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<rfc xmlns:xi="http://www.w3.org/2001/XInclude" number="8668"
docName="draft-ietf-isis-l2bundles-07" category="std" docName="draft-ietf-isis-l2bundles-07.txt"
     ipr="trust200902">
submissionType="IETF" consensus="true" ipr="trust200902"
tocInclude="true" symRefs="true" sortRefs="true"
xml:lang="en" version="3">

  <front>
    <title abbrev="isis-l2bundles">Advertising abbrev="Advertising L2 Bundle Attributes in IS-IS">Advertising Layer 2 Bundle Member Link
    Attributes in IS-IS</title>
<seriesInfo name="RFC" value="8668"/>
    <author fullname="Les Ginsberg" initials="L" surname="Ginsberg"> surname="Ginsberg" role="editor">
      <organization>Cisco Systems</organization> Systems, Inc.</organization>

      <address>
        <postal>
          <street>510 McCarthy Blvd.</street>

          <city>Milpitas</city>

          <code>95035</code>

          <region>CA</region>

          <country>USA</country>
          <street></street>

          <city></city>

          <code></code>

          <region></region>

          <country></country>
        </postal>

        <email>ginsberg@cisco.com</email>
      </address>
    </author>

    <author fullname="Ahmed Bashandy" initials="A" surname="Bashandy">
      <organization>Cisco Systems</organization>
      <organization>Unaffiliated</organization>

      <address>
        <postal>
          <street>170 West Tasman Drive</street>

          <city>San Jose</city>

          <code>95134</code>

          <region>Ca</region>

          <country>US</country>

          <country>United States of America</country>
        </postal>
<email>abashandy.ietf@gmail.com
</email>
      </address>
    </author>

    <author fullname="Clarence Filsfils" initials="C" surname="Filsfils">
      <organization>Cisco Systems</organization> Systems, Inc.</organization>

      <address>
        <postal>
          <street/>

          <city/>

          <code/>

          <region/>

          <country/>
        </postal>

        <email>cf@cisco.com</email>
      </address>
    </author>

    <author fullname="Mohan Nanduri" initials="M" surname="Nanduri">
      <organization>eBay</organization>
      <organization>Oracle</organization>

      <address>
        <postal>
          <street/>

          <city/>

          <code/>

          <country/>
        </postal>

        <email>mnanduri@ebay.com</email>

        <email>mohan.nanduri@oracle.com</email>
      </address>
    </author>

    <author fullname="Ebben Aries" initials="E" surname="Aries">
      <organization>Private Contributer</organization>
      <organization>Arrcus Inc.</organization>

      <address>
        <postal>
          <street/>

          <city/>

          <code/>

          <country/>
          <street>2077 Gateway Place, Suite #400</street>
          <city>San Jose</city>
          <code>95119
	  </code>
<region>CA</region>
          <country>United States of America
	  </country>
        </postal>

        <email>exa@dscp.org</email>

        <email>exa@arrcus.com</email>
      </address>
    </author>

    <date day="25" month="May" year="2017"/>

    <area>Routing Area</area>

    <workgroup>Networking Working Group</workgroup>

    <keyword>Sample</keyword> month="December" year="2019"/>

    <abstract>
      <t>There are deployments where the Layer 3 interface on which IS-IS
      operates is a Layer 2 interface bundle. Existing IS-IS advertisements
      only support advertising link attributes of the Layer 3 interface. If
      entities external to IS-IS wish to control traffic flows on the
      individual physical links which that comprise the Layer 2 interface bundle bundle,
      link attribute information about the bundle members is required.</t>

      <t>This document introduces the ability for IS-IS to advertise the link
      attributes of layer Layer 2 (L2) bundle members.</t> Bundle Members.</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 RFC 2119 [RFC2119].</t>
    </note>

  </front>

  <middle>
    <section title="Introduction">
    <section>
    <name>Introduction</name>
      <t>There are deployments where the Layer 3 interface on which an IS-IS
      adjacency is established is a Layer 2 interface bundle, for instance instance, a
      Link Aggregation Group (LAG) [IEEE802.1AX]. <xref target="IEEE802.1AX"/>. This reduces the number of
      adjacencies which that need to be maintained by the routing protocol in cases
      where there are parallel links between the neighbors. Entities external
      to IS-IS such as Path Computation Elements (PCE) [RFC4655] (PCEs) <xref target="RFC4655"/> may wish to
      control traffic flows on individual members of the underlying Layer 2
      bundle. In order to do so so, link attribute information about individual
      bundle members is required. The protocol extensions defined in this
      document provide the means to advertise this information.</t>

      <t>This document introduces a new TLV to advertise link attribute
      information for each of the L2 bundle members which Bundle Members that comprise the Layer 3
      interface on which IS-IS operates.</t>

      <t>[SR-ISIS]

      <t><xref target="RFC8667"/> introduces a new link attribute - attribute, adjacency segment
      identifier (Adj-SID) - (Adj-SID), which can be used as an instruction to forwarding
      to send traffic over a specific link. This document introduces
      additional sub-TLVs to advertise Adj-SIDs for L2 Bundle members.</t> Members.</t>

      <t>Note that the new advertisements defined in this document are
      intended to be provided to external (to IS-IS) entities. The following
      items are intentionally not defined and/or are outside the scope of this
      document:</t>

      <t><list style="symbols">
          <t>What

      <ul>
          <li>What link attributes will be advertised. This is determined by
          the needs of the external entities.</t>

          <t>A entities.</li>

          <li>A minimum or default set of link attributes.</t>

          <t>How attributes.</li>

          <li>How these attributes are configured</t>

          <t>How configured.</li>

          <li>How the advertisements are used</t>

          <t>What used.</li>

          <li>What impact the use of these advertisements may have on traffic
          flow in the network</t>

          <t>How network.</li>

          <li>How the advertisements are passed to external entities</t>
        </list></t> entities.</li>
        </ul>
    </section>

