The Evolution of the Generalized Differentiated Services Architecture and the Changing Role of the Internet Engineering Task Force

Abstract

Due to the transition from narrowband access to broadband access, heterogeneous requirements for traffic qualities become increasingly important taking into account the necessities for prioritization of data packets and quality of service guarantees. A transition to active network management and subsequently to a more intelligent Internet traffic architecture is required. In meantime, the role of the IETF changed from developing and enforcing a universal connectivity TCP traffic infrastructure to a platform for dealing with the increasing need for variety in the design of different traffic management infrastructures and the continuous search for new technological solutions.Quality of service differentiation standard tracks was already initiated under the heading of Integrated Services/Resource Reservation Protocol (IntServ/RSVP) and Differentiated Services (DiffServ) architectures nearly fifteen years ago. The analysis of this standard setting process during the last fifteen years shows that neither DiffServ architecture nor IntServ/RSVP has reached the final status of Internet standard. Moreover, important developments of network management design for DiffServ networks did not even reach standard track status, but are considered to be on the non-standard track. This includes the Configuration Guidelines for DiffServ Service Classes. Moreover, Procedures for Modifying the RSVP reached the status of Best Current Practice for the Internet community.From the perspective of fostering the evolutionary search for innovative traffic management architectures the increasing role of optional (non-obligatory) non-standard tracks for quality of service differentiated network management should not be considered as a weakness but as a strength of the IETF. As a standard setting agency the IETF cannot take over entrepreneurial decisions regarding the choice of traffic management investment and the required allocation mechanisms for fulfilling the heterogeneous requirements for traffic qualities and implementing incentive compatible pricing mechanisms. In contrast to the technical neutrality of TCP, market driven network neutrality requires an entrepreneurial search for quality of service differentiation avoiding incentives for Internet traffic service providers to discriminate between possible network applications on the basis of network capacity requirements.Therefore, the traditional market split of telecommunications providers into specialized services based on active traffic management for the provision of high quality of service levels (e.g. VoIP, IPTV) and passive (TCP-based) Internet is unlikely to remain stable within the IP-based next generation networks. A forward looking economic model of active traffic management is provided within a generalized DiffServ architecture based on congestion pricing and quality of service differentiation. Within this “umbrella” architecture for traffic management, a flexible framework for different traffic quality differentiation strategies is provided. Since its basic characteristic is that all applications are bearing the opportunity costs of the required traffic capacities the traditional differentiation between managed services and other IP-based Internet services becomes obsolete. In order to guarantee the high quality of VoIP or IPTV, top quality classes can be introduced using the principle of resource reservation with guaranteed end-to-end control. For applications which are less delay sensitive but still require some active traffic management lower traffic quality classes are sufficient, for those applications which are not delay sensitive a “best effort” transmission class may be introduced.In order to provide incentive compatible quality of service differentiation within a generalized DiffServ architecture transmission charges must be monotone increasing with the highest quality class paying the highest transmission charges, and the best effort class may be provided for free.