RFC 2474, Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers – Describes an enhancement to the type of service (ToS) field or DS fields of the IPv4 and IPv6 packet headers to support differentiated services
RFC 2475, An Architecture for Differentiated Services – Provides a detailed description of the organization and modules of the Diffserv architecture
RFC 2597, Assured Forwarding PHB Group – Describes how the assured forwarding (AF) per-hop behavior works.
RFC 2598, An Expedited Forwarding PHB – Describes how the expedited forwarding (EF) per-hop behavior works
Internet-Draft, An Informal Management Model for Diffserv Routers – Presents a model for implementing the Diffserv architecture on routers.