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<rfc category="std" xmlns:xi="http://www.w3.org/2001/XInclude"
     docName="draft-ietf-dhc-slap-quadrant-12"
     ipr="trust200902"> number="8948" ipr="trust200902"
     obsoletes="" updates="" submissionType="IETF" category="std"
     consensus="true" xml:lang="en" tocInclude="true" tocDepth="3"
     symRefs="true" sortRefs="true" version="3">

  <!-- xml2rfc v2v3 conversion 3.2.1 -->
  <front>

    <title abbrev="DHCPv6 SLAP quadrant selection">
       SLAP quadrant selection option Quadrant Selection">
       Structured Local Address Plan (SLAP) Quadrant Selection Option for DHCPv6
    </title>

    <!-- AUTHORS -->
    <seriesInfo name="RFC" value="8948"/>
    <author fullname="Carlos J. Bernardos" initials="CJ." surname="Bernardos">
      <organization abbrev="UC3M">
        Universidad Carlos III de Madrid
      </organization>
      <address>
        <postal>
          <street>Av. Universidad, 30</street>
          <city>Leganes, Madrid</city>
          <code>28911</code>
          <country>Spain</country>
        </postal>
        <phone>+34 91624 6236</phone>
        <email>cjbc@it.uc3m.es</email>
        <uri>http://www.it.uc3m.es/cjbc/</uri>
      </address>
    </author>
    <author fullname="Alain Mourad" initials="A." surname="Mourad">
      <organization abbrev="InterDigital">
        InterDigital Europe
      </organization>
      <address>
        <email>Alain.Mourad@InterDigital.com</email>
        <uri>http://www.InterDigital.com/</uri>
      </address>
    </author>
    <date month="October" year="2020" /> month="November" year="2020"/>
    <area>Internet</area>
    <workgroup>DHC WG</workgroup>

    <abstract>
      <t>
The IEEE originally structured the 48-bit MAC Media Access Control (MAC) address space in such a way that half
of it was reserved for local use. In 2017, the IEEE published a new standard (IEEE
Std 802c) with a new optional "Structured Structured Local Address Plan" Plan (SLAP). It
specifies different assignment approaches in four specified regions of the local
MAC address space.
      </t>
      <t>
The IEEE is developing protocols to assign addresses (IEEE
P802.1CQ). There is work also work
in the IETF on specifying a new mechanism that extends DHCPv6 operation to
handle the local MAC address assignments.
      </t>
      <t>
This document proposes extensions to DHCPv6 protocols to enable a DHCPv6 client
or a DHCPv6 relay to indicate a preferred SLAP quadrant to the server, server so that
the server may allocate MAC addresses in the quadrant requested by the relay or
client. A new DHCPv6 option (QUAD) is defined for this purpose.
      </t>
    </abstract>
  </front>
  <middle>
    <section anchor="sec:introduction" title="Introduction">

      <t> anchor="sec_introduction" numbered="true" toc="default">
      <name>Introduction</name>
      <t>The IEEE structures the 48-bit MAC address space in such a way that half of it was is
reserved for local use (where the Universal/Local -- U/L -- (U/L) bit is set to 1). In
2017, the IEEE published a new standard (IEEE Std 802c <xref target="IEEEStd802c"/>)
which target="IEEEStd802c" format="default"/>
that defines a new optional "Structured Structured Local Address Plan" Plan (SLAP) that
specifies different assignment approaches in four specified regions of the local
MAC address space. These four regions, called SLAP quadrants, are briefly
described below (see <xref target="fig:ieee_48bit_mac" /> target="fig_ieee_48bit_mac" format="default"/> and <xref
target="fig:slap_quadrants" /> target="fig_slap_quadrants" format="default"/> for details):

        <list style="symbols">

          <t>

      </t>
      <ul spacing="normal">
        <li>
In SLAP Quadrant 01, “Extended Extended Local Identifier” Identifier (ELI) MAC addresses are
assigned based on a 24-bit Company ID (CID), which is assigned by the IEEE Registration
Authority (RA). The remaining bits are specified as an extension by the CID
assignee or by a protocol designated by the CID assignee.
          </t>

          <t>
          </li>
        <li>
In SLAP Quadrant 11, “Standard Standard Assigned Identifier” Identifier (SAI) MAC addresses are
assigned based on a protocol specified in an IEEE 802 standard. For 48-bit MAC
addresses, 44 bits are available. Multiple protocols for assigning SAIs may be
specified in IEEE standards. Coexistence of multiple protocols may be supported
by limiting the subspace available for assignment by each protocol.
          </t>

          <t>
          </li>
        <li>
In SLAP Quadrant 00, “Administratively Administratively Assigned Identifier” Identifier (AAI) MAC addresses
are assigned locally by an administrator. Multicast IPv6 packets use a
destination address starting in 33-33, so AAI addresses in that range should not
be assigned. For 48-bit MAC addresses, 44 bits are available.
          </t>

          <t>
          </li>
        <li>
SLAP Quadrant 10 is “Reserved "Reserved for future use” use" where MAC addresses may be
assigned using new methods yet to be defined, defined or until then by an administrator
as in the AAI quadrant. For 48-bit MAC addresses, 44 bits would be available.
          </t>

        </list>

      </t>
          </li>
      </ul>
      <figure anchor="fig:ieee_48bit_mac" title="IEEE 48-bit anchor="fig_ieee_48bit_mac">
        <name>IEEE 48-Bit MAC address structure Address Structure (in IEEE representation)" > Representation)</name>

        <artwork><![CDATA[
       LSB                MSB
       M  X  Y  Z  -  -  -  -
       |  |  |  |
       |  |  |  +------------ SLAP Z-bit
       |  |  +--------------- SLAP Y-bit
       |  +------------------ X-bit (U/L) = 1 for locally assigned
       +--------------------- M-bit (I/G) (unicast/group)

       Legend:
       LSB: Least Significant Bit
       MSB: Most Significant Bit
       ]]></artwork>

      </figure>

<figure anchor="fig:slap_quadrants" title="SLAP quadrants" >
<artwork><![CDATA[
+----------+-------+-------+-----------------------+----------------+
| Quadrant | Y-bit | Z-bit | Local Identifier Type | Local          |
|          |       |       |                       |

