Bidirectional Forwarding Detection (BFD) on Link Aggregation Group (LAG) Interfaces
RFC 7130

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Internet Engineering Task Force (IETF)                    M. Bhatia, Ed.
Request for Comments: 7130                                Alcatel-Lucent
Category: Standards Track                                   M. Chen, Ed.
ISSN: 2070-1721                                      Huawei Technologies
                                                         S. Boutros, Ed.
                                                    M. Binderberger, Ed.
                                                           Cisco Systems
                                                            J. Haas, Ed.
                                                        Juniper Networks
                                                           February 2014

              Bidirectional Forwarding Detection (BFD) on
                Link Aggregation Group (LAG) Interfaces

Abstract

   This document defines a mechanism to run Bidirectional Forwarding
   Detection (BFD) on Link Aggregation Group (LAG) interfaces.  It does
   so by running an independent Asynchronous mode BFD session on every
   LAG member link.

   This mechanism allows the verification of member link continuity,
   either in combination with, or in absence of, Link Aggregation
   Control Protocol (LACP).  It provides a shorter detection time than
   what LACP offers.  The continuity check can also cover elements of
   Layer 3 (L3) bidirectional forwarding.

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/rfc7130.

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RFC 7130                 BFD for LAG Interfaces            February 2014

Copyright Notice

   Copyright (c) 2014 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  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
   2.  BFD on LAG Member Links . . . . . . . . . . . . . . . . . . .   3
     2.1.  Micro-BFD Session Address Family  . . . . . . . . . . . .   4
     2.2.  Micro-BFD Session Negotiation . . . . . . . . . . . . . .   4
     2.3.  Micro-BFD Session Ethernet Details  . . . . . . . . . . .   5
   3.  Interaction between LAG and BFD . . . . . . . . . . . . . . .   6
   4.  BFD on LAG Member Links and L3 Applications . . . . . . . . .   6
   5.  Detecting a Member Link Failure . . . . . . . . . . . . . . .   6
   6.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   9.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     10.1.  Normative References . . . . . . . . . . . . . . . . . .   9
     10.2.  Informative References . . . . . . . . . . . . . . . . .   9
   Appendix A.  Considerations When Using BFD on Member Links  . . .  10

1.  Introduction

   The Bidirectional Forwarding Detection (BFD) protocol [RFC5880]
   provides a mechanism to detect faults in the bidirectional path
   between two forwarding engines, including interfaces, data links, and
   to the extent possible the forwarding engines themselves, with
   potentially very low latency.  The BFD protocol also provides a fast
   mechanism for detecting communication failures on any data links and
   the protocol can run over any media and at any protocol layer.

   LAG, as defined in [IEEE802.1AX], provides mechanisms to combine
   multiple physical links into a single logical link.  This logical
   link provides higher bandwidth and better resiliency, because if one

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RFC 7130                 BFD for LAG Interfaces            February 2014

   of the physical member links fails, the aggregate logical link can