Architectural Guidelines for Multipath TCP Development
RFC 6182

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Internet Engineering Task Force (IETF)                           A. Ford
Request for Comments: 6182                           Roke Manor Research
Category: Informational                                        C. Raiciu
ISSN: 2070-1721                                               M. Handley
                                               University College London
                                                                S. Barre
                                        Universite catholique de Louvain
                                                              J. Iyengar
                                           Franklin and Marshall College
                                                              March 2011

         Architectural Guidelines for Multipath TCP Development

Abstract

   Hosts are often connected by multiple paths, but TCP restricts
   communications to a single path per transport connection.  Resource
   usage within the network would be more efficient were these multiple
   paths able to be used concurrently.  This should enhance user
   experience through improved resilience to network failure and higher
   throughput.

   This document outlines architectural guidelines for the development
   of a Multipath Transport Protocol, with references to how these
   architectural components come together in the development of a
   Multipath TCP (MPTCP).  This document lists certain high-level design
   decisions that provide foundations for the design of the MPTCP
   protocol, based upon these architectural requirements.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc6182.

Ford, et al.                  Informational                     [Page 1]
RFC 6182                   MPTCP Architecture                 March 2011

Copyright Notice

   Copyright (c) 2011 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
   (http://trustee.ietf.org/license-info) 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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Ford, et al.                  Informational                     [Page 2]
RFC 6182                   MPTCP Architecture                 March 2011

Table of Contents

   1. Introduction ....................................................4
      1.1. Requirements Language ......................................5
      1.2. Terminology ................................................5
      1.3. Reference Scenario .........................................6
   2. Goals ...........................................................6
      2.1. Functional Goals ...........................................6
      2.2. Compatibility Goals ........................................7
           2.2.1. Application Compatibility ...........................7
           2.2.2. Network Compatibility ...............................8
           2.2.3. Compatibility with Other Network Users .............10
      2.3. Security Goals ............................................10
      2.4. Related Protocols .........................................10
   3. An Architectural Basis for Multipath TCP .......................11
   4. A Functional Decomposition of MPTCP ............................12
   5. High-Level Design Decisions ....................................14
      5.1. Sequence Numbering ........................................14
      5.2. Reliability and Retransmissions ...........................15
      5.3. Buffers ...................................................17
      5.4. Signaling .................................................18
      5.5. Path Management ...........................................19
      5.6. Connection Identification .................................20
      5.7. Congestion Control ........................................21
      5.8. Security ..................................................21
   6. Software Interactions ..........................................23