      <table anchor="fig_slap_quadrants">
        <name>SLAP Quadrants</name>
	<thead>
	  <tr>
	    <th>Quadrant</th>
	    <th>Y-bit</th>
	    <th>Z-bit</th>
	    <th>Local Identifier     |
+----------+-------+-------+-----------------------+----------------+
|    01    |   0   |   1   | Extended Local        | ELI            |
|    11    |   1   |   1   | Standard Assigned     | SAI            |
|    00    |   0   |   0   | Administratively      | AAI            |
|          |       |       | Assigned              |                |
|    10    |   1   |   0   | Reserved              | Reserved       |
+----------+-------+-------+-----------------------+----------------+
]]></artwork>
</figure> Type</th>
	    <th>Local Identifier</th>
	  </tr>
	</thead>
	<tbody>
	  <tr>
	    <td>01</td>
	    <td>0</td>
	    <td>1</td>
	    <td>Extended Local</td>
	    <td>ELI</td>
	  </tr>
	  <tr>
	    <td>11</td>
	    <td>1</td>
	    <td>1</td>
	    <td>Standard Assigned</td>
	    <td>SAI</td>
	  </tr>
	  <tr>
	    <td>00</td>
	    <td>0</td>
	    <td>0</td>
	    <td>Administratively Assigned</td>
	    <td>AAI</td>
	  </tr>
	  <tr>
	    <td>10</td>
	    <td>1</td>
	    <td>0</td>
	    <td>Reserved</td>
	    <td>Reserved</td>
	  </tr>
	</tbody>
</table>

      <section anchor="sec:ps" title="Problem statement"> anchor="sec_ps" numbered="true" toc="default">
        <name>Problem Statement</name>
        <t>

The IEEE is developing mechanisms to assign addresses (IEEE P802.1CQ project) <xref
target="IEEE-P802.1CQ-Project" />. There
is also ongoing work in the IETF format="default"/>. And <xref target="I-D.ietf-dhc-mac-assign" />
specifying target="RFC8947"
format="default"/> specifies a new mechanism that extends DHCPv6 operation to handle the local MAC
address assignments.

This document proposes extensions to DHCPv6 protocols to
enable a DHCPv6 client or a DHCPv6 relay to indicate a preferred SLAP quadrant
to the server, server so that the server may allocate the MAC addresses in the quadrant
requested by the relay or client.
        </t>
        <t>
In the following, we describe two application scenarios in which a need arises
to assign local MAC addresses according to preferred SLAP quadrants.
        </t>
        <section anchor="sec:wifi_devices" title="WiFi anchor="sec_wifi_devices" numbered="true" toc="default">
          <name>Wi-Fi (IEEE 802.11) devices"> Devices</name>
          <t>
Today, most WiFi Wi-Fi devices come with interfaces that have a “burned in” "burned-in" MAC
address, allocated from the universal address space using a 24-bit
Organizationally Unique Identifier (OUI, assigned (OUI) (assigned to IEEE 802 interface
vendors). However, recently, the need to assign local (instead of universal) MAC
addresses has emerged in particular particularly in the following two scenarios:

            <list style="symbols">

              <t>
          </t>
          <ul spacing="normal">
            <li>
IoT (Internet of Things): In general, composed of constrained devices <xref
target="RFC7228" /> format="default"/> with constraints such as available power
and energy, memory,
and processing resources. Examples of this include sensors and actuators for
health or home automation applications. Given the increasingly high number of
these devices, manufacturers might prefer to equip devices with temporary MAC
addresses used only at first boot. These temporary MAC addresses would just be
used to send initial DHCP packets to available DHCP servers. IoT devices
typically need a single MAC address for each available network interface. Once
the server assigns a MAC address, the device would abandon its temporary MAC
address. Home automation IoT devices typically do not move (however, note that
there is an increase of mobile smart health monitoring devices, which are mobile). devices). For
this type of device, in general, any type of SLAP quadrant would be good for
assigning addresses, but ELI/SAI quadrants might be more suitable in some
scenarios. For example, the device might need to use an address from the CID
assigned to the IoT communication device communication&nbsp;device vendor, thus preferring the ELI
quadrant.
              </t>

              <t>
              </li>
            <li>
Privacy: Today, MAC addresses allow the exposure of users’ user locations making it
relatively easy to track users’ user movements. One of the mechanisms considered to
mitigate this problem is the use of local random MAC addresses, addresses: changing them
every time the user connects to a different network. In this scenario, devices
are typically mobile. Here, AAI is probably the best SLAP quadrant from which to
assign addresses, as addresses; it is the best fit for randomization of addresses, and it is
not required for the addresses to survive when changing networks.
              </t>

            </list>

          </t>
              </li>
          </ul>
        </section>
        <section anchor="sec:hypervisors" title="Hypervisor: migratable vs non-migratable functions"> anchor="sec_hypervisors" numbered="true" toc="default">
          <name>Hypervisor: Functions That Are and Are Not Migratable</name>
          <t>
In large scale large-scale virtualization environments, thousands of virtual machines (VMs)
are active. These VMs are typically managed by a hypervisor, which is in charge of
spawning and stopping VMs as needed. The hypervisor is also typically in charge
of assigning new MAC addresses to the VMs. If a DHCP solution is in place for
that, the hypervisor acts as a DHCP client and requests that available DHCP servers
to
assign one or more MAC addresses (an address block). The hypervisor does not
use those addresses for itself, but rather it uses them to create new VMs with
appropriate MAC addresses. If we assume very large data center data-center environments,
such as the ones that are typically used nowadays, it is expected that the data
center is divided in different network regions, each one managing its own local
address space. In this scenario, there are two possible situations that need to
be tackled:

            <list style="symbols">

              <t>
Migratable functions.

