Problem Statement for Service Function Chaining
RFC 7498
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
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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
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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.
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