One document matched: draft-zhang-pce-hierarchy-extensions-03.xml
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<rfc category="std" docName="draft-zhang-pce-hierarchy-extensions-03" ipr="trust200902" >
<front>
<title abbrev="PCEP Extensions for H-PCE">Extensions to Path Computation Element Communication Protocol (PCEP) for Hierarchical Path Computation Elements (PCE)</title>
<author fullname="Fatai Zhang" initials="F." surname="Zhang" role="editor" >
<organization>Huawei</organization>
<address>
<postal>
<street>Huawei Base, Bantian, Longgang District</street>
<city>Shenzhen</city>
<region></region>
<code>518129</code>
<country>China</country>
</postal>
<phone>+86-755-28972912</phone>
<email>zhangfatai@huawei.com</email>
</address>
</author>
<author fullname="Quintin Zhao" initials="Q." surname="Zhao">
<organization>Huawei</organization>
<address>
<postal>
<street>125 Nagog Technology Park</street>
<city>Acton</city>
<region>MA</region>
<code> 01719</code>
<country>US</country>
</postal>
<phone></phone>
<email>qzhao@huawei.com</email>
</address>
</author>
<author fullname="Oscar Gonzalez de Dios" initials="O." role="editor" surname="Gonzalez de Dios">
<organization>Telefonica I+D</organization>
<address>
<postal>
<street>Don Ramon de la Cruz 82-84</street>
<city>Madrid</city>
<region></region>
<code>28045</code>
<country>Spain</country>
</postal>
<phone>+34913128832</phone>
<email>ogondio@tid.es</email>
</address>
</author>
<author fullname="Ramon Casellas" initials="R." surname="Casellas">
<organization>CTTC</organization>
<address>
<postal>
<street>Av. Carl Friedrich Gauss n.7</street>
<city>Castelldefels</city>
<region></region>
<code>Barcelona</code>
<country>Spain</country>
</postal>
<phone>+34 93 645 29 00</phone>
<email>ramon.casellas@cttc.es</email>
</address>
</author>
<author fullname="Daniel King" initials="D." surname="King">
<organization>Old Dog Consulting</organization>
<address>
<postal>
<street></street>
<city></city>
<region></region>
<code></code>
<country>UK</country>
</postal>
<phone></phone>
<email>daniel@olddog.co.uk</email>
</address>
</author>
<!-- date day="24" month="April" year="2012" or autocompleted -->
<date year="2013" />
<area>Routing</area>
<workgroup>Network Working Group</workgroup>
<keyword>H-PCE</keyword>
<keyword>PCE</keyword>
<keyword>PCEP</keyword>
<keyword>inter-domain</keyword>
<abstract>
<t>The Hierarchical Path Computation Element (H-PCE) architecture, defined in the companion framework document [RFC6805], provides a mechanism to allow the optimum sequence of domains to be selected, and the optimum end-to-end path to be derived through the use of a hierarchical relationship between domains.</t>
<t>This document defines the Path Computation Element Protocol (PCEP) extensions for the purpose of implementing Hierarchical PCE procedures which are described in the aforementioned document.</t>
</abstract>
</front>
<middle>
<!-- ===================================================================
Introduction
=================================================================== -->
<section title="Introduction">
<t><xref target="RFC6805"/> describes a Hierarchical PCE (H-PCE) architecture which can be used for computing end-to-end paths for inter-domain MPLS Traffic Engineering (TE) and GMPLS Label Switched Paths (LSPs).</t>
<t> Within the hierarchical PCE architecture, the parent PCE is used to compute a multi-domain path based on the domain connectivity information. A child PCE may be responsible for a single domain or multiple domains, it is used to compute the intra-domain path based on its domain topology information.</t>
<t> The H-PCE end-to-end domain path computation procedure is described below:
<list style="symbols">
<t>A path computation client (PCC) sends the inter-domain path computation requests to the child PCE responsible for its domain;</t>
<t>The child PCE forwards the request to the parent PCE;</t>
<t>The parent PCE computes the likely domain paths from the ingress domain to the egress domain;</t>
<t>The parent PCE sends the intra-domain path computation requests (between the domain border nodes) to the child PCEs which are responsible for the domains along the domain path;</t>
<t>The child PCEs return the intra-domain paths to the parent PCE;</t>
<t>The parent PCE constructs the end-to-end inter-domain path based on the intra-domain paths;</t>
<t>The parent PCE returns the inter-domain path to the child PCE;</t>
<t>The child PCE forwards the inter-domain path to the PCC;</t>
</list>
</t>
<t>In addition, the parent PCE may be requested to provide only the sequence of domains to a child PCE so that alternative inter-domain path computation procedures, including Per Domain (PD) <xref target="RFC5152"/> and Backwards Recursive Path Computation (BRPC) <xref target="RFC5441"/> may be used.</t>
<t>This document defines the PCEP extensions for the purpose of implementing Hierarchical PCE procedures, which are described in <xref target="RFC6805"/>.</t>
<section title="Scope">
<t>The following functions are out of scope of this document.
