DSCPTOS

DSCPToS is a small software utility designed to convert Differentiated Services Code Point (DSCP) values to the Type of Service (ToS) byte used in IPv4 headers, and to perform the reverse conversion. It serves as a calculation aid for understanding how DSCP markings map to the ToS field, which is useful in Quality of Service (QoS) planning and testing.

Technical overview

In IPv4, DSCP is a 6-bit field that indicates per-hop behavior for packet handling, while the ToS byte comprises 8 bits, with the top 6 bits carrying the DSCP value and the bottom 2 bits reserved for ECN (Explicit Congestion Notification). DSCPToS typically implements the straightforward mapping where the ToS value is formed by shifting the DSCP value left by two bits and optionally combining it with ECN bits. The tool may accept input in decimal or hexadecimal and can present the resulting ToS byte in multiple formats. It can also perform the inverse operation, extracting DSCP and ECN from a given ToS byte.

Usage and scope

DSCPToS is used in QoS testing, device configuration validation, and educational contexts to illustrate how DSCP markings relate to the IPv4 ToS field. It is not a packet-stamping or network fabric implementation; rather, it provides a quick, deterministic way to calculate ToS values from DSCP values and vice versa, aiding engineers and students in planning and troubleshooting QoS configurations.

Availability

Tools of this type are commonly distributed as command-line utilities, sometimes as part of broader QoS or networking toolkits. Platform support varies by distribution, but portable implementations are often available for common operating systems.

See also

Differentiated Services, Type of Service, DSCP, ECN, QoS.