What is Class of Service (CoS)?

Class of Service (CoS) is a networking feature that prioritizes data traffic to improve performance and reduce latency. CoS is defined by the IEEE 802.1p standard, which assigns priority levels to network packets and is commonly used in industrial automation, VoIP, and video streaming, where certain data needs higher priority. CoS helps ensure critical traffic, like SCADA commands, is delivered without delays. CoS is implemented at Layer 2 using VLAN tagging to classify and prioritize network traffic.

Example Scenario: Real-Time SCADA Communication with CoS:

In a SCADA system, an HMI sends real-time control commands to a PLC over a managed switch. Without CoS, critical control packets may compete with regular network traffic, causing delays. CoS assigns higher priority to control data, ensuring immediate delivery even during network congestion preventing communication delays between the HMI and PLC, maintaining real-time system responsiveness. As a result, industrial processes run smoothly without interruptions or unsafe conditions.

Content created by Mike Day