Definition of the Differentiated Services Field (DS Field) in the IPv4 and IPv6 Headers

Differentiated services enhancements to the Internet protocol are intended to enable scalable service discrimination in the Internet without the need for per-flow state and signaling at every hop.A variety of services may be built from a small, well-defined set of building blocks which are deployed in network nodes.The services may be either end-to-end or intra-domain; they include both those that can satisfy quantitative performance requirements (e.g., peak bandwidth) and those based on relative performance (e.g., "class" differentiation).Services can be constructed by a combination of:-setting bits in an IP header field at network boundaries (autonomous system boundaries, internal administrative boundaries, or hosts), -using those bits to determine how packets are forwarded by the nodes inside the network, and -conditioning the marked packets at network boundaries in accordance with the requirements or rules of each service.Nichols, et.al.