You can find information on differentiated services and quality of service from print and online sources.
For more information on quality-of-service theory and practice, refer to the following books:
Ferguson, Paul and Geoff Huston. Quality of Service. John Wiley & Sons, Inc., 1998.
Kilkki, Kalevi. Differentiated Services for the Internet. Macmillan Technical Publishing, 1999.
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.
The Differentiated Services Working Group of the IETF maintains a web site with links to Diffserv Internet drafts at http://www.ietf.org/html.charters/diffserv-charter.html.
Router manufacturers such as Cisco Systems and Juniper Networks provide information on their corporate web sites that describes how Differentiated Services are implemented in their products.
ipqosconf(1M) - Describes the command for setting up the IPQoS configuration file
ipqos(7ipp) – Describes the IPQoS implementation of the Diffserv architectural model
ipgpc(7ipp) – Describes the IPQoS implementation of a Diffserv classifier
tokenmt(7ipp) – Describes the IPQoS tokenmt meter
tswtclmt(7ipp) – Describes the IPQoS tswtclmt meter
dscpmk(7ipp) – Describes the DSCP marker module
dlcosmk(7ipp) – Describes the IPQoS 802.1D user-priority marker module
flowacct(7ipp)– Describes the IPQoS flow-accounting module
acctadm(1M) – Describes the command that configures the Oracle Solaris extended accounting facilities. The acctadm command includes IPQoS extensions.