prioritizes these business-critical applications according to best practices. To facilitate true end-to-end QoS on an IP network, a QoS policy must be deployed in both the campus network and the WAN. Each network segment has specific QoS policy requirements and associated best practices. When the enterprise uses a service provider network that provides Layer 3 transport, end-to-end QoS requires close coordination between the QoS policy of the enterprise and that of the service provider.