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Versions: (draft-oki-pce-inter-layer-ext) 00 01 02 03 04 05 06 07 08 09 10 11 12 RFC 8282

Network Working Group                                             E. Oki
Internet-Draft                                                 UEC Tokyo
Intended status: Standards Track                         Tomonori Takeda
                                                                     NTT
                                                             J-L Le Roux
                                                          France Telecom
                                                               A. Farrel
                                                      Old Dog Consulting
                                                             Fatai Zhang
                                                                  Huawei
Expires: December 17, 2011                                 June 17, 2011




     Extensions to the Path Computation Element communication Protocol
         (PCEP) for Inter-Layer MPLS and GMPLS Traffic Engineering

                   draft-ietf-pce-inter-layer-ext-05.txt


Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with
   the provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as Internet-
   Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/ietf/1id-abstracts.txt.

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html.

   This Internet-Draft will expire on December 17, 2011.



Abstract




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   The Path Computation Element (PCE) provides path computation
   functions in support of traffic engineering in Multiprotocol Label
   Switching (MPLS) and Generalized MPLS (GMPLS) networks.

   MPLS and GMPLS networks may be constructed from layered service
   networks. It is advantageous for overall network efficiency to
   provide end-to-end traffic engineering across multiple network layers
   through a process called inter-layer traffic engineering. PCE is a
   candidate solution for such requirements.

   The PCE communication Protocol (PCEP) is designed as a communication
   protocol between Path Computation Clients (PCCs) and PCEs. This
   document presents PCEP extensions for inter-layer traffic engineering.

Conventions used in this document

   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].

Table of Contents


   1. Introduction.................................................3
   2. Overview of PCE-Based Inter-Layer Path Computation...........4
   3. Protocol Extensions..........................................4
      3.1. INTER-LAYER Object......................................4
      3.2. SWITCH-LAYER Object.....................................7
      3.3. REQ-ADAP-CAP Object.....................................8
      3.4. New Metric Types........................................9
      3.5. ERO sub-object.........................................10
   4. Procedures..................................................10
      4.1. Path Computation Request...............................10
      4.2. Path Computation Reply.................................11
   5. Updated Format of PCEP Messages.............................12
   6. Manageability Considerations................................13
   7. IANA Considerations.........................................13
      7.1. New PCEP Objects.......................................13
      7.2. New Registry for INTER-LAYER Object Flags..............14
      7.3. METRIC Type............................................14
   8. Security Considerations.....................................15
   9. Acknowledgments.............................................15
   10. References.................................................15
      10.1. Normative References..................................15
      10.2. Informative References................................16
   11. Authors' Addresses.........................................16



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1. Introduction

   The Path Computation Element (PCE) defined in [RFC4655] is an entity
   that is capable of computing a network path or route based on a
   network graph, and applying computational constraints. A Path
   Computation Client (PCC) may make requests to a PCE for paths to be
   computed.

   A network may comprise multiple layers. These layers may represent
   separations of technologies (e.g., packet switch capable (PSC), time
   division multiplex (TDM), lambda switch capable (LSC)) [RFC3945],
   separation of data plane switching granularity levels (e.g., PSC-1
   and  PSC-2, or VC4 and VC12) [RFC5212], or a distinction between
   client and server networking roles (e.g., commercial or
   administrative separation of client and server networks). In this
   multi-layer network, Label Switched Paths (LSPs) in lower layers are
   used to carry higher-layer LSPs. The network topology formed by
   lower-layer LSPs and advertised as traffic engineering links (TE
   links) in the higher layer is called a Virtual Network Topology (VNT)
   [RFC5212].

   It is important to optimize network resource utilization globally,
   i.e., taking into account all layers, rather than optimizing resource
   utilization at each layer independently. This allows better network
   efficiency to be achieved. This is what we call inter-layer traffic
   engineering. This includes mechanisms allowing the computation of
   end-to-end paths across layers (known as inter-layer path
   computation), and mechanisms for control and management of the VNT by
   setting up and releasing LSPs in the lower layers [RFC5212].

   PCE can provide a suitable mechanism for resolving inter-layer path
   computation issues. The framework for applying the PCE-based path
   computation architecture to inter-layer traffic engineering is
   described in [RFC5623].

   The PCE communication protocol (PCEP) is designed as a communication
   protocol between PCCs and PCEs and is defined in [RFC5440]. A set of
   requirements for PCEP extensions to support inter-layer traffic
   engineering is described in [PCE-INTER-LAYER-REQ].

