Services provided by IETF transport protocols and congestion control mechanisms

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Last updated 2014-12-16
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Network Working Group                                  G. Fairhurst, Ed.
Internet-Draft                                    University of Aberdeen
Intended status: Informational                          B. Trammell, Ed.
Expires: June 18, 2015                                        ETH Zurich
                                                       December 15, 2014

  Services provided by IETF transport protocols and congestion control


   This document describes services provided by existing IETF protocols
   and congestion control mechanisms.  It is designed to help
   application and network stack programmers and to inform the work of
   the IETF TAPS Working Group.

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
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   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on June 18, 2015.

Copyright Notice

   Copyright (c) 2014 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of

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   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   Most Internet applications make use of the Transport Services
   provided by TCP (a reliable, in-order stream protocol) or UDP (an
   unreliable datagram protocol).  We use the term "Transport Service"
   to mean an end-to-end facility provided by the transport layer.  That
   service can only be provided correctly if information is supplied
   from the application.  The application may determine the information
   to be supplied at design time, compile time, or run time and may
   include guidance on whether an aspect of the service is required, a
   preference by the application, or something in between.  Examples of
   Transport service facilities are reliable delivery, ordered delivery,
   content privacy to in-path devices, integrity protection, and minimal

   Transport protocols such as SCTP, DCCP, MPTCP, UDP and UDP-Lite have
   been defined at the transport layer.

   In addition, a transport service may be built on top of these
   transport protocols, using a fraemwork such as WebSockets, or RTP.
   Service built on top of UDP or UDP-Lite typically also need to
   specify a congestion control mechanism, such as TFRC or the LEDBAT
   congestion control mechanism.  This extends the set of available
   Transport Services beyond those provided to applications by TCP and

   Transport services can aslo be differentiated by the services they
   provide: for instance, SCTP offers a message-based service that does
   not suffer head-of-line blocking when used with multiple stream,
   because it can accept blocks of data out of order, UDP-Lite provides
   partial integrity protection when used over link-layer services that
   can support this, and LEDBAT can provide low-priority "scavenger"

2.  Terminology

   The following terms are defined throughout this document, and in
   subsequent documents produced by TAPS describing the composition and
   decomposition of transport services.

   The terminology below is that as was presented at the TAPS WG meeting
   in Honolulu.  While the factoring of the terminology seems
   uncontroversial, thre may be some entities which still require names
   (e.g. information about the interface between the transport and lower

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   layers which could lead to the availablity or unavailibility of
   certain transport protocol features)

   Transport Service Feature:   a specific feature a transport service
      provides to its clients end-to-end.  Examples include
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