Problem Statement for Service Function Chaining
RFC 7498

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Internet Engineering Task Force (IETF)                     P. Quinn, Ed.
Request for Comments: 7498                           Cisco Systems, Inc.
Category: Informational                                   T. Nadeau, Ed.
ISSN: 2070-1721                                                  Brocade
                                                              April 2015

            Problem Statement for Service Function Chaining

Abstract

   This document provides an overview of the issues associated with the
   deployment of service functions (such as firewalls, load balancers,
   etc.) in large-scale environments.  The term "service function
   chaining" is used to describe the definition and instantiation of an
   ordered list of instances of such service functions, and the
   subsequent "steering" of traffic flows through those service
   functions.

   The set of enabled service function chains reflects operator service
   offerings and is designed in conjunction with application delivery
   and service and network policy.

   This document also identifies several key areas that the Service
   Function Chaining (SFC) working group will investigate to guide its
   architectural and protocol work and associated documents.

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/rfc7498.

Quinn & Nadeau                Informational                     [Page 1]
RFC 7498                  SFC Problem Statement               April 2015

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
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   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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Definition of Terms . . . . . . . . . . . . . . . . . . .   3
   2.  Problem Space . . . . . . . . . . . . . . . . . . . . . . . .   5
     2.1.  Topological Dependencies  . . . . . . . . . . . . . . . .   5
     2.2.  Configuration Complexity  . . . . . . . . . . . . . . . .   6
     2.3.  Constrained High Availability . . . . . . . . . . . . . .   6
     2.4.  Consistent Ordering of Service Functions  . . . . . . . .   6
     2.5.  Application of Service Policy . . . . . . . . . . . . . .   6
     2.6.  Transport Dependence  . . . . . . . . . . . . . . . . . .   7
     2.7.  Elastic Service Delivery  . . . . . . . . . . . . . . . .   7
     2.8.  Traffic Selection Criteria  . . . . . . . . . . . . . . .   7
     2.9.  Limited End-to-End Service Visibility . . . . . . . . . .   7
     2.10. Classification/Reclassification per Service Function  . .   7
     2.11. Symmetric Traffic Flows . . . . . . . . . . . . . . . . .   8
     2.12. Multi-vendor Service Functions  . . . . . . . . . . . . .   8
   3.  Service Function Chaining . . . . . . . . . . . . . . . . . .   8
     3.1.  Service Overlay . . . . . . . . . . . . . . . . . . . . .   8
     3.2.  Service Classification  . . . . . . . . . . . . . . . . .   9
     3.3.  SFC Encapsulation . . . . . . . . . . . . . . . . . . . .   9
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .  10
   5.  Informative References  . . . . . . . . . . . . . . . . . . .  11
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  11
   Contributors  . . . . . . . . . . . . . . . . . . . . . . . . . .  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  13

Quinn & Nadeau                Informational                     [Page 2]
RFC 7498                  SFC Problem Statement               April 2015

1.  Introduction

   The delivery of end-to-end services often requires various service
   functions including traditional network service functions (for
   example, firewalls and server load balancers), as well as
   application-specific features such as HTTP header manipulation.