          </t>
          <ul spacing="normal">
<li>Migratable functions: If a VM (providing a given function) needs to be migrated
to another region of the data center (e.g., for maintenance, resilience,
end-user mobility, etc.), the VM's networking context needs to migrate with the
VM. This includes the VM's MAC address(es). Since the assignments from the
ELI/SAP
ELI/SAI SLAP quadrants are governed by rules per IEEE Std 802c, they are more
appropriate for use to ensure MAC address uniqueness globally in the datacenter.
              </t>

              <t>
Non-migratable functions.  If data center.
              </li>

<li>Functions that are not migratable: If a VM will not be migrated to another region another region of the
data center, there are no requirements associated with its with its MAC address. In this
case, it is simpler to allocate it from the AAI SLAP quadrant, that which does
not need to be unique across multiple data centers (i.e., each region can
manage its own MAC address assignment, assignment without checking for duplicates
globally).
              </t>

            </list>

          </t>
              </li>
          </ul>
        </section>
      </section>
    </section>
    <section anchor="sec:terminology" title="Terminology"> anchor="sec_terminology" numbered="true" toc="default">
      <name>Terminology</name>
      <t>
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
"SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", "<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 "OPTIONAL" "<bcp14>OPTIONAL</bcp14>" in this
document are to be interpreted as described in BCP 14 <xref target="RFC2119" /> format="default"/>
        <xref target="RFC8174" /> format="default"/> when, and only when, they appear in all capitals, as
shown here.
      </t>
      <t>
Where relevant, the DHCPv6 terminology from the DHCPv6 Protocol <xref
target="RFC8415"/> target="RFC8415" format="default"/> also applies here. Additionally, the following definitions
are updated for this document.
      </t>

      <t>
        <list hangIndent="14" style="hanging">

          <t hangText="IA_LL">Identity Association for Link-Layer Address: an
          identity association (IA) used to request or assign

<dl newline="false" spacing="normal" indent="15">
          <dt>address</dt>
        <dd>Unless specified otherwise, a
          link-layer addresses. Section 10.1 of (or MAC) address, as specified in
          <xref target="I-D.ietf-dhc-mac-assign" /> provides details on
          the IA_LL option.</t>

          <t hangText="LLADDR">Link-layer target="IEEEStd802" format="default"/>. The address option that is used to request 6 or
          assign a block 8 bytes long.</dd>
        <dt>address block</dt>
        <dd>A number of consecutive link-layer
          addresses. Section 10.2 of
          <xref target="I-D.ietf-dhc-mac-assign" /> provides details on the LLADDR
          option.</t>

          <t hangText="client">A node that is interested An address block is expressed as a first address
          plus a number that designates the number of additional (extra) addresses.
          A single address can be represented by the address itself and zero
          extra addresses.</dd>
          <dt>client</dt>
        <dd>A node that is interested in obtaining link-layer
          addresses. It implements the basic DHCP mechanisms needed by a DHCP
          client
          client, as described in <xref target="RFC8415"/> target="RFC8415" format="default"/>, and supports the options
          (IA_LL and LLADDR) specified in <xref target="I-D.ietf-dhc-mac-assign" />, target="RFC8947" format="default"/>
          as well as the new option (QUAD) specified in this document. The client
          may or may not support IPv6 address assignment and prefix delegation delegation, as
          specified in <xref target="RFC8415"/>.</t>

          <t hangText="server">A node that manages link-layer address allocation and
          is able to respond target="RFC8415" format="default"/>.</dd>
        <dt>IA_LL</dt>
        <dd>Identity Association for Link-Layer Address, an
          identity association (IA) used to client queries. It implements basic DHCP
          server functionality as described in <xref target="RFC8415"/> and
          supports the options (IA_LL and LLADDR) specified in request or assign
          link-layer addresses.
          <xref target="I-D.ietf-dhc-mac-assign" />, as well as target="RFC8947" section="11.1" sectionFormat="of"/> provides details on
          the new IA_LL option.</dd>
        <dt>LLADDR</dt>
        <dd>Link-layer address option
          (QUAD) specified in this document. The server may that is used to request or may not support
          IPv6 address assignment and prefix delegation as specified in
          assign a block of link-layer addresses.
          <xref target="RFC8415"/>.</t>

          <t hangText="relay"> target="RFC8947" section="11.2" sectionFormat="of"/> provides details on the LLADDR
        option.</dd>
	        <dt>relay</dt>
        <dd> A node that acts as an intermediary to deliver
          DHCP messages between clients and servers. A relay, based on local
          knowledge and policies, may include the preferred SLAP quadrant in a QUAD
          option sent to the server. The relay implements basic DHCPv6 relay agent
          functionality
          functionality, as described in <xref target="RFC8415"/>.</t>

          <t hangText="address">Unless specified otherwise, an address means a target="RFC8415" format="default"/>.</dd>
        <dt>server</dt>
        <dd>A node that manages link-layer (or MAC) address, address allocation and
          is able to respond to client queries. It implements basic DHCP
          server functionality, as described in <xref target="RFC8415" format="default"/>, and
          supports the options (IA_LL and LLADDR) specified in IEEE Std 802
          <xref target="IEEEStd802" />. The address is six or eight bytes long.</t>

          <t hangText="address block">A number of consecutive link-layer
          addresses. An address block is expressed target="RFC8947" format="default"/> as well as a first address
          plus a number that designates the number of additional (extra) addresses.
          A single address can be represented by the new option
          (QUAD) specified in this document. The server may or may not support
          IPv6 address itself assignment and zero
          extra addresses.</t>
        </list>

      </t> prefix delegation, as specified in
          <xref target="RFC8415" format="default"/>.</dd>
      </dl>
    </section>
    <section anchor="sec:dhcpv6_extensions" title="DHCPv6 Extensions"> anchor="sec_dhcpv6_extensions" numbered="true" toc="default">
      <name>DHCPv6 Extensions</name>
      <section anchor="sec:dhcpv6_ext_client" title="Address anchor="sec_dhcpv6_ext_client" numbered="true" toc="default">
        <name>Address Assignment from the Preferred SLAP Quadrant Indicated by the Client"> Client</name>
        <t>
Next, we describe the protocol operations for a client to select a preferred
SLAP quadrant using the DHCPv6 signaling procedures described in <xref
target="I-D.ietf-dhc-mac-assign" />. target="RFC8947" format="default"/>. The signaling flow is shown in <xref
target="fig:dhcpv6_flow_client" />. target="fig_dhcpv6_flow_client" format="default"/>.
        </t>

