One document matched: draft-akiya-bfd-seamless-ip-03.xml

<?xml version="1.0" encoding="US-ASCII"?>
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<rfc category="std" docName="draft-akiya-bfd-seamless-ip-03" ipr="trust200902">
  <!-- category values: std, bcp, info, exp, and historic
     ipr values: full3667, noModification3667, noDerivatives3667
     you can add the attributes updates="NNNN" and obsoletes="NNNN" 
     they will automatically be output with "(if approved)" -->

  <!-- ***** FRONT MATTER ***** -->

  <front>
    <title abbrev="Seamless BFD for IP">
	Seamless Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6 and MPLS
    </title>

    <!-- add 'role="editor"' below for the editors if appropriate -->
    <!-- Another author who claims to be an editor -->

    <author fullname="Nobo Akiya" initials="N."
            surname="Akiya">
      <organization>Cisco Systems</organization>
      <address>
        <email>nobo@cisco.com</email>
      </address>
    </author>

    <author fullname="Carlos Pignataro" initials="C."
            surname="Pignataro">
      <organization>Cisco Systems</organization>
      <address>
        <email>cpignata@cisco.com</email>
      </address>
    </author>

    <author fullname="Dave Ward" initials="D."
            surname="Ward">
      <organization>Cisco Systems</organization>
      <address>
        <email>wardd@cisco.com</email>
      </address>
    </author>

    <date year="2014" />

    <area>BFD Working Group</area>
    <workgroup>Internet Engineering Task Force</workgroup>

    <!-- WG name at the upperleft corner of the doc,
    IETF is fine for individual submissions.  
	If this element is not present, the default is "Network Working Group",
    which is used by the RFC Editor as a nod to the history of the IETF. -->

    <keyword>BFD</keyword>
    <keyword>seamless BFD</keyword>
    <keyword>negotiation free</keyword>
    <keyword>label verification</keyword>
    <keyword>segment routing</keyword>
    <keyword>IP</keyword>

    <!-- Keywords will be incorporated into HTML output
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    <abstract>
    	<t>This document defines procedures to use Seamless Bidirectional Forwarding Detection (S-BFD) for IPv4, IPv6 and MPLS environments.</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>Seamless Bidirectional Forwarding Detection (S-BFD), <xref target="I-D.ietf-bfd-seamless-base" />, defines a generalized mechanism to allow network nodes to seamlessly perform connectivity checks to remote entities. This document defines necessary procedures to use S-BFD on IPv4, IPv6 and MPLS environments.</t>

<t>The reader is expected to be familiar with the IP, MPLS BFD and S-BFD terminologies and protocol constructs.</t>

    </section>

<section title="Initiator Procedures">

<t>S-BFD packets are transmitted with IP header, UDP header and BFD control header (<xref target="RFC5880" />). When S-BFD packets are explicitly label switched, the former is prepended with a label stack. Note that this document does not make a distinction between a single-hop S-BFD scenario and a multi-hop S-BFD scenario, both scenarios are supported.</t>

<t>Necessary values in the UDP and BFD control headers are described in <xref target="I-D.ietf-bfd-seamless-base" />. <xref target="_init_pak" /> describes necessary values in the IP and MPLS headers when an SBFDInitiator on the initiator is sending S-BFD packets.</t>

<section title="Details of S-BFD Packet Sent by SBFDInitiator" anchor="_init_pak">

<t>
<list style="symbols">
  <t>Specification common to both IP routed S-BFD packets and explicitly label switched S-BFD packets:
    <list style="symbols">
    <t>Source IP address field of the IP header MUST be set to a local IP address.</t>
    </list>
  </t>
  <t>Specification for IP routed S-BFD packets:
    <list style="symbols">
    <t>Destination IP address field of the IP header MUST set to an IP address of the target.</t>
    <t>TTL field of the IP header SHOULD be set to 255.</t>
    </list>
  </t>
  <t>Specification for explicitly label switched S-BFD packets:
    <list style="symbols">
    <t>S-BFD packets MUST have the label stack that is expected to reach the target.</t>
    <t>TTL field of the top most label SHOULD be 255.</t>
    <t>Destination IP address field of the IP header MUST be set to 127/8 for IPv4 and 0:0:0:0:0:FFFF:7F00/104 for IPv6.</t>
    <t>TTL field of the IP header MUST be set to 1.</t>
    </list>
  </t>
</list>
</t>