    <section>
    <name>Requirements Language</name>
         <t>
    The key words "<bcp14>MUST</bcp14>", "<bcp14>MUST NOT</bcp14>", "<bcp14>REQUIRED</bcp14>", "<bcp14>SHALL</bcp14>", "<bcp14>SHALL
    NOT</bcp14>", "<bcp14>SHOULD</bcp14>", "<bcp14>SHOULD NOT</bcp14>", "<bcp14>RECOMMENDED</bcp14>", "<bcp14>NOT RECOMMENDED</bcp14>",
    "<bcp14>MAY</bcp14>", and "<bcp14>OPTIONAL</bcp14>" in this document are to be interpreted as
    described in BCP&nbsp;14 <xref target="RFC2119"/> <xref target="RFC8174"/>
    when, and only when, they appear in all capitals, as shown here.
        </t>
    </section>

    <section title="L2 anchor="BUNDLE">
    <name>L2 Bundle Member Attributes TLV"> TLV</name>
      <t>A new TLV is introduced to advertise L2 Bundle member Member attributes.
      Although much of the information is identical to and uses the same
      sub-TLVs included in Extended IS-Neighbor IS Neighbor advertisements (TLVs 22 and
      222), a new TLV is used so that changes to the advertisement of the L2
      Bundle member Member link attributes does do not trigger unnecessary action by the
      [ISO10589]
      <xref target="ISO10589"/> Decision process.</t> Process.</t>

      <t>Advertisement of this information implies that the identified link is
      a member of the L2 Bundle associated with the identified Parent L3
      Neighbor and that the member link is operationally up. Therefore Therefore,
      advertisements MUST <bcp14>MUST</bcp14> be withdrawn if the link becomes operationally down
      or it is no longer a member of the identified L2 Bundle.</t>

      <t>This new TLV utilizes the sub-TLV space defined for TLVs 22, 23, 141,
      222, and 223.</t>

      <t>The following new TLV is introduced:</t>

      <t><figure>
          <artwork><![CDATA[    L2

  <ul empty="true" spacing="normal">
<li>L2 Bundle Member Attributes
    Type:
</li>
<li>Type: 25 (suggested - to be assigned by IANA)
    Length:
</li>
<li>Length: Number of octets to follow

    Parent
</li>

</ul>

<ul empty="true" spacing="normal">
   <li>Parent L3 Neighbor Descriptor
     L3
   </li>
   <li>
      <ul empty="true">
         <li>L3 Neighbor System ID + pseudonode ID (7 octets)
     Flags: 1 octet
         </li>
      </ul>
      <ul empty="true">
         <li>
            <dl spacing="compact">
               <dt>Flags:</dt><dd>1-octet field of the following flags: flags:</dd>
             </dl>
         </li>
      </ul>

<ul empty="true"><li>

      <ul empty="true" spacing="compact">
        <li>

  <artwork name="" type="" align="left" alt=""><![CDATA[ 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|P|             |
         +-+-+-+-+-+-+-+-+

        where:

        P-flag:
+-+-+-+-+-+-+-+-+]]></artwork>

         </li>
       </ul>

       <ul empty="true" spacing="compact">
          <li>where:
          </li>
       </ul>

       <ul empty="true" spacing="compact">
          <li>
<dl spacing="compact" indent="9" ><dt>P-Flag:</dt><dd> When set to 1 1, one of the sub-TLVs
described in Section 2.1 <xref target="L3-adj" format="default"/> immediately follows the flags field.  If the P-flag P-Flag
is set to 0, then none of the sub-TLVs described in Section 2.1 <xref target="L3-adj" format="default"/> are present.

        Other bits: MUST
present.</dd>
</dl>
          </li>
       </ul>

       <ul empty="true">
          <li>
<dl indent="9">
<dt>Other bits:</dt><dd><bcp14>MUST</bcp14> be zero when originated and ignored when
         received.

   One received.</dd>
</dl>
          </li>
       </ul>

   </li></ul>

   </li>
</ul>

<ul empty="true" spacing="compact">
   <li>One or more of the following: L2 Bundle Attribute Descriptors
      Length (as defined below).
   </li>
</ul>

<ul empty="true" spacing="normal">
   <li>

<ul empty="true" spacing="normal">

         <li>Length of L2 Bundle Attribute Descriptor (1 octet)
        NOTE:
         </li>
         <li>
             <ul empty="true" spacing="normal">
               <li>NOTE: This includes all fields described below.

      Number
               </li>
            </ul>
         </li>
      </ul>
   </li>

   <li>
      <ul empty="true" spacing="normal">
         <li>Number of L2 Bundle Member Descriptors (1 octet)
         </li>
      </ul>
   </li>

   <li>
      <ul empty="true" spacing="normal">
         <li>
             L2 Bundle Member Link Local Identifiers Identifiers&br; (4 * Number of L2
             Bundle Member Descriptors octets)

        NOTE:
         </li>
      </ul>
   </li>

   <li>
      <ul empty="true" spacing="normal">
        <li>
           <ul empty="true" spacing="compact">
              <li>NOTE: An L2 Bundle Member Descriptor is a Link Local
              Identifier as defined in [RFC4202].

      sub-TLV(s)

      A <xref target="RFC4202"/>.
              </li>
           </ul>
        </li>
      </ul>
   </li>

   <li>
      <ul empty="true" spacing="normal">
         <li>
Sub-TLV(s)&br;A sub-TLV may define an attribute common to all of the bundle
members listed listed, or a sub-TLV it may define an attribute unique to each bundle member.
Use of these two classes of sub-TLVs is described in the following sections.