        <figure anchor="fig:dhcpv6_flow_client" title="DHCPv6 signaling flow (client-server)" >
<artwork><![CDATA[ anchor="fig_dhcpv6_flow_client">
          <name>DHCPv6 Signaling Flow (Client-Server)</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
 +--------+                            +--------+
 | DHCPv6 |                            | DHCPv6 |
 | client |                            | server |
 +--------+                            +--------+
     |                                      |
     +----1. Solicit(IA_LL(LLADDR,QUAD))--->|
     |                                      |
     |<--2. Advertise(IA_LL(LLADDR,QUAD))---+
     |                                      |
     +---3. Request(IA_LL(LLADDR,QUAD))---->|
     |                                      |
     |<------4. Reply(IA_LL(LLADDR))--------+
     |                                      |
     ·                                      ·
     ·
     .                                      .
     .          (timer expiring)            ·
     ·                                      ·            .
     .                                      .
     |                                      |
     +---5. Renew(IA_LL(LLADDR,QUAD))------>|
     |                                      |
     |<-----6. Reply(IA_LL(LLADDR))---------+
     |                                      |
]]></artwork>
        </figure>

        <t>
          <list style="numbers">

            <t>
        <ol spacing="normal" type="1"><li>
Link-layer addresses (i.e., MAC addresses) are assigned in blocks. The smallest
block is a single address. To request an assignment, the client sends a Solicit
message with an IA_LL option in the message. The IA_LL option MUST <bcp14>MUST</bcp14> contain a an
LLADDR option. In order to indicate the preferred SLAP quadrant(s), the IA_LL
option includes the new OPTION_SLAP_QUAD option in the IA_LL-option field (alongside the
LLADDR option).
            </t>

            <t>
            </li>
            <li>

The server, upon receiving an IA_LL option in Solicit, a Solicit message, inspects its contents.
For each of the entries in the OPTION_SLAP_QUAD, in order of the preference field
(highest to lowest), the server checks if it has a configured MAC address pool
matching the requested quadrant identifier, identifier and an available range of addresses
of the requested size. If suitable addresses are found, the server sends back an
Advertise message with an IA_LL option containing an LLADDR option that
specifies the addresses being offered. If the server manages a block of
addresses belonging to a requested quadrant, the addresses being offered MUST <bcp14>MUST</bcp14>
belong to a requested quadrant. If the server does not have a configured address
pool matching the client's request, it SHOULD <bcp14>SHOULD</bcp14> return the IA_LL option with the
addresses being offered belonging to a quadrant managed by the server (following
a local policy to select from which of the available quadrants). If the server
has a configured address pool of the correct quadrant, quadrant but no available
addresses, it MUST <bcp14>MUST</bcp14> return the IA_LL option containing a Status Code option with
status set to NoAddrsAvail.
            </t>

            <t>
            </li>
          <li>
The client waits for available servers to send Advertise responses and picks one
server
server, as defined in Section 18.2.9 of <xref target="RFC8415" />. section="18.2.9" sectionFormat="of"/>. The client
SHOULD NOT
<bcp14>SHOULD NOT</bcp14> pick a server that does not advertise an address in the requested
quadrant(s). The client then sends a Request message that includes the IA_LL
container option with the LLADDR option copied from the Advertise message sent
by the chosen server. It includes the preferred SLAP quadrant(s) in a new QUAD
IA_LL-option.
            </t>

            <t>
IA_LL option.
            </li>
          <li>
Upon reception of a Request message with an IA_LL container option, the server
assigns requested addresses. The server MAY <bcp14>MAY</bcp14> alter the allocation at this time
(e.g., by reducing the address block). It then generates and sends a Reply
message back to the client. Upon receiving a Reply message, the client parses
the IA_LL container option and may start using all provided addresses. Note that
a client that has included a Rapid Commit option in the Solicit, Solicit
message may receive a
Reply message in response to the Solicit message and skip the
Advertise and Request message steps above
(following standard DHCPv6 procedures).
            </t>

            <t>
            </li>
          <li>
The client is expected to periodically renew the link-layer addresses addresses, as
governed by T1 and T2 timers. This mechanism can be administratively disabled by
the server sending "infinity" as the T1 and T2 values (see Section 7.7 of <xref target="RFC8415" />). section="7.7" sectionFormat="of"/>). The client sends a Renew option after T1. It includes the
preferred SLAP quadrant(s) in the new QUAD IA_LL-option, IA_LL option, so in case the server
is unable to extend the lifetime on the existing address(es), the preferred
quadrants are known for the allocation of any "new" (i.e., different) addresses.
            </t>

            <t>
            </li>
          <li>
The server responds with a Reply message, message with an IA_LL option that includes an
LLADDR option with extended lifetime.
            </t>

          </list>

        </t>
            </li>
        </ol>
        <t>
The client SHOULD <bcp14>SHOULD</bcp14> check if the received MAC address comes from one of the
requested quadrants. It MAY <bcp14>MAY</bcp14> repeat the process selecting a different DHCP server.
        </t>
      </section>
      <section anchor="sec:dhcpv6_ext_relay" title="Address anchor="sec_dhcpv6_ext_relay" numbered="true"
	       toc="default">

        <name>Address Assignment from the Preferred SLAP Quadrant Indicated by the Relay"> Relay</name>
        <t>
Next, we describe the protocol operations for a relay to select a preferred
SLAP quadrant using the DHCPv6 signaling procedures described in <xref
target="I-D.ietf-dhc-mac-assign" />. target="RFC8947" format="default"/>. This is useful when a DHCPv6 server is
operating over a large infrastructure split in different network regions, where
each region might have different requirements. The signaling flow is shown in
<xref target="fig:dhcpv6_flow_relay" />. target="fig_dhcpv6_flow_relay" format="default"/>.
        </t>

