Introduction to QoS

The volume of traffic moving across modern networks is increasing rapidly, placing greater pressure on available bandwidth and network performance. Although upgrading bandwidth whenever congestion occurs would be ideal, it is not always practical, cost-effective, or immediately possible. Because of this, Quality of Service, also known as QoS, becomes an essential technology for most networks, especially those carrying voice, video, business-critical applications, and high-volume data traffic. This course introduces learners to the fundamentals of QoS and explains why it is needed in today’s network environments. You will begin with the core terminology and concepts used in QoS, including classification, marking, congestion management, and congestion avoidance. These concepts help learners understand how traffic is identified, prioritized, handled, and protected during periods of congestion. The course covers traffic classification from multiple layers of the network. At Layer 2, you will learn about Class of Service, also known as CoS. At Layer 3, the course explains IP Precedence and Differentiated Services Code Point, commonly known as DSCP. You will also explore higher-level classification methods such as Network-Based Application Recognition, or NBAR, which helps identify traffic based on application behavior. In addition, the course explains important queuing mechanisms used to manage traffic flow, including FIFO, Weighted Fair Queuing, Class-Based Weighted Fair Queuing, and Low Latency Queuing. These topics help learners understand how different types of traffic can be prioritized and scheduled across network links. The training also covers congestion avoidance and traffic control mechanisms such as WRED, WTD, policing, and shaping. By the end of the course, learners will have a solid understanding of QoS concepts, tools, and techniques used to improve performance, reduce packet loss, and support reliable delivery of critical network traffic.