]]></artwork>
        </figure>NOTE:

         </li>
      </ul>
    </li>

</ul>

<ul empty="true">
   <li>
       <t>NOTE: Only one Parent L3 Neighbor Descriptor is present in a given
       TLV. Multiple L2 Bundle Attribute Descriptors may be present in a single
       TLV.</t>
     </li>
</ul>

<section title="Parallel anchor="L3-adj">
      <name>Parallel L3 Adjacencies"> Adjacencies</name>
        <t>When there exist multiple L3 adjacencies to the same neighbor neighbor,
        additional information is required to uniquely identify the L3
        Neighbor. One and only one of the following three sub-TLVs is used to
        uniquely identify the L3 adjacency:</t>

        <t><list style="symbols">
            <t>IPv4

        <ul>
            <li>IPv4 Interface Address (sub-TLV 6 defined in [RFC5305])</t>

            <t>IPv6 <xref target="RFC5305"/>)</li>

            <li>IPv6 Interface Address (sub-TLV 12 defined in [RFC6119])</t>

            <t>Link <xref target="RFC6119"/>)</li>

            <li>Link Local/Remote Identifiers (sub-TLV 4 defined in
            [RFC5307])</t>
          </list></t>
            <xref target="RFC5307"/>)</li>
	</ul>

        <t>When the P-bit P-Flag is set in the flags field in the Parent L3 Neighbor
        Descriptor
        Descriptor, one and only one of the above sub-TLVs MUST <bcp14>MUST</bcp14> be present. The
        chosen sub-TLV MUST <bcp14>MUST</bcp14> immediately follow the flags field described in
        Section 2.</t>
        <xref target="BUNDLE" />.</t>

        <t>These sub-TLVs MAY <bcp14>MAY</bcp14> be omitted if no parallel adjacencies to the
        neighbor exist.</t>
      </section>

      <section title="Shared

      <section>
      <name>Shared Attribute sub-TLVs"> Sub-TLVs</name>
        <t>These sub-TLVs advertise a single copy of an attribute (e.g. (e.g., link
        bandwidth). The attribute applies to all of the L2 Bundle Members in
        the set advertised under the preceding &nbsp;L2 preceding&nbsp;L2 Bundle Member
        Attribute Descriptor. No more than one copy of a given sub-TLV in this
        category may appear in the set of sub-TLVs under the preceding L2
        Bundle Member Attribute Descriptor. If multiple copies of a given
        sub-TLV are present present, all copies MUST <bcp14>MUST</bcp14> be ignored.</t>

        <t>The set of L2 Bundle Member Descriptors which that may be advertised
        under a single L2 Bundle Member Attribute Descriptor is therefore
        limited to bundle members which that share the set of attributes advertised
        in the shared attribute sub-TLVs.</t>

        <t>All existing sub-TLVs defined in the IANA registry for Sub-TLVs for TLVs 22, 23,
        141, 222, and 223 registry are in the category of shared attribute
        sub-TLVs unless otherwise specified in this document.</t>
      </section>
    </section>

    <section title="Advertising

    <section>
    <name>Advertising L2 Bundle Member Adj-SIDs">
      <t>[SR-ISIS] Adj-SIDs</name>
      <t><xref target="RFC8667"/> defines sub-TLVs to advertise Adj-SIDs for L3 adjacencies.
      However
      However, these sub-TLVs only support a the advertisement of a single Adj-SID.
      As it is expected that each L2 Bundle member Member will have unique Adj-SIDs
      in many deployments deployments, it is desirable to define a new sub-TLV which that allows
      more efficient encoding of a set of Adj-SIDs in a single sub-TLV. Two
      new sub-TLVs are therefore introduced to support advertising Adj-SIDs
      for L2 Bundle members. Members. The format of the new sub-TLVs is similar to that
      used for L3 adjacencies, but it is optimized to allow advertisement of a
      set of Adj-SIDs (one per L2 Bundle Member) in a single sub-TLV.</t>

      <t>The two new sub-TLVs defined in the following sections do not fall
      into the category of shared attribute sub-TLVs.</t>

      <section title="L2

      <section>
      <name>L2 Bundle Member Adjacency Segment Identifier sub-TLV"> Sub-TLV</name>
        <t>This sub-TLV is used to advertise Adj-SIDs for L2 Bundle Members
        associated with a parent L3 adjacency which that is Point-to-Point. point-to-point. The
        following format is defined for this sub-TLV:</t>

        <t><figure>
            <artwork><![CDATA[     Type: 41 (suggested value to be assigned by IANA)

<ul empty="true">
<li>
<dl>
<dt>Type:</dt>
<dd>41 (1 octet)
     Length: variable octet)</dd>
<dt>Length:</dt>
<dd>variable (1 octet)

     Flags: 1 octet octet)</dd>
<dt>Flags:</dt>
<dd>1-octet field of the following flags: flags:</dd>
</dl>

<ul empty="true"><li>
  <artwork name="" type="" align="left" alt=""><![CDATA[ 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|F|*|V|L|S|P|   |
         +-+-+-+-+-+-+-+-+

        where:

         NOTE: The flags are deliberately kept congruent to the flags
         in the L3 ADJ-SID defined in [SR-ISIS].
         * indicates a flag used in the L3 Adj-SID sub-TLV but which is
         NOT used in this sub-TLV. These bits SHOULD be sent as 0 and
         MUST be ignored on receipt.

         F-Flag: Address-Family flag.
+-+-+-+-+-+-+-+-+]]></artwork>
</li>

<li><t>where:</t>
<dl indent="9">
<dt>F-Flag:</dt><dd>Address-Family Flag.  If unset, then the Adj-SID refers to
an L2 Bundle Member with outgoing IPv4 encapsulation.  If set set, then the
Adj-SID refers to an L2 Bundle Member with outgoing IPv6 encapsulation.

         V-Flag: Value flag. encapsulation.</dd>
<dt>V-Flag:</dt><dd>Value Flag.  If set, then the Adj-SID carries a value.  By default
default, the flag is SET.

         L-Flag: Local SET.</dd>
<dt>L-Flag:</dt><dd>Local Flag.  If set, then the value/index carried by the
Adj-SID has local significance.  By default default, the flag is
         SET.