        <figure anchor="fig:dhcpv6_flow_relay" title="DHCPv6 signaling flow (client-relay-server)" >
<artwork><![CDATA[ anchor="fig_dhcpv6_flow_relay">
          <name>DHCPv6 Signaling Flow (Client-Relay-Server)</name>
          <artwork name="" type="" align="left" alt=""><![CDATA[
+--------+                  +--------+                     +--------+
| DHCPv6 |                  | DHCPv6 |                     | DHCPv6 |
| client |                  | relay  |                     | server |
+--------+                  +--------+                     +--------+
   |                            |                                |
   +-----1. Solicit(IA_LL)----->|                                |
   |                            +----2. Relay-forward            |
   |                            |    (Solicit(IA_LL),QUAD)------>|
   |                            |                                |
   |                            |<---3. Relay-reply              |
   |                            |    (Advertise(IA_LL(LLADDR)))--+
   |<4. Advertise(IA_LL(LLADDR))+                                |
   |-5. Request(IA_LL(LLADDR))->|                                |
   |                            +-6. Relay-forward               |
   |                            | (Request(IA_LL(LLADDR)),QUAD)->|
   |                            |                                |
   |                            |<--7. Relay-reply               |
   |                            |   (Reply(IA_LL(LLADDR)))-------+
   |<--8. Reply(IA_LL(LLADDR))--+                                |
   |                            |                                |
   ·                            ·                                ·
   ·
   .                            .                                .
   .                    (timer expiring)                         ·
   ·                            ·                                ·                         .
   .                            .                                .
   |                            |                                |
   +--9. Renew(IA_LL(LLADDR))-->|                                |
   |                            |--10. Relay-forward             |
   |                            |  (Renew(IA_LL(LLADDR)),QUAD)-->|
   |                            |                                |
   |                            |<---11. Relay-reply             |
   |                            |     (Reply(IA_LL(LLADDR)))-----+
   |<--12. Reply(IA_LL(LLADDR)--+ Reply(IA_LL(LLADDR))-+                                |
   |                            |                                |
]]></artwork>
        </figure>

        <t>
          <list style="numbers">

            <t>
        <ol spacing="normal" type="1"><li>
Link-layer addresses (i.e., MAC addresses) are assigned in blocks. The smallest
block is a single address. To request an assignment, the client sends a Solicit
message with an IA_LL option in the message. The IA_LL option MUST <bcp14>MUST</bcp14> contain a an
LLADDR option.
            </t>

            <t>
            </li>
          <li>
The DHCP relay receives the Solicit message and encapsulates it in a
Relay-forward message. The relay, based on local knowledge and policies,
includes in the Relay-forward message the QUAD option with the preferred
quadrant. The relay might know which quadrant to request based on local
configuration (e.g., the served network contains IoT devices only, thus
requiring ELI/SAI) or other means. Note that if a client sends multiple
instances of the IA_LL option in the same message, the DHCP relay MAY <bcp14>MAY</bcp14> only
add a single instance of the QUAD option.
            </t>

            <t>
            </li>
          <li>
Upon receiving a relayed message containing an IA_LL option, the server inspects
the contents for instances of OPTION_SLAP_QUAD in both the Relay Forward Relay-forward message
and the client's message payload. Depending on the server's policy, the
instance of the option to process is selected (see also at the end of this
section). For each of the entries in OPTION_SLAP_QUAD, in order of the
preference field (highest to lowest), the server checks if it has a configured
MAC address pool matching the requested quadrant identifier, identifier and an available
range of addresses of the requested size. If suitable addresses are found, the
server sends back an Advertise message with an IA_LL option containing an LLADDR
option that specifies the addresses being offered. This message is sent to the
Relay in a Relay-reply message. If the server supports the semantics of the
preferred quadrant included in the QUAD option, option and manages a block of addresses
belonging to a requested quadrant, then the addresses being offered MUST <bcp14>MUST</bcp14>
belong to a requested quadrant. The server SHOULD <bcp14>SHOULD</bcp14> apply the contents of the
relay's supplied QUAD option for all of the client's IA_LLs, unless configured
to do otherwise.
            </t>

            <t>
            </li>
          <li>
The relay sends the received Advertise message to the client.
            </t>

            <t>
            </li>
          <li>
The client waits for available servers to send Advertise responses and picks one
server
server, as defined in Section 18.2.9 of <xref target="RFC8415"
/>. section="18.2.9" sectionFormat="of"/>. The client then sends a Request message that includes the IA_LL container
option with the LLADDR option copied from the Advertise message sent by the
chosen server.
            </t>

            <t>
            </li>
          <li>
The relay forwards the received Request in a Relay-forward message. It adds adds, in the
Relay-forward
Relay-forward, a QUAD IA_LL-option IA_LL option with the preferred quadrant.
            </t>

            <t>
            </li>
          <li>
Upon reception of the forwarded Request message with IA_LL container option, the
server assigns requested addresses. The server MAY <bcp14>MAY</bcp14> alter the allocation at this
time. It then generates and sends a Reply message, message in a Relay-reply
message back to the
relay.
            </t>

            <t>
            </li>
          <li>
Upon receiving a Reply message, the client parses the IA_LL container option and
may start using all provided addresses.
            </t>

            <t>
            </li>
          <li>
The client is expected to periodically renew the link-layer addresses addresses, as
governed by T1 and T2 timers. This mechanism can be administratively disabled by
the server sending "infinity" as the T1 and T2 values (see Section 7.7 of <xref target="RFC8415" />). section="7.7" sectionFormat="of"/>). The client sends a Renew option after T1.
            </t>

            <t>
            </li>
          <li>
This message is forwarded by the relay in a Relay-forward message, including a QUAD
IA_LL-option
IA_LL option with the preferred quadrant.
            </t>

            <t>
            </li>
          <li>
The server responds with a Reply message, including an LLADDR option with
extended lifetime. This message is sent in a Relay-reply message.
            </t>

            <t>
            </li>
          <li>
The relay sends the Reply message back to the client.
            </t>