<list style="symbols">
<t>Finding end point addresses;</t>
<t>Parent Traffic Engineering Dabase (TED) methods;</t>
<t>Domain connectivity;</t>
</list>
</t>
<t>The document also uses a number of [editor notes] to describe options and alternative solutions. These options and notes will be removed before publication once agreement is reached.</t>
</section>
<!-- ===================================================================
Terminology
=================================================================== -->
<section title="Terminology">
<t>This document uses the terminology defined in <xref target="RFC4655"/>, <xref target="RFC5440"/>
and the additional terms defined in section 1.4 of <xref target="RFC6805"/>.</t>
</section>
<!-- ===================================================================
Requirements Language
=================================================================== -->
<section title="Requirements Language">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in <xref target="RFC2119"/>.</t>
</section>
</section>
<!-- ===================================================================
PCEP Extension Requirements
=================================================================== -->
<section title="Requirements for H-PCE">
<t>This section compiles the set of requirements of the PCEP protocol to support the H-PCE architecture and procedures.</t>
<t><xref target="RFC6805"/> identifies high-level requirements of PCEP extensions
required to support the hierarchical PCE model. </t>
<section title="PCEP Requests">
<t>The PCReq messages are used by a PCC or PCE to make a path computation request to a PCE. In order to achieve the full functionality of the H-PCE procedures, the PCReq message needs to include:<list style="symbols">
<t>Qualification of PCE Requests.</t>
<t>Multi-domain Objective Functions (OF).</t>
<t>Multi-domain Metrics.</t>
</list></t>
<section title="Qualification of PCEP Requests">
<t>As described in section 4.8.1 of <xref target="RFC6805"/>, the H-PCE architecture introduces new request qualifications, which are:<list style="symbols">
<t>It MUST be possible for a child PCE to indicate that a request it sends to a parent PCE should be satisfied by a domain sequence only, that is, not by a full end-to-end path. This allows the child PCE to initiate a per-domain (PD) <xref target="RFC5152"/> or a backward recursive path computation (BRPC) <xref target="RFC5441"/>.</t>
<t>As stated in <xref target="RFC6805"/>, section 4.5, if a PCC knows the egress domain, it can supply this information as the path computation request. It SHOULD be possible to specify the destination domain information in a PCEP request, if it is known.</t>
</list>
</t>
</section>
<section title="Multi-domain Objective Functions">
<t>For inter-domain path computation, there are two new objective functions which are defined in section 1.3.1 and 4.1 of <xref target="RFC6805"/>:<list style="symbols">
<t>Minimize the number of domains crossed. A domain can be either an
Autonomous System (AS) or an Internal Gateway Protocol (IGP) area
depending on the type of multi-domain network hierarchical PCE is
applied to.</t>
<t>Disallow domain re-entry.[Editor's note: Disallow domain re-entry may not be an objective function, but an option in the request].</t>
</list></t>
<t>During the PCEP session establishment procedure, the parent PCE needs to be capable of indicating the Objective Functions (OF) capability in the Open message. This capability information may then be announced by child PCEs, and used for selecting the PCE when a PCC wants a path that satisfies one or multiple inter-domain objective functions.</t>
<t>When a PCC requests a PCE to compute an inter-domain path, the PCC needs also to be capable of indicating the new objective functions for inter-domain path. Note that a given child PCE may also act as a parent PCE.</t>