   This document presents PCEP extensions for inter-layer traffic
   engineering that satisfy the requirements described in [PCE-INTER-
   LAYER-REQ].




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2. Overview of PCE-Based Inter-Layer Path Computation

   [RFC4206] defines a way to signal a higher-layer LSP which has an
   explicit route that includes hops traversed by LSPs in lower layers.
   The computation of end-to-end paths across layers is called Inter-
   Layer Path Computation.

   A Label Switching Router (LSR) in the higher-layer might not have
   information on the lower-layer topology, particularly in an overlay
   or augmented model [RFC3945], and hence may not be able to compute an
   end-to-end path across layers.

   PCE-based inter-layer path computation consists of using one or more
   PCEs to compute an end-to-end path across layers. This could be
   achieved by relying on a single PCE that has topology information
   about multiple layers and can directly compute an end-to-end path
   across layers considering the topology of all of the layers.
   Alternatively, the inter-layer path computation could be performed
   using multiple cooperating PCEs where each PCE has information about
   the topology of one or more layers (but not all layers) and where the
   PCEs collaborate to compute an end-to-end path.

   As described in [RFC 5339], a hybrid nodes may advertise a single TE
   link with multiple switching capabilities. Those TE links exist at
   the layer/region boarder normally. In this case, PCE needs to be
   capable of specifying the server layer path information when the
   server layer path information is required to be returned to the PCC.

   [RFC5623] describes models for inter-layer path computation in more
   detail.

3. Protocol Extensions

   This section describes PCEP extensions for inter-layer path
   computation. Three new objects are defined: the INTER-LAYER object,
   the SWITCH-LAYER object, and the REQ-ADAP-CAP object. Also, two new
   metric types are defined.

3.1. INTER-LAYER Object

   The INTER-LAYER object is optional and can be used in PCReq and PCRep
   messages.

   In a PCReq message, the INTER-LAYER object indicates whether inter-
   layer path computation is allowed, the type of path to be computed,
   and whether triggered signaling (hierarchical LSPs per [RFC4206] or
   stitched LSPs per [RFC5150] depending on physical network


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   technologies) is allowed. When the INTER-LAYER object is absent from
   a PCReq message, the receiving PCE MUST process as though inter-layer
   path computation had been explicitly disallowed (I-bit set to zero -
   see below).

   In a PCRep message, the INTER-LAYER object indicates whether inter-
   layer path computation has been performed, the type of path that has
   been computed, and whether triggered signaling is used.

   When a PCReq message includes more than one request, an INTER-LAYER
   object is used per request. When a PCRep message includes more than
   one path per request that is responded to, an INTER-LAYER object is
   used per path.

   INTER-LAYER Object-Class is to be assigned by IANA (recommended
   value=18)

   INTER-LAYER Object-Type is to be assigned by IANA (recommended
   value=1)

   The format of the INTER-LAYER object body is as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Reserved                                             |T|M|I|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   I flag (1 bit): The I flag is used by a PCC in a PCReq message to
   indicate to a PCE whether an inter-layer path is allowed. When the I
   flag is set (one), the PCE MAY perform inter-layer path computation
   and return an inter-layer path. When the flag is clear (zero), the
   path that is returned MUST NOT be an inter-layer path.

   The I flag is used by a PCE in a PCRep message to indicate to a PCC
   whether the path returned is an inter-layer path. When the I flag is
   set (one), the path is an inter-layer path. When it is clear (zero),
   the path is contained within a single layer either because inter-
   layer path computation was not performed or because a mono-layer path
   (without any virtual TE link and without any loose hop that spans the
   lower-layer network) was found notwithstanding the use of inter-layer
   path computation.

   M flag (1 bit): The M flag is used by a PCC in a PCReq message to
   indicate to a PCE whether mono-layer path or multi-layer path is



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   requested. When the M flag is set (one), multi-layer path is
   requested. When it is clear (zero), mono-layer path is requested.

   The M flag is used by a PCE in a PCRep message to indicate to a PCC
   whether mono-layer path or multi-layer path is returned. When M flag
   is set (one), multi-layer path is returned. When M flag is set (zero),
   mono-layer path is returned.

   If the I flag is clear (zero), the M flag has no meaning and MUST be
   ignored.

   [PCE-INTER-LAYER-REQ] describes two sub-options for mono-layer path.

