At which OSI model layer does DiffServ operate?

DiffServ, or Differentiated Services, operates at Layer 3 of the OSI model, which is the Network layer. At this layer, packets are routed between different networks, and DiffServ provides a mechanism for classifying and managing network traffic. This classification allows for differentiated services based on the quality of service (QoS) required by various types of data flows.

In practice, DiffServ defines a set of code points in the IP header called DSCP (Differentiated Services Code Point) that indicate how packets should be treated by routers in the network. By marking packets with different levels of priority, routers can make more informed decisions on how to forward traffic, ensuring that more critical or time-sensitive data, such as voice or video, receives preferential treatment over less urgent data.

The other layers, such as Layer 1 (Physical), Layer 2 (Data Link), and Layer 4 (Transport), do not encompass the traffic management features provided by DiffServ. Layer 1 deals with the physical transmission of data over a medium, Layer 2 involves node-to-node data transfer and error detection, and Layer 4 manages end-to-end communication and session management but does not include the type of traffic classification that DiffServ facilitates at