A Lower Effort Per-Domain Behavior (PDB) for Differentiated Services
RFC 3662

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Network Working Group                                           R. Bless
Request for Comments: 3662                            Univ. of Karlsruhe
Category: Informational                                       K. Nichols
                                                              Consultant
                                                               K. Wehrle
                                                 Univ. of Tuebingen/ICSI
                                                           December 2003

  A Lower Effort Per-Domain Behavior (PDB) for Differentiated Services

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.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document proposes a differentiated services per-domain behavior
   (PDB) whose traffic may be "starved" (although starvation is not
   strictly required) in a properly functioning network.  This is in
   contrast to the Internet's "best-effort" or "normal Internet traffic"
   model, where prolonged starvation indicates network problems.  In
   this sense, the proposed PDB's traffic is forwarded with a "lower"
   priority than the normal "best-effort" Internet traffic, thus the PDB
   is called "Lower Effort" (LE).  Use of this PDB permits a network
   operator to strictly limit the effect of its traffic on "best-
   effort"/"normal" or all other Internet traffic.  This document gives
   some example uses, but does not propose constraining the PDB's use to
   any particular type of traffic.

1.  Description of the Lower Effort PDB

   This document proposes a differentiated services per-domain behavior
   [RFC3086] called "Lower Effort" (LE) which is intended for traffic of
   sufficiently low value (where "value" may be interpreted in any
   useful way by the network operator), in which all other traffic takes
   precedence over LE traffic in consumption of network link bandwidth.
   One possible interpretation of "low value" traffic is its low
   priority in time, which does not necessarily imply that it is
   generally of minor importance.  From this viewpoint, it can be

Bless, et al.                Informational                      [Page 1]
RFC 3662                    Lower Effort PDB               December 2003

   considered as a network equivalent to a background priority for
   processes in an operating system.  There may or may not be memory
   (buffer) resources allocated for this type of traffic.

   Some networks carry traffic for which delivery is considered
   optional; that is, packets of this type of traffic ought to consume
   network resources only when no other traffic is present.
   Alternatively, the effect of this type of traffic on all other
   network traffic is strictly limited.  This is distinct from "best-
   effort" (BE) traffic since the network makes no commitment to deliver
   LE packets.  In contrast, BE traffic receives an implied "good faith"
   commitment of at least some available network resources.  This
   document proposes a Lower Effort Differentiated Services per-domain
   behavior (LE PDB) [RFC3086] for handling this "optional" traffic in a
   differentiated services domain.

   There is no intrinsic reason to limit the applicability of the LE PDB
   to any particular application or type of traffic.  It is intended as
   an additional tool for administrators in engineering networks.

   Note: where not otherwise defined, terminology used in this document
   is defined as in [RFC2474].

2.  Applicability

   A Lower Effort (LE) PDB is for sending extremely non-critical traffic
   across a DS domain or DS region.  There should be an expectation that
   packets of the LE PDB may be delayed or dropped when other traffic is
   present.  Use of the LE PDB might assist a network operator in moving
   certain kinds of traffic or users to off-peak times.  Alternatively,
   or in addition, packets can be designated for the LE PDB when the
   goal is to protect all other packet traffic from competition with the
   LE aggregate, while not completely banning LE traffic from the
   network.  An LE PDB should not be used for a customer's "normal
   internet" traffic, nor should packets be "downgraded" to the LE PDB
   for use as a substitute for dropping packets that ought to simply be
   dropped as unauthorized.  The LE PDB is expected to be applicable to
   networks that have some unused capacity at some times of day.

   This is a PDB that allows networks to protect themselves from
   selected types of traffic rather than giving a selected traffic
   aggregate preferential treatment.  Moreover, it may also exploit all
   unused resources from other PDBs.

Bless, et al.                Informational                      [Page 2]
RFC 3662                    Lower Effort PDB               December 2003