<t>Ed-Note: Discuss whether we want a new associated channel type for S-BFD.</t>

</section>

<section title="Target vs. Remote Entity (S-BFD Discriminator)">

<t>Typically, an S-BFD packet will have "your discriminator" field corresponding to an S-BFD discriminator of the remote entity located on the target network node defined by the destination IP address or the label stack. It is, however, possible for an SBFDInitiator to carefully set "your discriminator" and TTL fields to perform a connectivity test towards a target but to a transit network node.</t>

<t><xref target="_init_pak" /> intentionally uses the word "target", instead of "remote entity", to accommodate this possible S-BFD usage through TTL expiry. This also requires S-BFD packets not be dropped by the responder node due to TTL expiry. Thus implementations on the responder MUST allow received S-BFD packets taking TTL expiry exception path to reach corresponding reflector BFD session.</t>

</section>

</section>

<section title="Responder Procedures">

<t>S-BFD packets are IP routed back to the initiator, and will have IP header, UDP header and BFD control header. Necessary values in the UDP and BFD control headers are described in <xref target="I-D.ietf-bfd-seamless-base" />. <xref target="_resp_pak" /> describes necessary values in the IP header when an SBFDReflector on the responder is sending S-BFD packets.</t>

<section title="Details of S-BFD Packet Sent by SBFDReflector" anchor="_resp_pak">

<t>
<list style="symbols">
  <t>Destination IP address field of the IP header MUST be copied from source IP address field of received S-BFD packet.</t>
  <t>Source IP address field of the IP header MUST be set to a local IP address.</t>
  <t>TTL field of the IP header SHOULD be set to 255.</t>
</list>
</t>

</section>

</section>

    <section anchor="Security" title="Security Considerations">

<t>Security considerations for S-BFD are discussed in <xref target="I-D.ietf-bfd-seamless-base" />.</t>

    </section>

    <section anchor="IANA" title="IANA Considerations">
     <t>No action is required by IANA for this document.</t>
    </section>

    <section title="Acknowledgements">

	<t>Authors would like to thank Marc Binderberger from Cisco Systems for providing valuable comments.</t>

    </section>

    <section title="Contributing Authors">

    <t>Tarek Saad
    <vspace blankLines="0" />
	Cisco Systems
    <vspace blankLines="0" />
    Email: tsaad@cisco.com</t>

	<t>Siva Sivabalan
    <vspace blankLines="0" />
	Cisco Systems
    <vspace blankLines="0" />
    Email: msiva@cisco.com</t>

	<t>Nagendra Kumar
    <vspace blankLines="0" />
	Cisco Systems
    <vspace blankLines="0" />
    Email: naikumar@cisco.com</t>

    </section>

  </middle>

  <!--  *****BACK MATTER ***** -->

  <back>
    <!-- References split into informative and normative -->

    <references title="Normative References">
	  <?rfc include="reference.RFC.2119"?>
	  <?rfc include="reference.RFC.5880"?>
       <?rfc include="reference.I-D.ietf-bfd-seamless-base"?>
    </references>

    <!-- Change Log
v00-a 2013-05-20 Nobo: Initial version
v00-b 2013-05-24 Nobo: Included comments from Carlos/Nagendra
v00-c 2013-05-27 Nobo: Incorporated comments from Marc
v01-a 2013-12-04 Nobo: Minor tweak to keep draft alive
v03-a 2014-06-24 Nobo: Major rewrite to align with new base
    -->
  </back>
</rfc>