         S-Flag.  Set SET.</dd>
<dt>S-Flag:</dt><dd>Set Flag.  When set, the S-Flag indicates that the Adj-SID
refers to a set of L2 Bundle Members (and therefore
         MAY <bcp14>MAY</bcp14> be assigned to other
L2 Bundle Members as well).

         P-Flag.  Persistent flag. well).</dd>
<dt>P-Flag:</dt><dd>Persistent Flag.  When set, the P-Flag indicates that the
Adj-SID is persistently allocated, i.e., the Adj-SID value remains consistent
across router restart and/or interface flap.

         Other bits: MUST flap.</dd>
<dt>Other bits:</dt><dd><bcp14>MUST</bcp14> be zero when originated and ignored when
         received.

    Weight: 1
received.</dd>
</dl>
</li>

<li>
<t>NOTE: The flags are deliberately kept congruent to the flags in
the L3 ADJ-SID defined in <xref target="RFC8667"></xref>.  * indicates a flag used in the L3
Adj-SID sub-TLV, but one that is NOT used in this sub-TLV.  These bits <bcp14>SHOULD</bcp14>
be sent as 0 and <bcp14>MUST</bcp14> be ignored on receipt.</t>
</li>

</ul>
</li>

<li>
<dl indent="9">
<dt>Weight:
</dt>
<dd>1 octet.  The value represents the weight of the Adj-SID for the purpose
of load balancing.  The use of the weight is defined in [SR-ARCH]. <xref target="RFC8402"></xref>.
</dd>
</dl>
</li>

<li>
NOTE: Flags and weight are shared by all L2 Bundle Members listed in the L2
Bundle Attribute Descriptor.

    L2
</li>

<li>
<dl newline="true" indent="3">
<dt>L2 Bundle Member Adj-SID Descriptors. There MUST Descriptors:</dt>
<dd>There <bcp14>MUST</bcp14> be one descriptor for each of the L2 Bundle Members advertised
under the preceding L2 Bundle Member Attribute Descriptor.  Each descriptor
consists of one of the following fields:

      SID/Index/Label: according fields:</dd>
</dl>
</li>

<li>
<ul empty="true">
<li>
<dl indent="0">
<dt>SID/Index/Label:</dt>
<dd>According to the V V- and L flags, L-Flags, it contains
        either:

        *  A 3 octet either:</dd>
</dl>
</li>
<li>
<ul>
<li>A 3-octet local label where the 20 rightmost bits are used for encoding
the label value.  In this case case, the V V- and L
           flags MUST L-Flags <bcp14>MUST</bcp14> be set.

        *
</li>
<li> A 4 octet 4-octet index defining the offset in the SID/Label space advertised by
this router. See [SR-ISIS]. <xref target="RFC8667"/>. In this case V case, V- and L flags MUST L-Flags <bcp14>MUST</bcp14> be unset.

]]></artwork>
          </figure></t>
</li>
</ul>
</li>
</ul>
</li>

</ul>

   </section>

      <section title="L2

      <section>
      <name>L2 Bundle Member LAN Adjacency Segment Identifier sub-TLV"> SID Sub-TLV</name>
        <t>This sub-TLV is used to advertise Adj-SIDs for L2 Bundle Members
        associated with a parent L3 adjacency which that is a LAN adjacency. In LAN
        subnetworks, the Designated Intermediate System (DIS) is elected and
        originates the Pseudonode-LSP (PN-LSP) including all neighbors of the
        DIS. When Segment Routing is used, each router in the LAN MAY <bcp14>MAY</bcp14>
        advertise the Adj-SID of each of its neighbors on the LAN. Similarly,
        for each L2 Bundle Member Member, a router MAY <bcp14>MAY</bcp14> advertise an Adj-SID to each
        neighbor on the LAN.</t>

        <t>The following format is defined for this sub-TLV:</t>

        <t><figure>
            <artwork><![CDATA[     Type: 42 (suggested value to be assigned by IANA)

<ul empty="true">
<li>
<dl indent="0">
<dt>Type:</dt>
<dd>42 (1 octet)
     Length: variable octet)</dd>
<dt>Length:</dt>
<dd>variable (1 octet)
     Neighbor octet)</dd>
<dt>Neighbor System ID: 6 octets

     Flags: 1 octet ID:</dt>
<dd>6 octets</dd>
<dt>Flags:</dt>
<dd>1-octet field of the following flags: flags:</dd>
</dl>
<ul empty="true"><li>
  <artwork name="" type="" align="left" alt=""><![CDATA[ 0 1 2 3 4 5 6 7
+-+-+-+-+-+-+-+-+
|F|*|V|L|S|P|   |
         +-+-+-+-+-+-+-+-+

        where:

         NOTE: The flags are deliberately kept congruent to the flags
         in the L3 LAN_ADJ-SID defined in [SR-ISIS].
         * indicates a flag used in the L3 Adj-SID sub-TLV but which is
         NOT used in this sub-TLV. These bits SHOULD be sent as 0 and
         MUST be ignored on receipt.

         F-Flag: Address-Family flag.
+-+-+-+-+-+-+-+-+]]></artwork>
</li>

<li><t>where:</t>
<dl indent="9">
<dt>F-Flag:</dt><dd>Address-Family Flag.  If unset, then the Adj-SID refers to
an L2 Bundle Member with outgoing IPv4 encapsulation.  If set set, then the
Adj-SID refers to an L2 Bundle Member with outgoing IPv6 encapsulation.

         V-Flag: Value flag. encapsulation.</dd>
<dt>V-Flag:</dt>
<dd>Value Flag.  If set, then the Adj-SID carries a value.  By default default, the
flag is SET.

         L-Flag: Local SET.</dd>
<dt>L-Flag:</dt>
<dd>Local Flag.  If set, then the value/index carried by the Adj-SID has local
significance.  By default default, the flag is
         SET.