          </list>

        </t>
            </li>
        </ol>
        <t>
The server SHOULD <bcp14>SHOULD</bcp14> implement a configuration parameter to deal with the with&nbsp;the case
where the client's DHCP message contains an instance of OPTION_SLAP_QUAD, OPTION_SLAP_QUAD and
the relay adds a second instance in its relay-forward Relay-forward message. This parameter
configures the server to process either the client's, client's or the relay's instance of
option QUAD. It is RECOMMENDED <bcp14>RECOMMENDED</bcp14> that the default for such a parameter is to
process the client's instance of the option.
        </t>
        <t>
The client MAY <bcp14>MAY</bcp14> check if the received MAC address belongs to a quadrant it is
willing to use/configure, use/configure and MAY <bcp14>MAY</bcp14> decide based on that whether to use configure use/configure
the received address.
        </t>
      </section>
    </section>
    <section anchor="sec:dhcpv6_options" title="DHCPv6 anchor="sec_dhcpv6_options" numbered="true" toc="default">
      <name>DHCPv6 Option Definition"> Definition</name>
      <section anchor="sec:quad_IA_LL"
               title="Quad option"> anchor="sec_quad_IA_LL" numbered="true" toc="default">
        <name>QUAD Option</name>
        <t>
The QUAD option is used to specify the preferences for the selected quadrants
within an IA_LL. The option MUST either <bcp14>MUST</bcp14> be encapsulated either in the IA_LL-options
field of an IA_LL option or in a Relay-forward message.
        </t>
        <t>
The format of the QUAD option is:
        </t>
        <figure align="center" anchor="quad-option"
              title="Quad anchor="quad-option">
          <name>QUAD Option Format"> Format</name>
          <artwork align="left"><![CDATA[ align="left" name="" type="" alt=""><![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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |       OPTION_SLAP_QUAD        |          option-len           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |   quadrant-1  |    pref-1     |   quadrant-2  |    pref-2     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   .                                                               .
   .                                                               .
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |  quadrant-n-1 |   pref-n-1    |   quadrant-n  |    pref-n     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
           ]]></artwork>
        </figure>

        <t>
          <list hangIndent="16" style="hanging">
            <t hangText="option-code">
        <dl newline="false" spacing="normal" indent="16">
          <dt>option-code</dt>
          <dd>
OPTION_SLAP_QUAD (IANA-1).
            </t>

            <t hangText="option-len"> (140).
            </dd>
          <dt>option-len</dt>
          <dd>
2 * number of included (quadrant, preference). A This is a 2-byte field containing the
total length of all (quadrant, preference) pairs included in the option.
            </t>

            <t hangText="quadrant-n">
            </dd>
          <dt>quadrant-n</dt>
          <dd>
Identifier of the quadrant (0: AAI, 1: ELI, 2: Reserved by IEEE
<xref target="IEEEStd802c" />, format="default"/>, and 3: SAI). Each quadrant
MUST
<bcp14>MUST</bcp14> only appear once at most in the option. A This is a 1-byte field.
            </t>

            <t hangText="pref-n">
            </dd>
          <dt>pref-n</dt>
          <dd>
Preference associated to quadrant-n. A higher value means a more preferred
quadrant. A This is a 1-byte field.
            </t>

          </list>

        </t>
            </dd>
        </dl>
        <t>
A quadrant identifier value MUST <bcp14>MUST</bcp14> only appear appear, at most most, once in the option. If
an option option.&nbsp;If
an&nbsp;option includes more than one occurrence of the same quadrant identifier,
only the first occurence occurrence is processed processed, and the rest MUST <bcp14>MUST</bcp14> be ignored by the
server.
        </t>
        <t>
If the same preference value is used for more than one quadrant, the server
MAY
<bcp14>MAY</bcp14> select which quadrant should be preferred (if the server can assign
addresses from all or some of the quadrants with the same assigned
preference). Note that this is not a simple list of quadrants ordered by
preference without with no preference value value, but a list of quadrants with explicit
preference values. This way it can support the case whereby a client really
has no preference between two or three quadrants, leaving the decision to the
server.
        </t>
        <t>
If the client or relay agent provide provides the OPTION_SLAP_QUAD, the server MUST <bcp14>MUST</bcp14> use
the quadrant-n/pref-n values to order the selection of the quadrants. If the
server can provide an assignment from one of the specified quadrants, it SHOULD <bcp14>SHOULD</bcp14>
proceed with the assignment. If the server does not have a configured address
pool matching any of the specified quadrant-n fields, fields or if the server has a
configured address pool of the correct quadrant, quadrant but no available addresses,
it MUST <bcp14>MUST</bcp14> return the IA_LL option containing a status of NoAddrsAvail.
        </t>
        <t>
There is no requirement that the client or relay agent order the quadrant/pref
values in any specific order; hence hence, servers MUST NOT <bcp14>MUST NOT</bcp14> assume that
quadrant-1/pref-1 have the highest preference (except if there is only 1 one set of
values).
        </t>
        <t>
For cases where a server may not be configured to have pools for the client or
relay quadrant preferences, clients and relays SHOULD <bcp14>SHOULD</bcp14> specify all quadrants in
the QUAD option to assure the client gets an address (or addresses) -- if any
are available. Specifying all quadrants also results in a QUAD option supporting
server responding like a non-QUAD option supporting server, i.e., an address (or
addresses) from any available quadrants can be returned.
        </t>
      </section>
    </section>
    <section anchor="IANA" title="IANA Considerations">

      <t>
IANA is requested to assign numbered="true" toc="default">
      <name>IANA Considerations</name>

      <t>IANA has assigned the QUAD (IANA-1) (140)
   option code from the DHCPv6 "Option Codes" subregistry of the
   "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)" registry maintained at
http://www.iana.org/assignments/dhcpv6-parameters and use the following data
when adding the option to the registry:
      </t>

      <figure>
        <artwork align="left">
          <![CDATA[
    Value: IANA-1
    Description: OPTION_SLAP_QUAD
    Client ORO: No
    Singleton Option: No
    Reference: this document
          ]]>
        </artwork>
      </figure>
   <eref target="http://www.iana.org/assignments/dhcpv6-parameters" brackets="angle"/>:</t>

