RFC 2474: Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers
RFC 1455: Physical Link Security Type of Service
RFC 1349: Type of Service in the Internet Protocol Suite
Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers
RFC 3168: The Addition of Explicit Congestion Notification (ECN) to IP
RFC 3260: New Terminology and Clarifications for Diffserv
RFC 8436: Update to IANA Registration Procedures for Pool 3 Values in the Differentiated Services Field Codepoints (DSCP) Registry