<t>For the reasons described previously, new OF codes need to be defined for the new inter-domain objective functions. Then the PCE can notify its new inter-domain objective functions to the PCC by carrying them in the OF-list TLV which is carried in the OPEN object. The PCC can specify which objective function code to use, which is carried in the OF object when requesting a PCE to compute an inter-domain path.</t>
<t>The proposed solution may need to differentiate between the OF code that is requested at the parent level, and the OF code that is requested at the intra-domain (child domain).</t>
<t>A parent PCE MUST be capable of ensuring homogeneity, across domains, when applying OF codes for strict OF intra-domain requests.</t>
</section>
<section title="Multi-domain Metrics">
<t>For inter-domain path computation, there are several path metrics of interest [Editor's note: Current framework only mentions metric objectives. The metric itself should be also defined]:<list style="symbols">
<t>Domain count (number of domains crossed).</t>
<t>Border Node count.</t>
</list></t>
<t>A PCC may be able to limit the number of domains crossed by applying a limit on these metrics.</t>
</section>
</section>
<section title="Parent PCE Capability Discovery">
<t>Parent and child PCE relationships are likely to be configured. However, as mentioned in <xref target="RFC6805"/>, it would assist network operators if the child and parent PCE could indicate their H-PCE capabilities.</t>
<t>During the PCEP session establishment procedure, the child PCE needs to be capable of indicating to the parent PCE whether it requests the parent PCE capability or not. Also, during the PCEP session establishment procedure, the parent PCE needs to be capable of indicating whether its parent capability can be provided or not.</t>
</section>
<section title="PCE Domain and PCE ID Discovery">
<t>A PCE domain is a single domain with an associated PCE. Although it is possible for a PCE to manage multiple domains. The PCE domain may be an IGP area or AS.</t>
<t>The PCE ID is an IPv4 and/or IPv6 address that is used to reach the parent/child PCE. It is RECOMMENDED to use an address that is always reachable if there is any connectivity to the PCE.</t>
<t>The PCE ID information and PCE domain identifiers may be provided during the PCEP session establishment procedure or the domain connectivity information collection procedure.</t>
</section>
</section>
<section title="PCEP Extensions (Encoding)">
<section title="OPEN object">
<section title="OF Codes">
<t>There are two new OF codes defined here for H-PCE:<list style="symbols">
<t>MTD<list style="symbols">
<t>Name: Minimize the number of Transit Domains.</t>
<t>Objective Function Code: (to be assigned by IANA, recommended 12).</t>
<t>Description: Find a path P such that it passes through the lnumber of transit domains.</t>
</list></t>
<t>MBN<list style="symbols">
<t>Name: Minimize the number of border nodes.</t>
<t>Objective Function Code: (to be assigned by IANA, recommended 13).</t>
<t>Description: Find a path P such that it passes through the least number of border nodes.</t>
</list>
</t>
<t>DDR<list style="symbols">
<t>Name: Disallow Domain Re-entry (DDR)</t>
<t>Objective Function Code: (to be assigned by IANA, recommended 14)</t>
<t>Description: Find a path P such that does not entry a domain more than once.</t>
</list></t>
</list></t>
</section>
<section title="OPEN Object Flags">
<t>There are two OPEN object flags defined here for H-PCE:<list style="symbols">
<t>Parent PCE Request bit (to be assigned by IANA, recommended bit 0): if set, it would signal that the child PCE wishes to use the peer PCE as a parent PCE.</t>
<t>Parent PCE Indication bit (to be assigned by IANA, recommended bit 1): if set, it would signal that the PCE can be used as a parent PCE by the peer PCE.</t>
</list></t>
</section>
<section title="Domain-ID TLV">
<t>The type of Domain-ID TLV is to be assigned by IANA (recommended 7).
