QoS per-hop behavior fundamentals: classification, marking, queuing, congestion, and policing

By the end you’ll be able to

• Explain the purpose of QoS and identify why delay, jitter, loss, and bandwidth contention matter for different application types.
• Explain classification and marking as QoS functions, including the role of Layer 2 CoS and Layer 3 DSCP markings.
• Interpret per-hop behavior as the forwarding treatment a device applies to packets based on their classification and marking.