   - A mono-layer path that is specified by strict hops. The path may
   include virtual TE links.

   - A mono-layer path that includes loose hops that span the lower-
   layer network.

   The choice of this sub-option can be specified by the use of O flag
   in the RP object specified in [RFC5440].

   T flag (1 bit): The T flag is used by a PCC in a PCReq message to
   indicate to a PCE whether triggered signaling is allowed. When the T
   flag is set (one), triggered signaling is allowed. When it is clear
   (zero), triggered signaling is not allowed.

   The T flag is used by a PCE in a PCRep message to indicate to a PCC
   whether triggered signaling is required to support the returned path.
   When the T flag is set (one), triggered signaling is required. When
   it is clear (zero), triggered signaling is not required.

   Note that triggered signaling is used to support hierarchical
   [RFC4206] or stitched [RFC5150] LSPs according to the physical
   attributes of the network layers.

   If the I flag is clear (zero), the T flag has no meaning and MUST be
   ignored.

   Note that the I flag and M flag differ in the following ways. - When
   the I flag is clear (zero), virtual TE links must not be used in path
   computation. In addition, loose hops that span the lower-layer
   network must not be specified. Only regular TE links from the same
   layer may be used.

   - When the I flag is set (one), the M flag is clear (zero), and the T
   flag is set (one), virtual TE links are allowed in path computation.


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   In addition, when the O flag of the RP object is set, loose hops that
   span the lower-layer network may be specified. This will initiate
   lower-layer LSP setup, thus inter-layer path is setup even though the
   path computation result from a PCE to a PCC include hops from the
   same layer only.

   - However, when the I flag is set (one), the M flag is clear (zero),
   and the T flag is clear (zero), since triggered signaling is not
   allowed, virtual TE links must not be used in path computation. In
   addition, loose hops that span the lower-layer network must not be
   specified. Therefore, this is equivalent to the I flag being clear
   (zero).

   Reserved bits of the INTER-LAYER object SHOULD be transmitted as zero
   and SHOULD be ignored on receipt. A PCE that forwards a path
   computation request to other PCEs SHOULD preserve the settings of
   reserved bits in the PCReq messages it sends and in the PCRep
   messages it forwards to PCCs.

3.2. SWITCH-LAYER Object

   The SWITCH-LAYER object is optional on a PCReq message and specifies
   switching layers in which a path MUST, or MUST NOT, be established. A
   switching layer is expressed as a switching type and encoding type.
   The SWITCH-LAYER object MUST NOT be used on a PCReq unless an INTER-
   LAYER object is also present on the PCReq message.

   The SWITCH-LAYER object is optional on a PCRep message, where it is
   used with the NO-PATH object in the case of unsuccessful path
   computation to indicate the set of constraints that could not be
   satisfied.

   SWITCH-LAYER Object-Class is to be assigned by IANA (recommended
   value=19)

   SWITCH-LAYER Object-Type is to be assigned by IANA (recommended
   value=1)

   The format of the SWITCH-LAYER object body is as follows:









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    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | LSP Enc. Type |Switching Type | Reserved                    |I|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                               .                               |
   //                              .                              //
   |                               .                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | LSP Enc. Type |Switching Type | Reserved                    |I|
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   Each row indicates a switching type and encoding type that must or
   must not be used for specified layer(s) in the computed path.

   The format is based on [RFC3471], and has equivalent semantics.

   LSP Encoding Type (8 bits): see [RFC3471] for a description of
   parameters.

   Switching Type (8 bits): see [RFC3471] for a description of
   parameters.

   I flag (1 bit): the I flag indicates whether a layer with the
   specified switching type and encoding type must or must not be used
   by the computed path. When the I flag is set (one), the computed path
   MUST traverse a layer with the specified switching type and encoding
   type. When the I flag is clear (zero), the computed path MUST NOT
   enter or traverse any layer with the specified switching type and
   encoding type.

   When a combination of switching type and encoding type is not
   included in SWITCH-LAYER object, the computed path MAY traverse a
   layer with that combination of switching type and encoding type.

   A PCC may want to specify only a Switching Type and not an LSP
   Encoding Type. In this case, the LSP Encoding Type is set to zero.