         S-Flag.  Set SET.</dd>

<dt>S-Flag:</dt>
<dd>Set Flag.  When set, the S-Flag indicates that the Adj-SID refers to a set
of L2 Bundle Members (and therefore
         MAY <bcp14>MAY</bcp14> be assigned to other L2 Bundle Members
as well).

         P-Flag.  Persistent flag. well).</dd>

<dt>P-Flag:</dt>
<dd>Persistent Flag.  When set, the P-Flag indicates that the Adj-SID is
persistently allocated, i.e., the Adj-SID value remains consistent across
router restart and/or interface flap.

         Other bits: MUST flap.</dd>
<dt>Other bits:</dt><dd><bcp14>MUST</bcp14> be zero when originated and ignored when
         received.

    Weight: 1
received.</dd>
</dl>
</li>

<li><t>NOTE: The flags are deliberately kept congruent to the flags in the L3
LAN Adjacency SID defined in <xref target="RFC8667"/>.  * indicates a flag used in the L3 Adj-SID
sub-TLV, but one that is NOT used in this sub-TLV.  These bits <bcp14>SHOULD</bcp14> be sent
as 0 and <bcp14>MUST</bcp14> be ignored on receipt.</t>
</li>

</ul>
</li>

<li>
<dl indent="9">
<dt>Weight:</dt>
<dd>1 octet.  The value represents the weight of the Adj-SID for the purpose
of load balancing.  The use of the weight is defined in [SR-ARCH].
<xref target="RFC8402"></xref>.</dd>
</dl>
</li>

<li>
NOTE: Flags and weight are shared by all L2 Bundle Members listed in the L2
Bundle Attribute Descriptor.

    L2
</li>

<li>
<dl newline="true" indent="3">
<dt>L2 Bundle Member LAN Adj-SID Descriptors. There MUST Adjacency SID Descriptors:</dt>
<dd>There <bcp14>MUST</bcp14> be one descriptor for each of the L2 Bundle Members advertised
under the preceding L2 Bundle Member Attribute Descriptor.  Each descriptor
consists of one of the following fields:

      SID/Index/Label: according fields:</dd>
</dl>
</li>

<li>
<ul empty="true">
<li>
<dl indent="0">
<dt>SID/Index/Label:</dt>
<dd>According to the V V- and L flags, L-Flags, it contains
        either:

        *  A 3 octet either:</dd>
</dl>
</li>
<li>
<ul>
<li>A 3-octet local label where the 20 rightmost bits are used for encoding
the label value.  In this case case, the V V- and L
           flags MUST L-Flags <bcp14>MUST</bcp14> be set.

        * set.</li>
<li> A 4 octet 4-octet index defining the offset in the SID/Label space advertised by
this router. See [SR-ISIS]. <xref target="RFC8667"/>. In this case V case, V- and L flags MUST L-Flags
<bcp14>MUST</bcp14> be unset.

]]></artwork>
          </figure></t> </li>
</ul>
</li>
</ul>
</li>

</ul>

 </section>

    </section>

    <section anchor="IANA" title="IANA Considerations"> anchor="IANA">
    <name>IANA Considerations</name>
      <t>This document adds the following new TLV to the IS-IS TLV "TLV Codepoints
      registry.</t>

      <t>Value: 25 (suggested - to be assigned by IANA)</t>

      <t>Name: L2
      Registry".</t>

<dl>
<dt>Value:</dt><dd>25</dd>
<dt>Name:</dt><dd>L2 Bundle Member Attributes</t> Attributes</dd>
</dl>
      <t>The name of the IANA registry for Sub-TLVs for TLVs 22, 23, 141, 222, and 223 registry
      needs to be
      has been changed to Sub-TLVs for TLVs 22, 23, 25, 141, 222, and 223
      registry. include sub-TLV 25. An additional column needs to be has been added to the registry to
      indicate which sub-TLVs may appear in the new L2 Bundle Member
      Attributes TLV. The column for TLV 25 has one of the following three
      values:</t>

      <t><figure>
          <artwork><![CDATA[y - sub-TLV

<dl indent="6">
<dt>y</dt><dd>sub-TLV may appear in TLV 25 but MUST NOT <bcp14>MUST
NOT</bcp14> be shared by multiple L2 Bundle Members
y(s) - sub-TLV Members</dd>
<dt>y(s)</dt><dd>sub-TLV may appear in TLV 25 and MAY <bcp14>MAY</bcp14>
be shared by multiple L2 Bundle Members
n - sub-TLV MUST NOT Members</dd>
<dt>n</dt><dd>sub-TLV <bcp14>MUST NOT</bcp14> appear in TLV 25]]></artwork>
        </figure></t> 25</dd>
</dl>

      <t>The following table indicates the appropriate settings for all
      currently defined sub-TLVs as regards with regard to their use in the new L2 Bundle
      Member Attributes TLV.</t>

      <t><figure>
          <artwork><![CDATA[    3 Administrative

<table anchor="table1">
<thead>
    <tr>
      <th align='left'>Value</th>
      <th align='left'>Description</th>
      <th align='left'>TLV 25</th>
    </tr>
</thead>
  <tbody>
    <tr>
      <td align="left">3</td>
      <td align="left">Administrative group (color) y(s)
    4 Link (color)</td>
      <td align="left">y(s)</td>
    </tr>