The length is variable. The format of this TLV is defined below:</t>
<figure anchor="figure_domain_id_tlv" title="Domain-ID TLV">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain ID |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
</figure>
<t>Domain Type (8 bits): Indicates the domain type. Two types of
domain are currently defined:<list style="symbols">
<t>Type=1: the Domain ID field carries an IGP Area ID.</t>
<t>Type=2: the Domain ID field carries an AS number.</t>
</list></t>
<t>Domain ID (variable): Indicates an IGP Area ID or AS number. It can be 2 bytes, 4 bytes or 8 bytes long depending on the domain identifier used.</t>
<t>[Editor's note: draft-dhody-pce-pcep-domain-sequence, section 3.2
deals with the encoding of domain sequences, using ERO-subobjects.
Work is ongoing to define domain identifiers for OSPF-TE areas, IS-IS
area (which are variable sized), 2-byte and 4-byte AS number, and any
other domain that may be defined in the future. It uses RSVP-TE
subobject discriminators, rather than new type 1/ type 2. A domain
sequence may be encoded as a route object. The "VALUE" part of the
TLV could follow common RSVP-TE subobject format:</t>
<figure anchor="figure_alt_domain_id_tlv" title="Alternative Domain-ID TLV">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Type | Length | AS Id (2 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
</figure>
</section>
<section title="PCE-ID TLV">
<t>The type of PCE-ID TLV is to be assigned by IANA (recommended 8). The length is variable. The format of this TLV is defined below:</t>
<figure anchor="pce_id_tlv" title="PCE-ID TLV">
<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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// PCE IP Address //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+]]></artwork>
</figure>
<t>Address Type (16 bits): Indicates the address type of PCE IP Address. 1 means IPv4 address type, 2 means IPv6 address type.</t>
<t>PCE IP Address: Indicates the reachable address of a PCE.</t>
<t>[Editor's note: <xref target="RFC5886"/> already defines the PCE-ID object. If a semantically equivalent PCE-ID TLV is needed (to avoid modifying message grammars to include the object), it can align with the PCEP object: in any case, the length (4 / 16 bytes) can be used to know whether it is an IPv4 or an IPv6 PCE, the address type is not needed.]</t>
</section>
</section>
<section title="RP object">
<section title="RP Object Flags">
<t>The following flags are defined:<list style="symbols">
<t>Domain Path Request bit (to be assigned by IANA, recommended bit 17): if set, it means the child PCE wishes to get the domain sequence.</t>
<t>Destination Domain Query bit (to be assigned by IANA, recommended bit 16): if set, it means the parent PCE wishes to get the destination domain ID.</t>
</list>
</t>
</section>
<section title="Domain-ID TLV">
<t>The format of this TLV is defined in Section 3.1.3. This TLV can be carried in an OPEN object to indicate a (list of) managed domains, or carried in a RP object to indicate the destination domain ID when a child PCE responds to the parent PCE's destination domain query by a PCRep message.</t>
<t>[Editors note. In some cases, the Parent PCE may need to allocate a node which is not necessarily the destination node.]</t>
</section>
</section>
<section title="Metric Object">
<t>There are two new metrics defined in this document for H-PCE:<list style="symbols">
<t>Domain count (number of domains crossed).</t>
<t>Border Node Count (number of border nodes crossed).</t>
</list></t>
</section>
<section title="PCEP-ERROR object">
<section title="Hierarchy PCE Error-Type">
<t>A new PCEP Error-Type is allocated for hierarchy PCE (to be assigned by IANA, recommended 19):</t>
<figure title="H-PCE error table">