3.3. REQ-ADAP-CAP Object

   The REQ-ADAP-CAP object is optional and is used to specify a
   requested adaptation capability for both ends of the lower layer LSP.
   The REQ-ADAP-CAP object is used in a PCReq message for inter-PCE
   communication, where the PCE that is responsible for computing higher
   layer paths acts as a PCC to request a path computation from a PCE
   that is responsible for computing lower layer paths.


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   The REQ-ADAP-CAP object is used in a PCRep message in case of
   unsuccessful path computation (in this case, the PCRep message also
   contains a NO-PATH object, and the REQ-ADAP-CAP object is used to
   indicate the set of constraints that could not be satisfied).

   The REQ-ADAP-CAP object MAY be used in a PCReq message in a mono-
   layer network to specify a requested adaptation capability for both
   ends of the LSP. In this case, it MAY be carried without INTER-LAYER
   Object.

   REQ-ADAP-CAP Object-Class is to be assigned by IANA (recommended
   value=20)

   REQ-ADAP-CAP Object-Type is to be assigned by IANA (recommended
   value=1)

   The format of the REQ-ADAP-CAP object body is as follows:

    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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Switching Cap |   Encoding    | Reserved                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The format is based on [MLN-SOL] and has equivalent semantics.

   Switching Capability (8 bits): see [RFC4203] for a description of
   parameters.

   Encoding (8 bits): see [RFC3471] for a description of parameters.

   A PCC may want to specify a Switching Capability, but not an Encoding.
   In this case, the Encoding MUST be set zero.

3.4. New Metric Types

   Two new metric types are defined for the METRIC object in PCEP.

   Type 11 (suggested value, to be assigned by IANA): Number of
   adaptations on a path.

   Type 12 (suggested value, to be assigned by IANA): Number of layers
   to be involved on a path.





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3.5. ERO sub-object

   A new ERO sub-object named SERVER_LAYER_INFO sub-object is defined in
   this document. This sub-object can be used for specifying the detail
   server layer information of a server layer path, e.g. the switching
   capability and encoding of the server layer path.

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |L|    Type     |     Length    |           Reserved            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    | Switching Cap |   Encoding    |           Reserved            |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    ~                       Optional TLVs                           ~
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   The type of SERVER_LAYER_INFO sub-object is to be assigned by IANA.

   L: The L bit SHOULD NOT be set, so that the subobject represents a
   strict hop in the explicit route.

   Switching Capability (8 bits): see [RFC4203] for a description of
   parameters.

   Encoding (8 bits): see [RFC3471] for a description of parameters.

   Optional TLVs: Optional TLVs may be included within the object to
   specify more specific server layer path information (e.g., traffic
   parameters).

   This sub-object MAY be added immediately behind the node or link
   address sub-objects of the two edge nodes of a service path.

4. Procedures

4.1. Path Computation Request

   A PCC requests or allows inter-layer path computation in a PCReq
   message by including the INTER-LAYER object with the I flag set. The
   INTER-LAYER object indicates whether inter-layer path computation is
   allowed, which path type is requested, and whether triggered
   signaling is allowed.

   The SWITCH-LAYER object, which MUST NOT be present unless the INTER-
   LAYER object is also present, is optionally used to specify the


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   switching types and encoding types that define layers that must, or
   must not, be used in the computed path. When the SWITCH-LAYER object
   is used with the INTER-LAYER object I flag clear (zero), inter-layer
   path computation is not allowed, but constraints specified in the
   SWITCH-LAYER object apply. Example usage includes path computation in
   a single layer GMPLS network.

   The REQ-ADAP-CAP object is optionally used to specify the interface
   switching capability of both ends of the lower layer LSP. The REQ-
   ADAP-CAP object is used in inter-PCE communication, where the PCE
   that is responsible for computing higher layer paths makes a request
   as a PCC to a PCE that is responsible for computing lower layer paths.
   Alternatively, the REQ-ADAP-CAP object may be used in the NMS-VNTM
   model, where the VNTM makes a request as a PCC to a PCE that is
   responsible for computing lower-layer paths.

   The METRIC object is optionally used to specify metric types to be
   optimized or bounded. When metric type 11 (TBC by IANA) is used, it
   indicates that path computation MUST minimize or bound the number of
   adaptations on a path. When metric type 12 (TBC by IANA) is used, it
   indicates that path computation MUST minimize or bound the number of
   layers to be involved on a path.

   Furthermore, in order to allow different objective functions to be
   applied within different network layers, multiple OF objects MAY be
   present. In such a case, the first OF object specifies an objective
   function for the higher-layer network, and subsequent OF objects
   specify objection functions of the subsequent lower-layer networks.