<tr>
<td align="left">4</td>
<td align="left">Link Local/Remote Identifiers y(s)
    6 IPv4 Identifiers</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">6</td>
<td align="left">IPv4 interface address y(s)
    8 IPv4 address</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">8</td>
<td align="left">IPv4 neighbor address y(s)
    9 Maximum address</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">9</td>
<td align="left">Maximum link bandwidth y(s)
    10 Maximum bandwidth</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">10</td>
<td align="left">Maximum reservable link bandwidth y(s)
    11 Unreserved bandwidth y(s)
    12 IPv6 bandwidth</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">11</td>
<td align="left">Unreserved bandwidth</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">12</td>
<td align="left">IPv6 Interface Address y(s)
    13 IPv6 Address</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">13</td>
<td align="left">IPv6 Neighbor Address y(s)
    14 Extended Address</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">14</td>
<td align="left">Extended Administrative Group y(s)
    18 TE Group</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">18</td>
<td align="left">TE Default metric y(s)
    19 Link-attributes y(s)
    20 Link metric</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">19</td>
<td align="left">Link-attributes</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">20</td>
<td align="left">Link Protection Type y(s)
    21 Interface Type</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">21</td>
<td align="left">Interface Switching Capability Descriptor y(s)
    22 Bandwidth Constraints y(s)
    23 Unconstrained Descriptor</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">22</td>
<td align="left">Bandwidth Constraints</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">23</td>
<td align="left">Unconstrained TE LSP Count y(s)
    24 Remote (sub-)TLV</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">24</td>
<td align="left">remote AS number n
    25 IPv4 number</td>
<td align="left">n</td>
</tr>

<tr>
<td align="left">25</td>
<td align="left">IPv4 remote ASBR Identifier n
    26 IPv6 Identifier</td>
<td align="left">n</td>
</tr>

<tr>
<td align="left">26</td>
<td align="left">IPv6 remote ASBR Identifier n
    27 Interface Identifier</td>
<td align="left">n</td>
</tr>

<tr>
<td align="left">27</td>
<td align="left">Interface Adjustment Capability Descriptor (IACD) y(s)
    28 MTU n
    29 SPB-Metric y(s)
    30 SPB-A-OALG y(s)
    33 Unidirectional (IACD)</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">28</td>
<td align="left">MTU</td>
<td align="left">n</td>
</tr>

<tr>
<td align="left">29</td>
<td align="left">SPB-Metric</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">30</td>
<td align="left">SPB-A-OALG</td>
<td align="left">y(s)</td>
</tr>

<tr>
<td align="left">33</td>
<td align="left">Unidirectional Link Delay y
    34 Min/Max Delay</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">34</td>
<td align="left">Min/Max Unidirectional Link Delay</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">35</td>
<td align="left">Unidirectional Delay y
    35 Unidirectional Delay Variation y
    36 Unidirectional Variation</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">36</td>
<td align="left">Unidirectional Link Loss y
    37 Unidirectional Loss</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">37</td>
<td align="left">Unidirectional Residual Bandwidth y
    38 Unidirectional Bandwidth</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">38</td>
<td align="left">Unidirectional Available Bandwidth y
    39 Unidirectional Bandwidth</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">39</td>
<td align="left">Unidirectional Utilized Bandwidth y
    40 RTM Capability n

]]></artwork>
        </figure></t> Bandwidth</td>
<td align="left">y</td>
</tr>

<tr>
<td align="left">40</td>
<td align="left">RTM Capability</td>
<td align="left">n</td>
</tr>
  </tbody>
</table>

      <t>This document adds the following new sub-TLVs to the sub-TLVs for
      TLVs 22, 23, 25, 141, 222, and 223 above registry.</t>

      <t>Value: 41 (suggested - to be assigned by IANA)</t>

      <t>Name: L2 Bundle Member Adj-SID</t>

      <t>This sub-TLV is allowed in the following TLVs:</t>

      <t><figure>
          <artwork><![CDATA[ 22 23 25 141 222 223
 n  n  y   n   n   n
]]></artwork>
        </figure></t>

      <t>Value: 42 (suggested to be assigned by IANA)</t>

      <t>Name: L2

<table anchor="iana-table" align="center">
  <thead>
    <tr>
      <th align='center'>Type</th>
      <th align='left'>Description</th>
      <th align='center'>22</th>
      <th align='center'>23</th>
      <th align='center'>25</th>
      <th align='center'>141</th>
      <th align='center'>222</th>
      <th align='center'>223</th>
    </tr>
  </thead>

  <tbody>
    <tr>
      <td align='center'>41</td>
      <td align='left'>L2 Bundle Member Adj-SID</td>
      <td align="center">n</td>
      <td align="center">n</td>
      <td align="center">y</td>
      <td align="center">n</td>
      <td align="center">n</td>
      <td align="center">n</td>
    </tr>

    <tr>
      <td align='center'>42</td>
      <td align='left'>L2 Bundle Member LAN Adj-SID</t>

      <t>This sub-TLV is allowed in the following TLVs:</t>

      <t><figure>
          <artwork><![CDATA[ 22 23 25 141 222 223
 n  n  y   n   n   n
]]></artwork>
        </figure></t> Adj-SID</td>
      <td align="center">n</td>
      <td align="center">n</td>
      <td align="center">y</td>
      <td align="center">n</td>
      <td align="center">n</td>
      <td align="center">n</td>
    </tr>
  </tbody>
</table>

    </section>

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

    <section>
    <name>Security Considerations</name>
      <t>The IS-IS protocol has supported the advertisement of link attribute
      information, including link identifiers, for many years. The
      advertisements defined in this document are identical to existing
      advertisements defined in [RFC4202], [RFC5305], [RFC7810], <xref target="RFC4202"/>, <xref
      target="RFC5305"/>, <xref target="RFC8570"/>, and [SR-ISIS]
      - <xref
      target="RFC8667"/>, but are associated with L2 links which that are part of a bundle interface
      on which the IS-IS protocol operates. There are therefore no new
      security issues introduced by the extensions in this document.</t>

      <t>As always, if the protocol is used in an environment where
      unauthorized access to the physical links on which IS-IS PDUs Protocol Data
      Units (PDUs) are sent
      occurs occurs, then attacks are possible. The use of
      authentication as defined in [RFC5304] <xref target="RFC5304"/> and [RFC5310] <xref
      target="RFC5310"/> is recommended to prevent such attacks.</t>
    </section>

    <section title="Contributors">
      <t>The following people gave a substantial contribution to the content
      of this document and should be considered as co-authors:</t>

      <t><figure>
          <artwork><![CDATA[Stefano Previdi
Cisco Systems
Via Del Serafico 200
Rome  0144
Italy

