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Versions: 00 01 02 03 04 05 draft-ietf-bfd-stability

Routing Working Group                                          A. Mishra
Internet-Draft                                         Ciena Corporation
Intended status: Standards Track                         M. Jethanandani
Expires: September 4, 2016                                 Cisco Systems
                                                               A. Saxena
                                                       Ciena Corporation
                                                           S. Pallagatti
                                                        Juniper Networks
                                                                 M. Chen
                                                                  Huawei
                                                                  P. Fan
                                                            China Mobile
                                                           March 3, 2016


                             BFD Stability
                   draft-ashesh-bfd-stability-04.txt

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 frame loss as well as
   local delay measurements for BFD transmitter and receiver.

Requirements Language

   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].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on September 4, 2016.




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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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  BFD Null-Authentication TLV . . . . . . . . . . . . . . . . .   3
   4.  Theory of Operations  . . . . . . . . . . . . . . . . . . . .   3
     4.1.  Loss Measurement  . . . . . . . . . . . . . . . . . . . .   3
     4.2.  Delay Measurement . . . . . . . . . . . . . . . . . . . .   4
   5.  IANA Requirements . . . . . . . . . . . . . . . . . . . . . .   4
   6.  Security Consideration  . . . . . . . . . . . . . . . . . . .   4
   7.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   4
   8.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   5
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   5
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

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

   This document proposes a mechanism to detect delayed or lost frames
   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 BFD extension to measure data traffic
   loss or delay on a link or tunnel and the scope is limited to BFD
   frames.



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2.  Use Cases

   Legacy BFD cannot detect any BFD frame delay or loss if delay or loss
   does not last for dead interval.  This draft proposes a method to
   distinguish between a dropped and a delayed frame on the receiver.
   For example, if the receiver receives BFD CC frame k at time t but
   receives frame k+1 at time t+9.9ms for a 3.3ms BFD interval, the
   frame is delayed.  However, if the receiver receives frame k+3 at
   time t+10ms, and never receives frame k+1 and/or k+2, then it has
   experienced a drop.  Delays can be because of congestion in the
   network or because of delays in the BFD transmitter or receiver.

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

   In a faulty datapath scenario, 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.

3.  BFD Null-Authentication TLV

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

4.  Theory of Operations

   This mechanism allows operator to measure the loss, transmitter delay
   and receiver delay of BFD CC frames.

   When using MD5 or SHA authentication, BFD uses authentication TLV
   that carries the Sequence Number.  However, if non-meticulous
   authentication is being used, or no authentication is in use, then
   the non-authenticated BFD frames MUST include NULL-Auth TLV.

4.1.  Loss Measurement

   Loss measurement counts the number of BFD control frames 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
   otherwise) in successive BFD CC frames.  The Sequence Number in each
   successive control frame generated on a BFD session by the
   transmitter is incremented by one.




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   The first BFD NULL-Auth TLV processed by the receiver that has a non-
   zero sequence number is used for bootstrapping the logic.  Each
   successive frame after this is expected to have a Sequence Number
   that is one greater than the Sequence Number in the previous frame.
   When the Sequence Number wraps around it should start from 1 instead
   of 0.

4.2.  Delay Measurement

   Delay measurement can be done locally & independently on the
   transmitter & receiver.  Hence it is out of the scope of this
   document.  Following is an example of how the delay measurement can
   be achieved on both sides:

      Transmitter Delay:

         Delay measurements on the transmitter can be made by
         calculating the time difference between software BFD engine
         transmitting the frame and the time when the hardware puts the
         frame on the wire.

      Receiver Delay:

         Delay measurement can be made using the time difference between
         the time hardware received a BFD Frame and the time software
         BFD Engine processed the frame.

   While a constant delay may not be indicator of instability, large
   transient delays can decrease the BFD session stability
   significantly.  BFD MAY choose to inform the operator about any of
   the delays when the delay measurement crosses a particular threshold
   value.

5.  IANA Requirements

   N/A

6.  Security Consideration

   Other than concerns raised in BFD [RFC5880] there are no new concerns
   with this proposal.

7.  Contributors

   Manav Bhatia






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8.  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.

9.  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-01 (work in progress), February
              2016.

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

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

Authors' Addresses

   Ashesh Mishra
   Ciena Corporation
   3939 North 1st Street
   San Jose, CA  95134
   USA

   Email: mishra.ashesh@outlook.com
   URI:   www.ciena.com


   Mahesh Jethanandani
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA  95134
   USA

   Email: mjethanandani@gmail.com
   URI:   www.cisco.com








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

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


   Santosh Pallagatti
   Juniper Networks
   Juniper Networks, Exora Business Park
   Bangalore, Karnataka  560103
   India

   Email: santoshpk@juniper.net


   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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