Software-Defined Networking (SDN): Layers and Architecture Terminology
RFC 7426

Document Type RFC - Informational (January 2015; No errata)
Last updated 2015-01-07
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Internet Research Task Force (IRTF)                   E. Haleplidis, Ed.
Request for Comments: 7426                          University of Patras
Category: Informational                              K. Pentikousis, Ed.
ISSN: 2070-1721                                                     EICT
                                                              S. Denazis
                                                    University of Patras
                                                           J. Hadi Salim
                                                       Mojatatu Networks
                                                                D. Meyer
                                                                 Brocade
                                                          O. Koufopavlou
                                                    University of Patras
                                                            January 2015

 Software-Defined Networking (SDN): Layers and Architecture Terminology

Abstract

   Software-Defined Networking (SDN) refers to a new approach for
   network programmability, that is, the capacity to initialize,
   control, change, and manage network behavior dynamically via open
   interfaces.  SDN emphasizes the role of software in running networks
   through the introduction of an abstraction for the data forwarding
   plane and, by doing so, separates it from the control plane.  This
   separation allows faster innovation cycles at both planes as
   experience has already shown.  However, there is increasing confusion
   as to what exactly SDN is, what the layer structure is in an SDN
   architecture, and how layers interface with each other.  This
   document, a product of the IRTF Software-Defined Networking Research
   Group (SDNRG), addresses these questions and provides a concise
   reference for the SDN research community based on relevant peer-
   reviewed literature, the RFC series, and relevant documents by other
   standards organizations.

Haleplidis, et al.            Informational                     [Page 1]
RFC 7426        SDN: Layers and Architecture Terminology    January 2015

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 Research Task Force
   (IRTF).  The IRTF publishes the results of Internet-related research
   and development activities.  These results might not be suitable for
   deployment.  This RFC represents the consensus of the Software-
   Defined Networking Research Group of the Internet Research Task Force
   (IRTF).  Documents approved for publication by the IRSG are not 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/rfc7426.

Copyright Notice

   Copyright (c) 2015 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.

Haleplidis, et al.            Informational                     [Page 2]
RFC 7426        SDN: Layers and Architecture Terminology    January 2015

Table of Contents

   1. Introduction ....................................................4
   2. Terminology .....................................................5
   3. SDN Layers and Architecture .....................................7
      3.1. Overview ...................................................9
      3.2. Network Devices ...........................................12
      3.3. Control Plane .............................................13
      3.4. Management Plane ..........................................14
      3.5. Discussion of Control and Management Planes ...............16
           3.5.1. Timescale ..........................................16
           3.5.2. Persistence ........................................16
           3.5.3. Locality ...........................................16
           3.5.4. CAP Theorem Insights ...............................17
      3.6. Network Services Abstraction Layer ........................18
      3.7. Application Plane .........................................19
   4. SDN Model View .................................................19
      4.1. ForCES ....................................................19
      4.2. NETCONF/YANG ..............................................20
      4.3. OpenFlow ..................................................21
      4.4. Interface to the Routing System ...........................21
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