Email: sprevidi@cisco.com]]></artwork>
        </figure></t>
    </section>

    <section anchor="Acknowledgements" title="Acknowledgements">
      <t>The authors would like to thank Jon Mitchell for his careful
      review.</t>
    </section>

  </middle>

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

      <reference anchor="ISO10589">
        <front>
          <title>Intermediate system
          <title>Information technology -- Telecommunications and information
	  exchange between systems -- Intermediate System to Intermediate system
	  System intra-domain routeing information exchange protocol for use
	  in conjunction with the protocol for providing the
	  connectionless-mode Network Service network service (ISO 8473)</title>
          <author>
            <organization abbrev="ISO">International Organization for
            Standardization</organization>
          </author>
          <date month="Nov" month="November" year="2002"/>
        </front>
        <seriesInfo name="ISO/IEC" value="10589:2002, Second Edition"/>
      </reference>

      <reference anchor="IEEE802.1AX"> anchor="IEEE802.1AX" target="https://ieeexplore.ieee.org/document/7055197">
        <front>
          <title>IEEE Standard for Local and Metropolitan Area Networks - metropolitan area networks -- Link
          Aggregation.</title>
          Aggregation</title>
          <author>
            <organization abbrev="IEEE">Institute of Electrical and
            Electronics Engineers</organization> abbrev="IEEE">IEEE</organization>
          </author>

          <date month="Nov" year="2008"/>
        </front>
        <seriesInfo name="IEEE" value="802.1AX"/>
      </reference>

<!-- draft-ietf-isis-segment-routing-extensions-25: Companion document -->
<reference anchor="SR-ISIS">  anchor='RFC8667' target='https://www.rfc-editor.org/info/rfc8667'>
<front>
<title>IS-IS Extensions for Segment Routing,
          draft-ietf-isis-segment-routing-extensions-12(work in
          progress)</title> Routing</title>
<author initials='S' surname='Previdi' fullname='Stefano Previdi' role='editor'><organization/></author>
<author initials='L' surname='Ginsburg' fullname='Les Ginsburg' role='editor'><organization /></author>
<author initials='C' surname='Filsfils' fullname='Clarence Filsfils'><organization /></author>
<author initials='A' surname='Bashandy' fullname='Ahmed Bashandy'><organization /></author>
<author initials='H' surname='Gredler' fullname='Hannes Gredler'><organization /></author>
<author fullname="Previdi S., et al,"/> initials='B' surname='Decraene' fullname='Bruno Decraene'><organization /></author>
<date month="April" year="2017"/> year='2019' month='December'/>
</front>
<seriesInfo name='RFC' value='8667'/>
<seriesInfo name='DOI' value='10.17487/RFC8667'/>
</reference>

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

      <?rfc include='reference.RFC.4202'?>

      <?rfc include='reference.RFC.5304'?>

      <?rfc include='reference.RFC.5305'?>

      <?rfc include='reference.RFC.5307'?>

      <?rfc include='reference.RFC.5310'?>

      <?rfc include='reference.RFC.6119'?>

      <?rfc include='reference.RFC.7810'?>

<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.2119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8174.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.4202.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5304.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5305.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5307.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.5310.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.6119.xml"/>
<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8570.xml"/>
    </references>

    <references title="Informational References">
      <?rfc include='reference.RFC.4655'?>

<references>
  <name>Informative References</name>

<reference anchor="SR-ARCH">  anchor='RFC4655' target='https://www.rfc-editor.org/info/rfc4655'>
<front>
          <title>Segment Routing Architecture,
          draft-ietf-spring-segment-routing-11(work in progress)</title>
<title>A Path Computation Element (PCE)-Based Architecture</title>
<author initials='A.' surname='Farrel' fullname='A. Farrel'><organization /></author>
<author initials='JP.' surname='Vasseur' fullname='JP. Vasseur'><organization /></author>
<author fullname="Filsfils C., et al,"/> initials='J.' surname='Ash' fullname='J. Ash'><organization /></author>
<date month="February" year="2017"/> year='2006' month='August' />
</front>
<seriesInfo name='RFC' value='4655'/>
<seriesInfo name='DOI' value='10.17487/RFC4655'/>
</reference>

<xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8402.xml"/>
</references>

    <section title="Example Encoding">
      <t/>
</references>

<section>
<name>Example Encoding</name>

      <t>Below is an example encoding of L2 Bundle advertisements in a case
      where we have two parallel adjacencies to the same neighbor whose
      system-id is 1234.1234.1234.00. The two L2 bundles have the following
      sets of attributes:</t>

      <t><figure>
          <artwork><![CDATA[L3

<t>L3 Adjacency #1
L3 #1</t>
<t>L3 IPv4 local link address: 192.0.2.1
Four 192.0.2.1</t>
<t>Four bundle members with the following attributes:

--------------------------------------------------
Num | Link attributes:</t>

<table anchor="Adj1">
<thead>
<tr>
<th align='center'>Num</th>
<th align='center'>Link Local ID | Bandwidth | Adj-SID/Weight |
--------------------------------------------------
1   | 0x11111111    | 1G        | 0x11111/1      |
--------------------------------------------------
2   | 0x11112222    | 1G        | 0x11112/1      |
--------------------------------------------------
3   | 0x11113333    | 10G       | 0x11113/1      |
--------------------------------------------------
4   | 0x11114444    | 10G       | 0x11114/1      |
--------------------------------------------------

L3 ID</th>
<th align='center'>Bandwidth</th>
<th align='center'>Adj-SID/Weight</th>
</tr>
</thead>

<tbody>
<tr>
<td align="center">1</td>
<td align="center">0x11111111</td>
<td align="center">1G</td>
<td align="center">0x11111/1 </td>
</tr>

<tr>
<td align="center">2</td>
<td align="center">0x11112222</td>
<td align="center">1G</td>
<td align="center">0x11112/1</td>
</tr>

