RFC 5880 - Bidirectional Forwarding Detection (BFD)

Internet Engineering Task Force (IETF)
Request for Comments: 5880
Category: Standards Track
ISSN: 2070-1721

Authors:

• D. Katz, Juniper Networks
• D. Ward, Juniper Networks

Date: June 2010

Abstract

This document describes a protocol intended to detect faults in the bidirectional path between two forwarding engines, including interfaces, data link(s), and to the extent possible the forwarding engines themselves, with potentially very low latency. It operates independently of media, data protocols, and routing protocols.

Status of This Memo

This is an Internet Standards Track document.

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 Internet Standards is available in 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/rfc5880.

Copyright Notice

Copyright (c) 2010 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
  • 1.1. Conventions Used in This Document
• 2. Design
• 3. Protocol Overview
  • 3.1. Addressing and Session Establishment
  • 3.2. Operating Modes
• 4. BFD Control Packet Format
  • 4.1. Generic BFD Control Packet Format
  • 4.2. Simple Password Authentication Section Format
  • 4.3. Keyed MD5 and Meticulous Keyed MD5 Authentication Section Format
  • 4.4. Keyed SHA1 and Meticulous Keyed SHA1 Authentication Section Format
• 5. BFD Echo Packet Format
• 6. Elements of Procedure
  • 6.1. Overview
  • 6.2. BFD State Machine
  • 6.3. Demultiplexing and the Discriminator Fields
  • 6.4. The Echo Function and Asymmetry
  • 6.5. The Poll Sequence
  • 6.6. Demand Mode
  • 6.7. Authentication
    • 6.7.1. Enabling and Disabling Authentication
    • 6.7.2. Simple Password Authentication
    • 6.7.3. Keyed MD5 and Meticulous Keyed MD5 Authentication
    • 6.7.4. Keyed SHA1 and Meticulous Keyed SHA1 Authentication
  • 6.8. Functional Specifics
    • 6.8.1. State Variables
    • 6.8.2. Timer Negotiation
    • 6.8.3. Timer Manipulation
    • 6.8.4. Calculating the Detection Time
    • 6.8.5. Detecting Failures with the Echo Function
    • 6.8.6. Reception of BFD Control Packets
    • 6.8.7. Transmitting BFD Control Packets
    • 6.8.8. Reception of BFD Echo Packets
    • 6.8.9. Transmission of BFD Echo Packets
    • 6.8.10. Min Rx Interval Change
    • 6.8.11. Min Tx Interval Change
    • 6.8.12. Detect Multiplier Change
    • 6.8.13. Enabling or Disabling The Echo Function
    • 6.8.14. Enabling or Disabling Demand Mode
    • 6.8.15. Forwarding Plane Reset
    • 6.8.16. Administrative Control
    • 6.8.17. Concatenated Paths
    • 6.8.18. Holding Down Sessions
• 7. Operational Considerations
• 8. IANA Considerations
• 9. Security Considerations
• 10. References
  • 10.1. Normative References
  • 10.2. Informative References
• Appendix A. Backward Compatibility
• Appendix B. Contributors
• Appendix C. Acknowledgments