      <dl spacing="compact">
   <dt>Value:</dt><dd>140</dd>
   <dt>Description:</dt><dd>OPTION_SLAP_QUAD</dd>
   <dt>Client ORO:</dt><dd>No</dd>
   <dt>Singleton Option:</dt><dd>Yes</dd>
   <dt> Reference:</dt><dd>RFC 8948</dd>
        </dl>
    </section>
    <section anchor="Security" title="Security Considerations">

      <t>
See <xref target="RFC8415" /> and <xref target="RFC7227" /> for the DHCPv6
security and privacy considerations. See <xref target="RFC8200" /> for the IPv6
security considerations.
      </t>

      <t>
See also <xref target="I-D.ietf-dhc-mac-assign" /> for security considerations
regarding link-layer address assignments using DHCP.
      </t>

    </section>

    <section anchor="Acknowledgments" title="Acknowledgments"> numbered="true" toc="default">
      <name>Security Considerations</name>
      <t>
The authors would like to thank Bernie Volz for his very valuable comments on
this document. We also want to thank Ian Farrer, Tomek Mrugalski, &Eacute;ric
Vyncke, Tatuya Jinmei, Carl Wallace, Ines Robles, Ted Lemon, Jaime Jimenez,
Robert Wilton, Benjamin Kaduk, Barry Leiba, Alvaro Retana, Murray Kucherawy
See <xref target="RFC8415" format="default"/> and
Rob Wilton <xref target="RFC7227" format="default"/> for their very detailed and helpful reviews. And to Roger Marks the DHCPv6
security and
Antonio de la Oliva privacy considerations. See <xref target="RFC8200" format="default"/> for comments related to IEEE work and references. the IPv6
security considerations.
      </t>
      <t>
The work in document draft has been supported by the H2020 5Growth (Grant
856709) and 5G-DIVE projects (Grant 859881).
	Also, see <xref target="RFC8947" format="default"/> for security considerations
regarding link-layer address assignments using DHCP.
      </t>
    </section>
  </middle>
  <back>

    <references title="Normative References">
      &rfc2119;
      &rfc8174;
      &rfc8415;
      &I-D.ietf-dhc-mac-assign;
    <references>
      <name>References</name>
      <references>
        <name>Normative References</name>
        <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.8415.xml"/>
<reference anchor='RFC8947' target="https://www.rfc-editor.org/info/rfc8947">
<front>
<title>Link-Layer Addresses Assignment Mechanism for DHCPv6</title>
<author initials='B' surname='Volz' fullname='Bernie Volz'>
    <organization>Cisco Systems, Inc.</organization>
</author>
<author initials='T' surname='Mrugalski' fullname='Tomek Mrugalski'>
    <organization>Internet Systems Consortium, Inc.</organization>
</author>
<author initials='CJ' surname='Bernardos' fullname='Carlos J. Bernardos'>
    <organization>Universidad Carlos III de Madrid</organization>
</author>
<date month='November' year='2020'/>
</front>
<seriesInfo name="RFC" value="8947"/>
<seriesInfo name="DOI" value="10.17487/RFC8947"/>
</reference>

      </references>

    <references title="Informative References">

      &rfc8200;
      <references>
        <name>Informative References</name>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.8200.xml"/>

        <reference anchor="IEEEStd802c">
          <front>
            <title>
              IEEE Standard for Local and Metropolitan Area Networks: Overview
	      and Architecture, Architecture -- Amendment 2: Local Medium Access Control (MAC) Address Usage, IEEE Std 802c-2017 Usage
            </title>
            <author>
              <organization>IEEE</organization>
            </author>
            <date month="June" year="2017" /> month="August" year="2017"/>
          </front>
	  <seriesInfo name="IEEE Std" value="802c-2017"/>
	  <seriesInfo name="DOI" value="10.1109/IEEESTD.2017.8016709"/>
        </reference>

        <reference anchor="IEEEStd802">
          <front>
            <title>
              IEEE Standard for Local and
              Metropolitan Area Networks: Overview and Architecture, IEEE Std 802-2014 Architecture
            </title>
            <author>
              <organization>IEEE</organization>
            </author>
            <date month="June" year="2014" /> year="2014"/>
          </front>
	  <seriesInfo name="IEEE Std" value="802-2014"/>
	  <seriesInfo name="DOI" value="10.1109/IEEESTD.2014.6847097"/>
        </reference>

        <reference anchor="IEEE-P802.1CQ-Project"> anchor="IEEE-P802.1CQ-Project" target="https://standards.ieee.org/project/802_1CQ.html">
          <front>
            <title>
              IEEE P802.1CQ:
             P802.1CQ - Standard for Local and Metropolitan Area Networks:
	     Multicast and Local Address Assignment
            </title>
            <author>
              <organization>IEEE</organization>
            </author>

          <date />
          </front>
        </reference>

      &rfc7228;
      &rfc7548;
      &rfc7227;
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7228.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7548.xml"/>
        <xi:include href="https://xml2rfc.ietf.org/public/rfc/bibxml/reference.RFC.7227.xml"/>
      </references>
    </references>
    <section anchor="sec:quadrant_selection" title="Quadrant anchor="sec_quadrant_selection" numbered="true" toc="default">
      <name>Example Uses of Quadrant Selection Mechanisms examples"> Mechanisms</name>
      <t>
This appendix describes some examples of how the quadrant preference mechanisms
could be used.
      </t>
      <t>
Let's
First, let's take first an IoT scenario as an example. An IoT device might decide on
its own the SLAP quadrant it wants to use to obtain a local MAC address, using
the following information to take make the decision:

          <list style="symbols">

            <t>
Type

      </t>

      <ul spacing="normal">
	<li>Type of IoT deployment: e.g., For example, industrial, domestic, rural, etc. For small
deployments, such as domestic ones, the IoT device itself can decide to use the AAI
quadrant (this might not even involve the use of DHCP, by the device just
configuring a random address computed by the device itself). For large
deployments, such as industrial or rural ones, where thousands of devices
might co-exist, coexist, the IoT can decide to use the ELI or SAI quadrants.
            </t>