<tr>
<td align="center">3</td>
<td align="center">0x11113333</td>
<td align="center">10G</td>
<td align="center">0x11113/1</td>
</tr>

<tr>
<td align="center">4</td>
<td align="center">0x11114444</td>
<td align="center">10G</td>
<td align="center">0x11114/1</td>
</tr>

</tbody>
</table>

<t>L3 Adjacency #2
L3 #2</t>
<t>L3 IPv4 local link address: 192.0.2.2
Three 192.0.2.2</t>
<t>Three bundle members with the following attributes:

--------------------------------------------------
Num | Link attributes:</t>

<table anchor="adj2">
  <thead>
    <tr>
      <th align='center'>Num</th>
      <th align='center'>Link Local ID | Bandwidth | Adj-SID/Weight |
--------------------------------------------------
1   | 0x22221111    | 10G       | 22221/1        |
--------------------------------------------------
2   | 0x22222222    | 10G       | 22222/1        |
--------------------------------------------------
3   | 0x22223333    | 10G       | 22223/1        |
--------------------------------------------------
]]></artwork>
        </figure>This ID</th>
      <th align='center'>Bandwidth</th>
      <th align='center'>Adj-SID/Weight</th>
    </tr>
  </thead>
  <tbody>
<tr>
<td align="center">1</td>
<td align="center">0x22221111</td>
<td align="center">10G</td>
<td align="center">22221/1</td>
</tr>

<tr>
<td align="center">2</td>
<td align="center">0x22222222</td>
<td align="center">10G</td>
<td align="center">22222/1</td>
</tr>

<tr>
<td align="center">3</td>
<td align="center">0x22223333</td>
<td align="center">10G</td>
<td align="center">22223/1</td>
</tr>
  </tbody>
</table>

<t>This requires two TLVs, one for each L3 adjacency.</t>

<t>TLV for Adjacency #1:</t>

      <t><figure>

<artwork><![CDATA[
 0                   1
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Type(25)     |Len: 64     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parent Length(64)    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>Parent L3 Neighbor Descriptor Descriptor</t>
<artwork><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor System-ID octets 1-4: 1234.1234                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| System-ID octets 5-6: 1234    | P-node: 00    |1|0|0|0|0|0|0|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>IPv4 Interface Address sub-TLV Sub-TLV</t>
<artwork><![CDATA[
 0                   1
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Type(6))  Type(6)      | Length(4)     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 address:192.0.2.1 address: 192.0.2.1                                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>L2 Bundle Attribute Descriptors Descriptors</t>
<artwork><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Len:9+6+10 = 25| # Desc: 2     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #1: 0x11111111            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #2: 0x11112222            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Maximum
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>Maximum Link Bandwidth sub-TLV Sub-TLV</t>
<artwork><![CDATA[
 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(9)       | Length(4)    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth Value: 1G/8                                         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>L2 Bundle Member Adjacency Segment Identifier sub-TLV Adj-SID Sub-TLV</t>
<artwork><![CDATA[
 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(41)     | Length(8)     |0|0|1|1|0|0|0|0| Weight: 1     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #1: 0x11111         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #2: 0x11112         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>L2 Bundle Attribute Descriptors Descriptors</t>
<artwork><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Len:9+6+10 = 25| # Desc: 2     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #3: 0x11113333            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #4: 0x11114444            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Maximum
]]></artwork>

<t>Maximum Link Bandwidth sub-TLV Sub-TLV</t>
<artwork><![CDATA[
 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(9)       | Length(4)    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth Value: 10G/8                                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>L2 Bundle Member Adjacency Segment Identifier sub-TLV Adj-SID Sub-TLV</t>
<artwork><![CDATA[
 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(41)     | Length(8)     |0|0|1|1|0|0|0|0| Weight: 1     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #3: 0x11113         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #4: 0x11114         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

]]></artwork>
        </figure></t>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>TLV for Adjacency #2</t>

      <t><figure> #2:</t>

<artwork><![CDATA[
 0                   1
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Type(25)     | Len: 46 Length(46)    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Parent
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>Parent L3 Neighbor Descriptor Descriptor</t>
<artwork><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Neighbor System-ID octets 1-4: 1234.1234                      |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| System-ID octets 5-6: 1234    | P-node: 00    |1|0|0|0|0|0|0|0|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

IPv4
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>IPv4 Interface Address sub-TLV Sub-TLV</t>
<artwork><![CDATA[
 0                   1
 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|  Type(6))  Type(6)      | Length(4)     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| IPv4 address: 192.0.2.2                                       |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>L2 Bundle Attribute Descriptors Descriptors</t>
<artwork><![CDATA[
 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|Len:13+6+13=32 | # Desc: 3     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #1: 0x22221111            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #2: 0x22222222            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Link Local Identifier Bundle Member #3: 0x22223333            |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Maximum
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>Maximum Link Bandwidth sub-TLV Sub-TLV</t>
<artwork><![CDATA[
 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(9)       | Length(4)    |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Bandwidth Value: 10G/8                                        |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

L2
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>

<t>L2 Bundle Member Adjacency Segment Identifier sub-TLV Adj-SID Sub-TLV</t>
<artwork><![CDATA[
 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(41)     | Length(11)    |0|0|1|1|0|0|0|0| Weight: 1     |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #1: 0x22221         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #2: 0x22222         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Local Label Bundle Member #3: 0x22223         |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
]]></artwork>
        </figure></t>
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
    </section>

    <section numbered="false">
<name>Acknowledgements</name>
      <t>The authors would like to thank Jon Mitchell for his careful
      review.</t>
    </section>

<section numbered="false">
<name>Contributors</name>
      <t>The following people gave a substantial contribution to the content
      of this document and should be considered coauthors:</t>

          <artwork><![CDATA[Stefano Previdi
Huawei Technologies
Italy

Email: stefano@previdi.net]]></artwork>

    </section>

  </back>
</rfc>