4.2. Path Computation Reply

   In the case of successful path computation, the requested PCE replies
   to the requesting PCC for the inter-layer path computation result in
   a PCRep message that MAY include the INTER-LAYER object. When the
   INTER-LAYER object is included in a PCRep message, the I flag, M flag,
   and T flag indicate semantics of the path as described in Section 3.1.
   Furthermore, when the C flag of the METRIC object in a PCReq is set,
   the METRIC object MUST be included in the PCRep to provide the
   computed metric value, as specified in [RFC5440].

   PCE MAY specify the server layer path information in the ERO. In this
   case, the server layer path information could be demarcated by two
   SERVER_LAYER_INFO sub-objects in the ERO object. The server layer
   path specified in the ERO could be loose or strict. Then the PCC (e.g.
   NMS, ingress node) can trigger the setup of the LSPs according to the
   computed path.



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   In the case of unsuccessful path computation, the PCRep message also
   contains a NO-PATH object, and the SWITCH-TYPE object and/or the REQ-
   ADAP-CAP MAY be used to indicate the set of constraints that could
   not be satisfied.

5. Updated Format of PCEP Messages

   Message formats in this section, as those in [RFC5440] are presented
   using Backus-Naur Format as specified in [RFC5511].

   The format of the PCReq message is updated as follows:

   <PCReq Message>::= <Common Header>
                      [<SVEC-list>]
                      <request-list>

      where:
         <svec-list>::=<SVEC>
                       [<svec-list>]

         <request-list>::=<request>[<request-list>]

         <request>::= <RP>
                      <END-POINTS>
                      [<of-list>]
                      [<LSPA>]
                      [<BANDWIDTH>]
                      [<metric-list>]
                      [<RRO>[<BANDWIDTH>]]
                      [<IRO>]
                      [<LOAD-BALANCING>]
                      [<INTER-LAYER> [<SWITCH-LAYER>]]
                      [<REQ-ADAP-CAP>]
      where:

      <of-list>::=<OF>[<of-list>]
      <metric-list>::=<METRIC>[<metric-list>]

   The format of the PCRep message is updated as follows:
   <PCRep Message> ::= <Common Header>
                       <response-list>




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      where:
         <response-list>::=<response>[<response-list>]

         <response>::=<RP>
                     [<NO-PATH>]
                     [<attribute-list>]
                     [<path-list>]

         <path-list>::=<path>[<path-list>]

         <path>::= <ERO><attribute-list>

      where:
         <attribute-list>::=[<of-list>]
                            [<LSPA>]
                            [<BANDWIDTH>]
                            [<metric-list>]
                            [<IRO>]
                            [<INTER-LAYER>]
                            [<SWITCH-LAYER>]
                            [<REQ-ADAP-CAP>]
         <of-list>::=<OF>[<of-list>]
         <metric-list>::=<METRIC>[<metric-list>]


6. Manageability Considerations

   TBD

   Manageability of inter-layer traffic engineering with PCE must
   address the following consideration for section 5.1.

   - need for a MIB module for control and monitoring
   - need for built-in diagnostic tools
   - configuration implication for the protocol

7. IANA Considerations

7.1. New PCEP Objects

   Three new objects: the INTER-LAYER object, the SWITCH-LAYER object,
   and the REQ-ADAP-CAP object.



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   INTER-LAYER Object-Class is to be assigned by IANA (recommended
   value=18)

   INTER-LAYER Object-Type is to be assigned by IANA (recommended
   value=1)

   SWITCH-LAYER Object-Class is to be assigned by IANA (recommended
   value=19)

   SWITCH-LAYER Object-Type is to be assigned by IANA (recommended
   value=1)

   REQ-ADAP-CAP Object-Class is to be assigned by IANA (recommended
   value=20)

   REQ-ADAP-CAP Object-Type is to be assigned by IANA (recommended
   value=1)

7.2. New Registry for INTER-LAYER Object Flags

   IANA is requested to create a registry to manage the Flag field of
   the INTER-Layer object.