            <t>
Mobility: if quadrants.</li>

<li>Mobility: If the IoT device can move, then it might prefer to select the SAI
or AAI quadrants to minimize address collisions when moving to another network.
If the device is known to remain fixed, then the ELI is probably the most
suitable one to use.
            </t>

            <t>
Managed/unmanaged: depending use.</li>

<li>Managed/Unmanaged: Depending on whether the IoT device is managed during its
lifetime or cannot be re-configured reconfigured <xref target="RFC7548" />, format="default"/>, the decision of
what quadrant is more appropriate might be different. For example, if the IoT
device can be managed (e.g., configured), configured) and network topology changes might
occur during its lifetime (e.g., due to changes on the deployment, such as
extensions involving additional devices), this has an impact on the preferred
quadrant (e.g., to avoid potential collisions in the future).
            </t>

            <t>
Operation/battery lifetime: depending future).</li>

<li>Operation / Battery Lifetime: Depending on the expected lifetime of the device device, a
different quadrant might be preferred (as before, to minimize potential address
collisions in the future).
            </t>

          </list> future).</li>
      </ul>

      <t>
The previous parameters are considerations that the device vendor/administrator
may wish to use when defining the IoT device’s MAC address device's MAC&nbsp;address request policy (i.e.,
how to select a given SLAP quadrant). IoT devices are typically very resource
constrained, so there may only be a simple decision-making process based on
pre-configured
preconfigured preferences.
      </t>
      <t>
We now take the WiFi Wi-Fi device scenario, considering considering, for example example, that a laptop
or smartphone connects to a network using its built in built-in MAC address. Due to
privacy/security concerns, the device might want to configure a local MAC
address. The device might use different parameters and context information to
decide, not only which SLAP quadrant to use for the local MAC address
configuration, but also when to perform a change of address (e.g., it might be
needed to change address several times). This information includes, but it is
not limited to:

          <list style="symbols">

            <t>

      </t>
      <ul spacing="normal">
        <li>
Type of network the device is connected: public, work, home.
            </t>

            <t>
            </li>
        <li>
Trusted network: Yes/No.
            </t>

            <t>
            </li>
        <li>
First time visited network: Yes/No.
            </t>

            <t>
            </li>
        <li>
Network geographical location.
            </t>

            <t>
            </li>
        <li>
Mobility: Yes (the device might change its network attachment point)/No point) / No (the
device is not going to change its network attachment point).
            </t>

            <t>
            </li>
        <li>
Operating System (OS) network profile, including security/trust related security/trust-related
parameters: most Most modern OSs keep metadata associated to with the networks they can
attach to, as to as, for example example, the level of trust the user or administrator assigns
to the network. This information is used to configure how the device behaves in
terms of advertising itself on the network, firewall settings, etc.

But this information can also be used to decide whether or not to configure a
local MAC address
or not, address, from which SLAP quadrant it should be assigned, and how often.
            </t>

            <t>
often it may be assigned.
            </li>
        <li>
Triggers coming from applications regarding location privacy. privacy: An app might
request to that the OS to maximize location privacy (due to the nature of the
application)
application), and this might require that the OS forces to force the use of a local MAC
address,
address or that the local MAC address is to be changed.
            </t>

          </list>

        </t>
            </li>
      </ul>
      <t>
This information can be used by the device to select the SLAP quadrant. For
example, if the device is moving around (e.g., while connected to a public
network in an airport), it is likely that it might change access point points several
times, and therefore
times; therefore, it is best to minimize the chances of address collision,
using the SAI or AAI quadrants. If the device is not expected to move
and is attached to a
trusted network (e.g. (e.g., in some scenarios at work), then it is probably best to select the ELI
quadrant. These are just some examples of how to use this information to select
the quadrant.
      </t>
      <t>
Additionally, the information can also be used to trigger subsequent changes of
MAC address, address to enhance location privacy. Besides, changing the SLAP
quadrant might also be used as an additional enhancement to make it harder to track
the user location.
      </t>
      <t>
Last, if we consider the data center data-center scenario, a hypervisor might request local
MAC addresses to be assigned to virtual machines. As in the previous scenarios,
the hypervisor might select the preferred SLAP quadrant using information
provided by the cloud management system or virtualization infrastructure
manager running on top of the hypervisor. This information might include,
but is not limited to:

          <list style="symbols">

            <t>

      </t>
      <ul spacing="normal">
        <li>
Migratable VM. VM: If the function implemented by the VM is subject to be moved to
another physical server or not. This not, this has an impact on the preference for the
SLAP quadrant, as the ELI and SAI quadrants are better suited for supporting
migration in a large data center.
            </t>

            <t>
            </li>
        <li>
VM connectivity characteristics , e.g., characteristics: For example, standalone, part of a pool, and part of a
service graph/chain. If the connectivity characteristics of the VM are known,
this can be used by the hypervisor to select the best SLAP quadrant.
            </li>
      </ul>
    </section>
    <section anchor="Acknowledgments" numbered="false" toc="default">
      <name>Acknowledgments</name>
      <t>
The authors would like to thank <contact fullname="Bernie Volz"/> for
his very valuable comments on this document. We also want to thank
<contact fullname="Ian Farrer"/>, <contact fullname="Tomek
Mrugalski"/>, <contact fullname="Éric Vyncke"/>, <contact
fullname="Tatuya Jinmei"/>, <contact fullname="Carl Wallace"/>,
<contact fullname="Ines Robles"/>, <contact fullname="Ted Lemon"/>,
<contact fullname="Jaime Jimenez"/>, <contact fullname="Robert Wilton"/>,
<contact fullname="Benjamin Kaduk"/>,
<contact fullname="Barry Leiba"/>, <contact fullname="Alvaro
Retana"/>, and
<contact fullname="Murray Kucherawy"/>
for their very detailed and helpful reviews. And thanks to <contact fullname="Roger
Marks"/> and <contact fullname="Antonio de la Oliva"/> for comments related to
IEEE work and references.
      </t>

          </list>
      <t>
The work in this document has been supported by the H2020 5GROWTH (Grant
856709) and 5G-DIVE projects (Grant 859881).
      </t>
    </section>
  </back>
</rfc>