Seamless Bidirectional Forwarding Detection (S-BFD) Use Cases
RFC 7882

Document Type RFC - Informational (July 2016; No errata)
Last updated 2018-12-20
Replaces draft-aldrin-bfd-seamless-use-case
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Document shepherd Jeffrey Haas
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IESG IESG state RFC 7882 (Informational)
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Responsible AD Alvaro Retana
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Internet Engineering Task Force (IETF)                         S. Aldrin
Request for Comments: 7882                                  Google, Inc.
Category: Informational                                     C. Pignataro
ISSN: 2070-1721                                                    Cisco
                                                               G. Mirsky
                                                                Ericsson
                                                                N. Kumar
                                                                   Cisco
                                                               July 2016

     Seamless Bidirectional Forwarding Detection (S-BFD) Use Cases

Abstract

   This document describes various use cases for Seamless Bidirectional
   Forwarding Detection (S-BFD) and provides requirements such that
   protocol mechanisms allow for simplified detection of forwarding
   failures.

   These use cases support S-BFD, which is a simplified mechanism for
   using BFD with a large proportion of negotiation aspects eliminated,
   accelerating the establishment of a BFD session.  The benefits of
   S-BFD include quick provisioning, as well as improved control and
   flexibility for network nodes initiating path monitoring.

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 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/rfc7882.

Aldrin, et al.                Informational                     [Page 1]
RFC 7882                     S-BFD Use Cases                   July 2016

Copyright Notice

   Copyright (c) 2016 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.

Table of Contents

   1. Introduction ....................................................3
      1.1. Terminology ................................................3
   2. Introduction to Seamless BFD ....................................4
   3. Use Cases .......................................................5
      3.1. Unidirectional Forwarding Path Validation ..................5
      3.2. Validation of the Forwarding Path prior to
           Switching Traffic ..........................................6
      3.3. Centralized Traffic Engineering ............................7
      3.4. BFD in Centralized Segment Routing .........................8
      3.5. Efficient BFD Operation under Resource Constraints .........8
      3.6. BFD for Anycast Addresses ..................................8
      3.7. BFD Fault Isolation ........................................9
      3.8. Multiple BFD Sessions to the Same Target Node ..............9
      3.9. An MPLS BFD Session per ECMP Path .........................10
   4. Detailed Requirements for Seamless BFD .........................11
   5. Security Considerations ........................................12
   6. References .....................................................12
      6.1. Normative References ......................................12
      6.2. Informative References ....................................13
   Acknowledgements ..................................................15
   Contributors ......................................................15
   Authors' Addresses ................................................15

Aldrin, et al.                Informational                     [Page 2]
RFC 7882                     S-BFD Use Cases                   July 2016

1.  Introduction

   Bidirectional Forwarding Detection (BFD), as defined in [RFC5880], is
   a lightweight protocol used to detect forwarding failures.  Various
   protocols, applications, and clients rely on BFD for failure
   detection.  Even though the protocol is lightweight and simple, there
   are certain use cases where faster setup of sessions and faster
   continuity checks of the data-forwarding paths are necessary.  This
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