   New bit numbers may be allocated only by an IETF Consensus action.
   Each bit should be tracked with the following qualities:

   o  Bit number (counting from bit 0 as the most significant bit)

   o  Capability Description

   o  Defining RFC

   Several bits are defined for the INTER-LAYER object flag fields in
   this document. The following values have been assigned:

   Bit Number   Description   Reference

    29            T flag        this document
    30            M flag        this document
    31            I flag        this document

7.3. METRIC Type

   Two new metric types are defined in this document for the METRIC
   object (specified in [RFC5440]). The IANA is requested to make the
   following allocation (suggested value):


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   - Type 11 : Number of adaptations on a path

   - Type 12 : Number of layers on a path

8. Security Considerations

   TBD

   Inter-layer traffic engineering with PCE may raise new security
   issues when PCE-PCE communication is done between different layer
   networks for inter-layer path computation. Security issues may also
   exist when a single PCE is granted full visibility of TE information
   that applies to multiple layers.

   It is expected that solutions for inter-layer protocol extensions
   will address these issues in detail using security techniques such as
   authentication.

9. Acknowledgments



10. References

10.1. Normative References

   [RFC2119] S. Bradner, "Key words for use in RFCs to indicate
             requirements levels", RFC 2119, March 1997.

   [RFC3471] L. Burger, "Generalized Multi-Protocol Label Switching
             (GMPLS)", RFC 3471, January 2003.

   [RFC3945] E. Mannie, "Generalized Multi-Protocol Label Switching
             Architecture", RFC 3945, October 2004.

   [RFC4203] K. Kompella and Y. Rekhter, "OSPF Extensions in Support of
             Generalized Multi-Protocol Label Switching (GMPLS)", RFC
             4203, October 2005.

   [RFC4206] K. Kompella, and Y. Rekhter, "Label Switched Paths (LSP)
             Hierarchy with Generalized Multi-Protocol Label Switching
             (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.

   [RFC5440] JP. Vasseur et al, "Path Computation Element (PCE)
             Communication Protocol (PCEP)" RFC 5440, March 2009.




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   [PCE-INTER-LAYER-REQ] E. Oki et al., "PCC-PCE Communication
             Requirements for Inter-Layer Traffic Engineering", draft-
             ietf-pce-inter-layer-req, work in progress.

   [RFC5623] E. Oki et al., "Framework for PCE-Based Inter-Layer MPLS
             and GMPLS Traffic Engineering", September 2009.

   RFC5339]  JL. Le Roux et al, "Evaluation of Existing GMPLS Protocols
             against Multi-Layer and Multi-Region Networks (MLN/MRN)",
             RFC5339, September 2008.

10.2. Informative References

   [RFC4655] A. Farrel, JP. Vasseur and J. Ash, "A Path Computation
             Element (PCE)-Based Architecture", RFC 4655, September 2006.

   [RFC5212] K. Shiomoto et al., "Requirements for GMPLS-based multi-
             region and multi-layer networks (MRN/MLN)", RFC 5212, July
             2008.

   [MLN-SOL] D. Papadimitriou et al., " Generalized Multi-Protocol Label
             Switching (GMPLS) Protocol Extensions for Multi-Layer and
             Multi-Region Networks (MLN/MRN)", draft-ietf-ccamp-gmpls-
             mln-extensions, work in progress.

   [RFC5150] A. Ayyangar et al., "Label Switched Path Stitching with
             Generalized Multiprotocol Label Switching Traffic
             Engineering (GMPLS TE)", RFC 5150, February 2008.

   [RFC5511] Farrel, A., "Reduced Backus-Naur Form (RBNF) A Syntax Used
             in Various Protocol Specifications", April 2009.



11. Authors' Addresses

   Eiji Oki
   University of Electro-Communications
   Tokyo
   Japan
   Email: oki@ice.uec.ac.jp


   Tomonori Takeda
   NTT



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   3-9-11 Midori-cho,
   Musashino-shi, Tokyo 180-8585, Japan
   Email: takeda.tomonori@lab.ntt.co.jp


   Jean-Louis Le Roux
   France Telecom R&D,
   Av Pierre Marzin,
   22300 Lannion, France
   Email: jeanlouis.leroux@orange-ftgroup.com


   Adrian Farrel
   Old Dog Consulting
   Email: adrian@olddog.co.uk

   Fatai Zhang
   Huawei Technologies Co., Ltd.
   F3-5-B R&D Center, Huawei Base,
   Bantian, Longgang District
   Shenzhen 518129 P.R.China
   Phone: +86-755-28972912
   Email: zhangfatai@huawei.com


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   repository at http://www.ietf.org/ipr



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