BFD Stability
draft-ietf-bfd-stability-07

Network Working Group                                          A. Mishra
Internet-Draft                                                       SES
Intended status: Standards Track                         M. Jethanandani
Expires: July 18, 2021                                    Kloud Services
                                                               A. Saxena
                                                       Ciena Corporation
                                                           S. Pallagatti
                                                                  VmWare
                                                                 M. Chen
                                                                  Huawei
                                                                  P. Fan
                                                            China Mobile
                                                            Jan 14, 2021

                             BFD Stability
                      draft-ietf-bfd-stability-07

Abstract

   This document describes extensions to the Bidirectional Forwarding
   Detection (BFD) protocol to measure BFD stability.  Specifically, it
   describes a mechanism for detection of BFD packet loss.

Status of This Memo

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   This Internet-Draft will expire on July 18, 2021.

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   Copyright (c) 2021 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
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   3.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  BFD Null-Authentication Type  . . . . . . . . . . . . . . . .   3
   5.  Theory of Operation . . . . . . . . . . . . . . . . . . . . .   3
     5.1.  Loss Measurement  . . . . . . . . . . . . . . . . . . . .   3
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   7.  Security Consideration  . . . . . . . . . . . . . . . . . . .   4
   8.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   4
   9.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   4
   10. Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   The Bidirectional Forwarding Detection ( BFD) [RFC5880] protocol
   operates by transmitting and receiving BFD control packets, generally
   at high frequency, over the datapath being monitored.  In order to
   prevent significant data loss due to a datapath failure, BFD session
   detection time as defined in BFD [RFC5880] is set to the smallest
   feasible value.

   This document proposes a mechanism to detect lost packets in a BFD
   session in addition to the datapath fault detection mechanisms of
   BFD.  Such a mechanism presents significant value to measure the
   stability of BFD sessions and provides data to the operators for the
   cause of a BFD failure.

   This document does not propose any BFD extension to measure data
   traffic loss or delay on a link or tunnel and the scope is limited to
   BFD packets.

2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119] and
   RFC 8174 [RFC8174].

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   The reader is expected to be familiar with the BFD [RFC5880],
   Optimizing BFD Authentication
   [I-D.ietf-bfd-optimizing-authentication] and BFD Secure Sequence
   Numbers [I-D.ietf-bfd-secure-sequence-numbers].

3.  Use Cases

   Bidirectional Forwarding Detection as defined in BFD [RFC5880] cannot
   detect any BFD packet loss if the loss does not last for detection
   time.  This document proposes a method to detect a dropped packet on
   the receiver.  For example, if the receiver receives BFD control
   packet k at time t but receives packet k+3 at time t+10ms, and never
   receives packet k+1 and/or k+2, then it has experienced a drop.

   This proposal enables BFD implementations to generate diagnostic
   information on the health of each BFD session that could be used to
   preempt a failure on a datapath that BFD was monitoring by allowing
   time for a corrective action to be taken.

   In a faulty datapath scenario, an operator can use BFD health
   information to trigger delay and loss measurement OAM protocol
   (Connectivity Fault Management (CFM) or Loss Measurement (LM)-Delay
   Measurement (DM)) to further isolate the issue.

4.  BFD Null-Authentication Type

   The functionality proposed for BFD stability measurement is achieved
   by appending an authentication section with the NULL Authentication
   type (as defined in Optimizing BFD Authentication
   [I-D.ietf-bfd-optimizing-authentication] ) to the BFD control packets
   that do not have authentication enabled.

5.  Theory of Operation

   This mechanism allows operators to measure the loss of BFD control
   packets.

   When using MD5 or SHA authentication, BFD uses an authentication
   section that carries the Sequence Number.  However, if non-meticulous
   authentication is being used, or no authentication is in use, then
   the non-authenticated BFD control packets MUST include an
   authentication section with the NULL Authentication type.

5.1.  Loss Measurement

   Loss measurement counts the number of BFD control packets missed at
   the receiver during any Detection Time period.  The loss is detected
   by comparing the Sequence Number field in the Auth TLV (NULL or

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   otherwise) in successive BFD control packets.  The Sequence Number in
   each successive control packet generated on a BFD session by the
   transmitter is incremented by one.

   The first BFD authentication section with a non-zero sequence number,
   in a valid BFD control packet, processed by the receiver is used for
   bootstrapping the logic.  When using secure sequence numbers, if the
   expected values are pre-calculated, the value must be matched to
   detect lost packets as defined in BFD secure sequence numbers
   [I-D.ietf-bfd-secure-sequence-numbers].

6.  IANA Considerations

   This document has no actions for IANA.

7.  Security Consideration

   Other than concerns raised in BFD [RFC5880], Optimizing BFD
   Authentication [I-D.ietf-bfd-optimizing-authentication] and BFD
   Secure Sequence Numbers [I-D.ietf-bfd-secure-sequence-numbers].
   There are no new concerns with this proposal.

8.  Contributors

   Manav Bhatia

9.  Acknowledgements

   Authors would like to thank Nobo Akiya, Jeffery Haas, Peng Fan,
   Dileep Singh, Basil Saji, Sagar Soni and Mallik Mudigonda who also
   contributed to this document.

10.  Normative References

   [I-D.ietf-bfd-optimizing-authentication]
              Jethanandani, M., Mishra, A., Saxena, A., and M. Bhatia,
              "Optimizing BFD Authentication", draft-ietf-bfd-
              optimizing-authentication-11 (work in progress), July
              2020.

   [I-D.ietf-bfd-secure-sequence-numbers]
              Jethanandani, M., Agarwal, S., Mishra, A., Saxena, A., and
              A. DeKok, "Secure BFD Sequence Numbers", draft-ietf-bfd-
              secure-sequence-numbers-07 (work in progress), December
              2020.

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   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC5880]  Katz, D. and D. Ward, "Bidirectional Forwarding Detection
              (BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
              <https://www.rfc-editor.org/info/rfc5880>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.

Authors' Addresses

   Ashesh Mishra
   SES

   Email: mishra.ashesh@gmail.com

   Mahesh Jethanandani
   Kloud Services
   CA
   USA

   Email: mjethanandani@gmail.com

   Ankur Saxena
   Ciena Corporation
   3939 North 1st Street
   San Jose, CA  95134
   USA

   Email: ankurpsaxena@gmail.com
   URI:   www.ciena.com

   Santosh Pallagatti
   VmWare
   Bangalore, Karnataka  560103
   India

   Email: santosh.pallagatti@gmail.com

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   Mach Chen
   Huawei

   Email: mach.chen@huawei.com

   Peng Fan
   China Mobile
   32 Xuanwumen West Street
   Beijing, Beijing
   China

   Email: fanp08@gmail.com

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