One document matched: draft-ashesh-bfd-stability-04.xml

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<rfc category="std" docName="draft-ashesh-bfd-stability-04.txt"
     ipr="trust200902">
  <front>
    <title abbrev="BFD Stability">BFD Stability</title>

    <author fullname="Ashesh Mishra" initials="A" surname="Mishra">
      <organization>Ciena Corporation</organization>

      <address>
        <postal>
          <street>3939 North 1st Street</street>

          <city>San Jose</city>

          <region>CA</region>

          <code>95134</code>

          <country>USA</country>
        </postal>

        <phone/>

        <email>mishra.ashesh@outlook.com</email>

        <uri>www.ciena.com</uri>
      </address>
    </author>

    <author fullname="Mahesh Jethanandani" initials="M" surname="Jethanandani">
      <organization>Cisco Systems</organization>

      <address>
        <postal>
          <street>170 W. Tasman Drive</street>

          <city>San Jose</city>

          <region>CA</region>

          <code>95134</code>

          <country>USA</country>
        </postal>

        <phone/>

        <facsimile/>

        <email>mjethanandani@gmail.com</email>

        <uri>www.cisco.com</uri>
      </address>
    </author>

    <author fullname="Ankur Saxena" initials="A" surname="Saxena">
      <organization>Ciena Corporation</organization>

      <address>
        <postal>
          <street>3939 North 1st Street</street>

          <city>San Jose</city>

          <region>CA</region>

          <code>95134</code>

          <country>USA</country>
        </postal>

        <phone/>

        <facsimile/>

        <email>ankurpsaxena@gmail.com</email>

        <uri>www.ciena.com</uri>
      </address>
    </author>

    <author fullname="Santosh Pallagatti" initials="S" surname="Pallagatti">
      <organization>Juniper Networks</organization>

      <address>
        <postal>
          <street>Juniper Networks, Exora Business Park</street>

          <city>Bangalore</city>

          <region>Karnataka</region>

          <code>560103</code>

          <country>India</country>
        </postal>

        <phone/>

        <facsimile/>

        <email>santoshpk@juniper.net</email>

        <uri/>
      </address>
    </author>

    <author fullname="Mach Chen" initials="M" surname="Chen">
      <organization>Huawei</organization>

      <address>
        <postal>
          <street/>

          <city/>

          <region/>

          <code/>

          <country/>
        </postal>

        <phone/>

        <facsimile/>

        <email>mach.chen@huawei.com</email>

        <uri/>
      </address>
    </author>

    <author fullname="Peng Fan" initials="P." surname="Fan">
      <organization>China Mobile</organization>

      <address>
        <postal>
          <street>32 Xuanwumen West Street</street>

          <city>Beijing</city>

          <region>Beijing</region>

          <country>China</country>
        </postal>

        <email>fanp08@gmail.com</email>
      </address>
    </author>

    <date day="3" month="March" year="2016"/>

    <area>Network</area>

    <workgroup>Routing Working Group</workgroup>

    <keyword>Internet-Draft</keyword>

    <abstract>
      <t>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.</t>
    </abstract>

    <note title="Requirements Language">
      <t>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 <xref
      target="RFC2119">RFC 2119</xref>.</t>
    </note>
  </front>

  <middle>
    <section title="Introduction">
      <t>The Bidirectional Forwarding Detection (<xref
      target="RFC5880">BFD)</xref> 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 <xref target="RFC5880">BFD</xref> is set
      to the smallest feasible value.</t>

      <t>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.</t>

      <t>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.</t>
    </section>

    <section title="Use Cases">
      <t>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.</t>

      <t>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.</t>

      <t>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.</t>
    </section>

    <section title="BFD Null-Authentication TLV">
      <t>The functionality proposed for BFD stability measurement is achieved
      by appending the Null-Authentication TLV (as defined in <xref
      target="I-D.ietf-bfd-optimizing-authentication">Optimizing BFD
      Authentication</xref> ) to the BFD control frame that do not have
      authentication enabled.</t>
    </section>

    <section title="Theory of Operations">
      <t>This mechanism allows operator to measure the loss, transmitter delay
      and receiver delay of BFD CC frames.</t>

      <t>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.</t>

      <section title="Loss Measurement">
        <t>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.</t>

        <t>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.</t>
      </section>

      <section title="Delay Measurement">
        <t>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:<list style="empty">
            <t>Transmitter Delay: <list style="empty">
                <t>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.</t>
              </list></t>
          </list><list style="empty">
            <t>Receiver Delay: <list style="empty">
                <t>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.</t>
              </list></t>
          </list></t>

        <t>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.</t>
      </section>
    </section>

    <section title="IANA Requirements">
      <t>N/A</t>
    </section>

    <section title="Security Consideration">
      <t>Other than concerns raised in <xref target="RFC5880">BFD</xref> there
      are no new concerns with this proposal.</t>
    </section>

    <section title="Contributors">
      <t><figure>
          <artwork><![CDATA[
Manav Bhatia]]></artwork>
        </figure></t>
    </section>

    <section title="Acknowledgements">
      <t>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.</t>
    </section>
  </middle>

  <back>
    <references title="Normative References">
      <?rfc include='reference.RFC.5880'?>

      <?rfc include='reference.RFC.2119'?>

      <?rfc include='reference.I-D.ietf-bfd-optimizing-authentication'?>
    </references>
  </back>
</rfc>