Network Transport Circuit Breakers
RFC 8084

Document Type RFC - Best Current Practice (March 2017; No errata)
Also known as BCP 208
Last updated 2017-03-07
Replaces draft-fairhurst-tsvwg-circuit-breaker
Stream IETF
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Stream WG state Submitted to IESG for Publication Dec 2015
Document shepherd David Black
Shepherd write-up Show (last changed 2015-09-28)
IESG IESG state RFC 8084 (Best Current Practice)
Consensus Boilerplate Yes
Telechat date
Responsible AD Spencer Dawkins
Send notices to (None)
IANA IANA review state Version Changed - Review Needed
IANA action state No IC
Internet Engineering Task Force (IETF)                      G. Fairhurst
Request for Comments: 8084                        University of Aberdeen
BCP: 208                                                      March 2017
Category: Best Current Practice
ISSN: 2070-1721

                   Network Transport Circuit Breakers

Abstract

   This document explains what is meant by the term "network transport
   Circuit Breaker".  It describes the need for Circuit Breakers (CBs)
   for network tunnels and applications when using non-congestion-
   controlled traffic and explains where CBs are, and are not, needed.
   It also defines requirements for building a CB and the expected
   outcomes of using a CB within the Internet.

Status of This Memo

   This memo documents an Internet Best Current Practice.

   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).  Further information on
   BCPs is available in Section 2 of RFC 7841.

   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/rfc8084.

Copyright Notice

   Copyright (c) 2017 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.

Fairhurst                 Best Current Practice                 [Page 1]
RFC 8084                                                      March 2017

Table of Contents

   1. Introduction ....................................................2
      1.1. Types of CBs ...............................................5
   2. Terminology .....................................................6
   3. Design of a CB (What makes a good CB?) ..........................6
      3.1. Functional Components ......................................6
      3.2. Other Network Topologies ...................................9
           3.2.1. Use with a Multicast Control/Routing Protocol ......10
           3.2.2. Use with Control Protocols Supporting
                  Pre-provisioned Capacity ...........................11
           3.2.3. Unidirectional CBs over Controlled Paths ...........11
   4. Requirements for a Network Transport CB ........................12
   5. Examples of CBs ................................................15
      5.1. A Fast-Trip CB ............................................15
           5.1.1. A Fast-Trip CB for RTP .............................16
      5.2. A Slow-Trip CB ............................................16
      5.3. A Managed CB ..............................................17
           5.3.1. A Managed CB for SAToP Pseudowires .................17
           5.3.2. A Managed CB for Pseudowires (PWs) .................18
   6. Examples in Which CBs May Not Be Needed ........................19
      6.1. CBs over Pre-provisioned Capacity .........................19
      6.2. CBs with Tunnels Carrying Congestion-Controlled Traffic ...19
      6.3. CBs with Unidirectional Traffic and No Control Path .......20
   7. Security Considerations ........................................20
   8. References .....................................................22
      8.1. Normative References ......................................22
      8.2. Informative References ....................................22
   Acknowledgments ...................................................24
   Author's Address ..................................................24

1.  Introduction

   The term "Circuit Breaker" originates in electricity supply, and has
   nothing to do with network circuits or virtual circuits.  In
   electricity supply, a Circuit Breaker (CB) is intended as a
   protection mechanism of last resort.  Under normal circumstances, a
   CB ought not to be triggered; it is designed to protect the supply
   network and attached equipment when there is overload.  People do not
   expect an electrical CB (or fuse) in their home to be triggered,
   except when there is a wiring fault or a problem with an electrical
   appliance.

   In networking, the CB principle can be used as a protection mechanism
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