DSCPKlassen

DSCPKlassen refers to the set of code points used in Differentiated Services (DiffServ) to classify and manage network traffic for quality of service (QoS). The DSCP (Differentiated Services Code Point) is a 6-bit field in the IP header that selects a Per-Hop Behavior (PHB) for forwarding decisions. DSCP-based QoS enables scalable handling of packets by marking traffic at the network edge and applying designated forwarding rules across the core.

The DSCP space is organized into several families. The Class Selector (CS) set uses eight values, CS0 through CS7, where CS0 generally represents Best Effort. The Expedited Forwarding (EF) PHB is reserved for low-loss, low-latency traffic and uses a specific code point. The Assured Forwarding (AF) class defines four classes, each with three drop-precedence levels, denoted AF11, AF12, AF13, AF21, AF22, AF23, AF31, AF32, AF33, AF41, AF42, AF43, for a total of twelve AF code points.

In operation, edge devices mark outbound packets according to a network policy, and intermediate routers map DSCP marks to queueing and scheduling decisions that reflect the desired PHB. Packets may be re-marked or stripped when crossing administrative boundaries or exiting to other networks.

Standards and references: DSCP is defined in the DiffServ framework, notably in RFC 2474 and RFC 2475, with ECN defined in RFC 3168. Together, these specifications support interoperable QoS by propagating consistent PHBs across diverse networks.