RFC 2430 (rfc2430) - Page 3 of 16

A Provider Architecture for Differentiated Services and Traffic Engineering (PASTE)

RFC 2430                         PASTE                      October 1998


3.0 Introduction

   The next generation of the Internet presents special challenges that
   must be addressed by a single, coordinated architecture.  While this
   architecture allows for distinction between ISPs, it also defines a
   framework within which ISPs may provide end-to-end differentiated
   services in a coordinated and reliable fashion.  With such an
   architecture, an ISP would be able to craft common agreements for the
   handling of differentiated services in a consistent fashion,
   facilitating end-to-end differentiated services via a composition of
   these agreements.  Thus, the goal of this document is to describe an
   architecture for providing differentiated services within the ISPs of
   the Internet, while including support for other forthcoming needs
   such as traffic engineering.  While this document addresses the needs
   of the ISPs, its applicability is not limited to the ISPs.  The same
   architecture could be used in any large, multiprovider catenet
   needing differentiated services.

   This document only discusses unicast services.  Extensions to the
   architecture to support multicast are a subject for future research.

   One of the primary considerations in any ISP architecture is
   scalability.  Solutions that have state growth proportional to the
   size of the Internet result in growth rates exceeding Moore's law,
   making such solutions intractable in the long term.  Thus, solutions
   that use mechanisms with very limited growth rates are strongly
   preferred.

   Discussions of differentiated services to date have frequently
   resulted in solutions that require per-flow state or per-flow
   queuing.  As the number of flows in an ISP within the "default-free
   zone of the Internet" scales with the size of the Internet, the
   growth rate is difficult to support and argues strongly for a
   solution with lower state requirements.  Simultaneously, supporting
   differentiated services is a significant benefit to most ISPs.  Such
   support would allow providers to offer special services such as
   priority for bandwidth for mission critical services for users
   willing to pay a service premium.  Customers would contract with ISPs
   for these services under Service Level Agreements (SLAs).  Such an
   agreement may specify the traffic volume, how the traffic is handled,
   either in an absolute or relative manner, and the compensation that
   the ISP receives.

   Differentiated services are likely to be deployed across a single ISP
   to support applications such as a single enterprise's Virtual Private
   Network (VPN).  However, this is only the first wave of service
   implementation.  Closely following this will be the need for
   differentiated services to support extranets, enterprise VPNs that



Li & Rekhter                 Informational