RFC 3260 (rfc3260) - Page 2 of 10

New Terminology and Clarifications for Diffserv

RFC 3260    New Terminology and Clarifications for Diffserv   April 2002


   specifying classifier rules and any corresponding traffic profiles
   and metering, marking, discarding and/or shaping rules which are to
   apply...."

   As work progressed in Diffserv (as well as in the Policy WG [6]), it
   came to be believed that the notion of an "agreement" implied
   considerations that were of a pricing, contractual or other business
   nature, as well as those that were strictly technical.  There also
   could be other technical considerations in such an agreement (e.g.,
   service availability) which are not addressed by Diffserv.  It was
   therefore agreed that the notions of SLAs and TCAs would be taken to
   represent the broader context, and that new terminology would be used
   to describe those elements of service and traffic conditioning that
   are addressed by Diffserv.

      -  A Service Level Specification (SLS) is a set of parameters and
         their values which together define the service offered to a
         traffic stream by a DS domain.

      -  A Traffic Conditioning Specification (TCS) is a set of
         parameters and their values which together specify a set of
         classifier rules and a traffic profile.  A TCS is an integral
         element of an SLS.

   Note that the definition of "Traffic stream" is unchanged from RFC
   2475.  A traffic stream can be an individual microflow or a group of
   microflows (i.e., in a source or destination DS domain) or it can be
   a BA.  Thus, an SLS may apply in the source or destination DS domain
   to a single microflow or group of microflows, as well as to a BA in
   any DS domain.

   Also note that the definition of a "Service Provisioning Policy" is
   unchanged from RFC 2475.  RFC 2475 defines a "Service Provisioning
   Policy as "a policy which defines how traffic conditioners are
   configured on DS boundary nodes and how traffic streams are mapped to
   DS behavior aggregates to achieve a range of services."  According to
   one definition given in RFC 3198 [6], a policy is "...a set of rules
   to administer, manage, and control access to network resources".
   Therefore, the relationship between an SLS and a service provisioning
   policy is that the latter is, in part, the set of rules that express
   the parameters and range of values that may be in the former.

   Further note that this definition is more restrictive than that in
   RFC 3198.







Grossman                     Informational