One document matched: draft-tantsura-idr-bgp-ls-segment-routing-msd-01.xml

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<!ENTITY I-D.ietf-pce-segment-routing SYSTEM "http://xml2rfc.ietf.org/public/rfc/bibxml3/reference.I-D.draft-ietf-pce-segment-routing-06.xml">

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<rfc category="std" ipr="trust200902" docName="draft-tantsura-idr-bgp-ls-segment-routing-msd-01">

<?xml-stylesheet type='text/xsl' href='rfc2629.xslt' ?>

<front>
	<title abbrev='Signaling MSD Using BGP-LS'>Signaling Maximum
	SID Depth using Border Gateway Protocol Link-State</title>

	<author initials='J.' surname="Tantsura" fullname='Jeff  Tantsura'>
		<organization>Individual</organization>
		<address>
			<email>jefftant.ietf@gmail.com</email>
		</address> 
	</author>
	<author initials='G.' surname="Mirsky" fullname='Greg Mirsky'>
		<organization>Ericsson</organization>
		<address>
			<email>gregory.mirsky@ericsson.com</email>
		</address> 
	</author>
 	<author initials='S.' surname="Sivabalan" fullname='Siva Sivabalan'>
		<organization>Cisco</organization>
		<address>
			<email>msiva@cisco.com</email>
		</address> 
	</author>
	<author initials='U.' surname="Chunduri" fullname='Uma Chunduri'>
		<organization>Ericsson</organization>
		<address>
		  <email>uma.chunduri@ericsson.com</email>
		</address> 
	</author>
    <date day="8" month="July" year="2016" />

    <area>Routing</area>

    <workgroup>IDR Working Group</workgroup>

    <keyword>Internet-Draft</keyword>

    <keyword>BGP-LS</keyword>
    
    <keyword>SID</keyword>
   
   <keyword>MSD </keyword>
	
	<abstract>
	<t>
      	This document discusses use of BGP-LS to expose node and/or
	link on a node MSD  "Maximum SID Depth" to a centralized controller (PCE/SDN).
	 </t>
	</abstract>
</front>

<middle>
  <section anchor="intro" title="Introduction">
 <t>
    When Segment Routing tunnels are computed by a centralized
      controller, it is crucial that the controller knows
      MSD "Maximum SID Depth" of the node or link SR tunnel exits over, so it doesn't
      download a path with SID (label stack) of a depth more than
      the node or link configured is capable of imposing.This document
      describes how to use  BGP-LS to expose the MSD of the node or link configured to a centralized
      controller.
 </t>
         
 <section title="Conventions used in this document">
   <section title="Terminology">

    <t>BGP-LS: Distribution of Link-State and TE
	    Information using Border Gateway Protocol </t>

    <t>MSD: Maximum SID Depth </t>

   <t> PCC:  Path Computation Client </t>

   <t> PCE:  Path Computation Element </t>

   <t> PCEP:  Path Computation Element Protocol </t>

   <t> SID:  Segment Identifier </t>

   <t> SR:  Segment routing </t>
   
         </section>    
         
        <section title="Requirements Language">
             <t>
	  The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
                "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 
	  "OPTIONAL" in this document are to be interpreted as described in 
	  <xref target="RFC2119"></xref>.
             </t>
          </section>
      </section>
     </section>
      
     <section anchor="problem-statement" title="Problem Statement">
     
<t>
In existing technology only PCEP has extension to signal the MSD (SR
PCE Capability TLV/ METRIC Object as defined in
<xref target="I-D.ietf-pce-segment-routing"></xref>,If PCEP is not
supported by the node  (head-end of the SR tunnel) controller has no
way to learn the MSD of the node/link configured.
OSPF and IS-IS extensions are defined in:</t>
<t><xref target="I-D.tantsura-ospf-segment-routing-msd"></xref></t>
<t><xref target="I-D.tantsura-isis-segment-routing-msd"></xref></t>

     </section>
     
     <section anchor="NodeMSD"  title="MSD supported by a node">
 <t>Node MSD is encoded in a new Node Attribute TLV, as defined in <xref target="RFC7752"></xref> </t>


            <figure anchor="node-attribute_tlv" title="Node attribute format">
              <artwork>
   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |              Type             |             Length            | 
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     MSD       |  
  +-+-+-+-+-+-+-+-+
	         </artwork>
            </figure>
	    <t> Type :  A 2-octet field specifiying code-point of the new
             TLV type. Code-point: TBA (suggested 1050) from BGP-LS
	     Node Descriptor, Link Descriptor, Prefix Descriptor, and
	     Attribute TLVs registry </t>
	     <t>Length: A 2-octet field that indicates the length of the
	     value portion </t>
	     <t>MSD: Node MSD is a number in the range of 0-254. The vaule of 0 represents lack of ability to push MSD of any depth, any other value represents
            that of the node.</t>
 </section>	  
	  <section anchor="LinkMSD" title="MSD supported on a link">
      <t>Link MSD is encoded in a New Link Attribute TLV,
      as defined in <xref target="RFC7752"></xref></t>

            <figure anchor="link-attribute_tlv" title="Link attribute format">
              <artwork>
   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |              Type             |             Length            | 
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |     MSD       |  
  +-+-+-+-+-+-+-+-+
              </artwork>
            </figure>

	    <t> Type :  A 2-octet field specifiying code-point of the new
             TLV type. Code-point: TBA (suggested 1110) from BGP-LS
	     Node Descriptor, Link Descriptor, Prefix Descriptor, and
	     Attribute TLVs registry </t>

	     <t>Length: A 2-octet field that indicates the length of the
	     value portion </t>
	     <t>MSD: Link MSD is a number in the range of 0-254. The vaule of 0 represents lack of ability to push MSD of any depth, any other value represents
            that of the link.</t>
          </section>
     <section anchor="iana-consider" title="IANA Considerations">
     <t>
   This document requests assigning 2 new code-points from the BGP-LS
   Node Descriptor, Link Descriptor, Prefix Descriptor, and Attribute
   TLVs  registry as specified in sections 3 and 4.
 </t>
    </section>
     
     <section anchor="security" title="Security Considerations">
     <t>
       This document does not introduce security issues beyond those
       discussed in <xref target="RFC7752"></xref>
     </t>
     </section>
      
     
      <section title="Acknowledgements">
        <t>
	  We like to thank Nikos Triantafillis for the valuable comments.
         </t>  
      </section>

  </middle>
  
    <back>
    <references title="Normative References">

      &RFC2119;
      &RFC7752;
    <?rfc include='reference.I-D.ietf-spring-segment-routing-mpls'?>
    <?rfc include='reference.I-D.ietf-pce-segment-routing'?>
    <?rfc include='reference.I-D.tantsura-isis-segment-routing-msd'?>
    <?rfc include='reference.I-D.tantsura-ospf-segment-routing-msd'?>
    </references>
<references title="Informative References">

      <?rfc include="reference.I-D.ietf-isis-segment-routing-extensions"?>
      <?rfc include="reference.I-D.ietf-ospf-segment-routing-extensions"?>
    </references>

 </back>
 </rfc>