<artwork><![CDATA[
+------------+------------------------------------------------------+
| Error-Type | Meaning |
+------------+------------------------------------------------------+
| 19 | H-PCE error Error-value=1: parent PCE capability |
| | cannot be provided |
+------------+------------------------------------------------------+]]></artwork>
</figure>
</section>
</section>
<section title="NO-PATH Object">
<t>To communicate the reason(s) for not being able to find a multi-
domain path or domain sequence, the NO-PATH object can be used in
the PCRep message. <xref target="RFC5440"/> defines the format of the NO-PATH
object. The object may contain a NO-PATH-VECTOR TLV to provide
additional information about why a (domain) path computation has
failed.</t>
<t>Three new bit flags are defined to be carried in the Flags field in
the NO-PATH-VECTOR TLV carried in the NO-PATH Object.<list style="symbols">
<t>Bit 23(to be assigned by IANA): When set, the parent PCE indicates
that destination domain unknown;</t>
<t>Bit 22(to be assigned by IANA): When set, the parent PCE indicates
un-responsive child PCE(s);</t>
<t>Bit 21(to be assigned by IANA): When set, the parent PCE indicates
no available resource available in one or more domain(s).</t>
</list></t>
</section>
</section>
<section title="H-PCE Procedures">
<section title="OPEN Procedure between Child PCE and Parent PCE">
<t> If a child PCE wants to use the peer PCE as a parent, it can set the parent PCE request bit in the OPEN object carried in the Open message during the PCEP session creation procedure. If the peer PCE does not want to provide the parent function to the child PCE, it must send a PCErr message to the child PCE and clear the parent PCE indication bit in the OPEN object.</t>
<t> If the parent PCE can provide the parent function to the peer PCE, it may set the parent PCE indication bit in the OPEN object carried in the Open message during the PCEP session creation procedure.</t>
<t>The PCE may also report its PCE ID and list of domain ID to the peer PCE by specifying them in the PCE-ID TLV and List of Domain-ID TLVs in the OPEN object carried in the Open message during the PCEP session creation procedure.</t>
<t> The OF codes defined in this document can be carried in the OF-list TLV of the OPEN object. If the OF-list TLV carries the OF codes, it means that the PCE is capable of implementing the corresponding objective functions. This information can be used for selecting a proper parent PCE when a child PCE wants to get a path that satisfies a certain objective function.</t>
<t>When a specific child PCE sends a PCReq to a peer PCE that requires parental activity and the peer PCE does not want to act as the parent for it, the peer PCE should send a PCErr message to the child PCE and specify the error-type (IANA) and error-value (1) in the PCEP-ERROR object.</t>
</section>
<section title="Procedure to obtain Domain Sequence">
<t>If a child PCE only wants to get the domain sequence for a multi-domain path computation from a parent PCE, it can set the Domain Path Request bit in the RP object carried in a PCReq message. The parent PCE which receives the PCReq message tries to compute a domain sequence for it. If the domain path computation succeeds the parent PCE sends a PCRep message which carries the domain sequence in the ERO to the child PCE. The domain sequence is specified as AS or AREA ERO sub-objects (type 32 for AS <xref target="RFC3209"/> or a to-be-defined IGP area type). Otherwise it sends a PCReq message which carries the NO-PATH object to the child PCE.</t>
</section>
</section>
<section title="Error Handling">
<t>A PCE that is capable of acting as a parent PCE might not be
configured or willing to act as the parent for a specific child PCE.
