Network Element Service Specification Template
RFC 2216

Type RFC - Informational (September 1997; No errata)
Last updated 2013-03-02
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Network Working Group                                         S. Shenker
Request for Comments: 2216                                 J. Wroclawski
Category: Informational                               Xerox PARC/MIT LCS
                                                          September 1997

             Network Element Service Specification Template

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.


   This document defines a framework for specifying services provided by
   network elements, and available to applications, in an internetwork
   which offers multiple qualities of service. The document first
   provides some necessary context -- including relevant definitions and
   suggested data formats -- and then specifies a "template" which
   service specification documents should follow. The specification
   template includes per-element requirements such as the service's
   packet handling behavior, parameters required and made available by
   the service, traffic specification and policing requirements, and
   traffic ordering relationships.  It also includes evaluation criteria
   for elements providing the service, and examples of how the service
   might be implemented (by network elements) and used (by


   This document defines the framework used to specify the functionality
   of internetwork system components which support the the ability to
   provide multiple, dynamically selectable qualities of service to
   applications using an internetwork. The behavior of individual
   routers and subnetworks is captured as a set of "services", some or
   all of which may be offered by each element. The concatenation of
   these services along the end-to-end data paths used by an application
   provides overall quality of service control.

   The definition of a service states what is required of a router (or,
   more generally, any network element; a router, switch, subnet, etc.)
   which supports a particular service. The service definition also

Shenker & Wroclawski         Informational                      [Page 1]
RFC 2216            Network Element Service Template      September 1997

   specifies parameters used to invoke the service, the relationship
   between those parameters and the service delivered, and the end-to-
   end behavior obtained by concatenating several instances of the

   Each service definition also specifies the interface between that
   service and the environment. This includes the parameters needed to
   invoke the service, informational parameters which the service must
   make available for use by setup, routing, and management mechanisms,
   and information which should be carried between end-nodes and network
   elements by those mechanisms in order to achieve the desired end-to-
   end behavior. However, a service definition does not describe the
   specific protocols or mechanisms used to establish state in the
   network elements for flows that use the described service.

   Services defined following the guidelines of this document are
   intended for use both within the global Internet and private IP
   networks. In certain cases a concatenation of network element
   services may be used to provide a range of end-to-end behaviors, some
   more suited to a decentralized internet and some more appropriate for
   a tightly managed private network. This document points out places
   where such distinction may be appropriate.

   This document is comprised of three parts.  The first defines some
   terms used both in this document and in the various service
   specification documents.  The second discusses data formats and
   representations.  The third portion of the document describes the
   various components of the service specification template.


   The following terms are used throughout this document. Service
   specification documents should employ the same terms to express these

 o Quality of Service (QoS)

   In the context of this document, quality of service refers to the
   nature of the packet delivery service provided, as described by
   parameters such as achieved bandwidth, packet delay, and packet loss
   rates. Traditionally, the Internet has offered a single quality of
   service, best-effort delivery, with available bandwidth and delay
   characteristics dependent on instantaneous load. Control over the
   quality of service seen by applications is exercised by adequate
   provisioning of the network infrastructure. In contrast, a network
   with dynamically controllable quality of service allows individual
   application sessions to request network packet delivery
   characteristics according to their perceived needs, and may provide
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