RFC 3290 (rfc3290) - Page 3 of 56
An Informal Management Model for Diffserv Routers
Alternative Format: Original Text Document
RFC 3290 Diffserv Informal Management Model May 2002 1. Introduction Differentiated Services (Diffserv) [DSARCH] is a set of technologies which allow network service providers to offer services with different kinds of network quality-of-service (QoS) objectives to different customers and their traffic streams. This document uses terminology defined in [DSARCH] and [NEWTERMS] (some of these definitions are included here in Section 2 for completeness). The premise of Diffserv networks is that routers within the core of the network handle packets in different traffic streams by forwarding them using different per-hop behaviors (PHBs). The PHB to be applied is indicated by a Diffserv codepoint (DSCP) in the IP header of each packet [DSFIELD]. The DSCP markings are applied either by a trusted upstream node, e.g., a customer, or by the edge routers on entry to the Diffserv network. The advantage of such a scheme is that many traffic streams can be aggregated to one of a small number of behavior aggregates (BA), which are each forwarded using the same PHB at the router, thereby simplifying the processing and associated storage. In addition, there is no signaling other than what is carried in the DSCP of each packet, and no other related processing that is required in the core of the Diffserv network since QoS is invoked on a packet-by-packet basis. The Diffserv architecture enables a variety of possible services which could be deployed in a network. These services are reflected to customers at the edges of the Diffserv network in the form of a Service Level Specification (SLS - see [NEWTERMS]). Whilst further discussion of such services is outside the scope of this document (see [PDBDEF]), the ability to provide these services depends on the availability of cohesive management and configuration tools that can be used to provision and monitor a set of Diffserv routers in a coordinated manner. To facilitate the development of such configuration and management tools it is helpful to define a conceptual model of a Diffserv router that abstracts away implementation details of particular Diffserv routers from the parameters of interest for configuration and management. The purpose of this document is to define such a model. The basic forwarding functionality of a Diffserv router is defined in other specifications; e.g., [DSARCH, DSFIELD, AF-PHB, EF-PHB]. This document is not intended in any way to constrain or to dictate the implementation alternatives of Diffserv routers. It is expected that router implementers will demonstrate a great deal of variability in their implementations. To the extent that implementers are able Bernet, et. al. Informational