This fact could be determined when the child sends a PCReq that
requires parental activity (such as querying other child PCEs), and
could result in a negative response in a PCEP Error (PCErr) message
and indicate the hierarchy PCE error types.</t>
<t>Additionally, the parent PCE may fail to find the multi-domain path
or domain sequence due to one or more of the following reasons:<list style="symbols">
<t>A child PCE cannot find a suitable path to the egress;</t>
<t>The parent PCE do not hear from a child PCE for a specified time;</t>
<t>The objective functions specified in the path request cannot be met.</t>
</list></t>
<t>In this case, the parent PCE MAY need to send a negative path
computation reply specifying the reason. This can be achieved by
including NO-PATH object in the PCRep message. Extension to NO-PATH
object is needed to include the aforementioned reasons.</t>
</section>
<section title="Manageability Considerations">
<t>TBD.</t>
</section>
<section title="IANA Considerations">
<t>As per <xref target="RFC5226"/>, IANA is requested to create/update the following registries</t>
<section title="Objective Function (OF) codes">
<texttable>
<ttcol align="center">Value</ttcol> <ttcol align="center">Meaning</ttcol> <ttcol align="center">Reference</ttcol>
<c>12</c> <c>MBN</c> <c>This document</c>
<c>13</c> <c>MTD</c> <c>This document</c>
<c>14</c> <c>DDR</c> <c>This document</c>
</texttable>
</section>
<section title="OPEN Object Flags">
<texttable>
<ttcol align="center">Bit Number</ttcol> <ttcol align="center">Meaning</ttcol> <ttcol align="center">Reference</ttcol>
<c>0</c> <c>Parent PCE Request</c> <c>This document</c>
<c>1</c> <c>Parent PCE Indication</c> <c>This document</c>
</texttable>
</section>
<section title="RP Object Flags">
<texttable>
<ttcol align="center">Bit Number</ttcol> <ttcol align="center">Meaning</ttcol> <ttcol align="center">Reference</ttcol>
<c>17</c> <c>Domain Path Request</c> <c>This document</c>
</texttable>
</section>
<section title="PCEP TLVs">
<texttable>
<ttcol align="center">Value</ttcol> <ttcol align="center">Meaning</ttcol> <ttcol align="center">Reference</ttcol>
<c>x</c> <c>Interdomain Link TLV</c> <c>This document (section Section 3.3.2)</c>
<c>x</c> <c>Interdomain Node TLV</c> <c>This document (section Section 3.3.3)</c>
</texttable>
</section>
<section title="PCEP PCEP-ERROR types">
<texttable style="none">
<ttcol align="center">Type</ttcol> <ttcol align="center">Value</ttcol> <ttcol align="center">Meaning</ttcol>
<c>H-PCE Error 19</c> <c>1</c> <c>parent PCE capability cannot be provided</c>
<c> </c> <c>2</c> <c>TBD</c>
<c> </c> <c>3</c> <c>TBD</c>
</texttable>
</section>
<section title="New No-Path Reasons">
<texttable>
<ttcol align="center">Bit Number</ttcol> <ttcol align="center">Name</ttcol> <ttcol align="center">Reference</ttcol>
<c>23</c> <c>destination domain unknown</c> <c>This document</c>
<c>22</c> <c>un-responsive child PCE(s)</c> <c>This document</c>
<c>21</c> <c>no resource available in some domains</c> <c>This document </c>
</texttable>
</section>
</section>
<!-- ===================================================================
SECURITY CONSIDERATIONS
=================================================================== -->
<section title="Security Considerations">
<t> To be added.</t>
</section>
<!-- ===================================================================
CONTRIBUTING AUTHORS
=================================================================== -->
<section title="Contributing Authors">
<t>
<list>
<t>
Xian Zhang<vspace blankLines='0'/>
Huawei<vspace blankLines='0'/>
zhang.xian@huawei.com<vspace blankLines='0'/>
</t>
</list>
</t>
</section>
<!-- ===================================================================
ACKNOWLEDGEMENTS
=================================================================== -->
<section title="Acknowledgments">
<t> To be added.</t>
</section>
</middle>
<back>
<references title="Normative References">
&RFC2119;
&RFC3209;
&RFC4655;
&RFC5152;
&RFC5226;
&RFC5316;
&RFC5392;
&RFC5440;
&RFC5441;
&RFC5886;
&RFC6805;
</references>
</back>
</rfc>| PAFTECH AB 2003-2026 | 2026-04-24 04:37:56 |