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Internet Engineering Task Force (IETF) D. Papadimitriou Request for Comments: 6001 M. Vigoureux Updates: 4202, 4203, 4206, 4874, 4974, 5307 Alcatel-Lucent Category: Standards Track K. Shiomoto ISSN: 2070-1721 NTT

                                                           D. Brungard
                                                                   ATT
                                                           JL. Le Roux
                                                        France Telecom
                                                          October 2010
            Generalized MPLS (GMPLS) Protocol Extensions
        for Multi-Layer and Multi-Region Networks (MLN/MRN)

Abstract

 There are specific requirements for the support of networks
 comprising Label Switching Routers (LSRs) participating in different
 data plane switching layers controlled by a single Generalized Multi-
 Protocol Label Switching (GMPLS) control plane instance, referred to
 as GMPLS Multi-Layer Networks / Multi-Region Networks (MLN/MRN).
 This document defines extensions to GMPLS routing and signaling
 protocols so as to support the operation of GMPLS Multi-Layer /
 Multi-Region Networks.  It covers the elements of a single GMPLS
 control plane instance controlling multiple Label Switched Path (LSP)
 regions or layers within a single Traffic Engineering (TE) domain.

Status of This Memo

 This is an Internet Standards Track document.
 This document is a product of the Internet Engineering Task Force
 (IETF).  It represents the consensus of the IETF community.  It has
 received public review and has been approved for publication by the
 Internet Engineering Steering Group (IESG).  Further information on
 Internet Standards is available in Section 2 of RFC 5741.
 Information about the current status of this document, any errata,
 and how to provide feedback on it may be obtained at
 http://www.rfc-editor.org/info/rfc6001.

Papadimitriou, et al. Standards Track [Page 1] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

Copyright Notice

 Copyright (c) 2010 IETF Trust and the persons identified as the
 document authors.  All rights reserved.
 This document is subject to BCP 78 and the IETF Trust's Legal
 Provisions Relating to IETF Documents
 (http://trustee.ietf.org/license-info) in effect on the date of
 publication of this document.  Please review these documents
 carefully, as they describe your rights and restrictions with respect
 to this document.  Code Components extracted from this document must
 include Simplified BSD License text as described in Section 4.e of
 the Trust Legal Provisions and are provided without warranty as
 described in the Simplified BSD License.
 This document may contain material from IETF Documents or IETF
 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
 the copyright in such materials, this document may not be modified
 outside the IETF Standards Process, and derivative works of it may
 not be created outside the IETF Standards Process, except to format
 it for publication as an RFC or to translate it into languages other
 than English.

Papadimitriou, et al. Standards Track [Page 2] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

Table of Contents

 1. Introduction ....................................................3
    1.1. Conventions Used in This Document ..........................4
 2. Summary of the Requirements and Evaluation ......................4
 3. Interface Adjustment Capability Descriptor (IACD) ...............5
    3.1. Overview ...................................................5
    3.2. Interface Adjustment Capability Descriptor (IACD) ..........6
 4. Multi-Region Signaling ..........................................9
    4.1. XRO Subobjects ............................................10
 5. Virtual TE Link ................................................12
    5.1. Edge-to-Edge Association ..................................13
    5.2. Soft Forwarding Adjacency (Soft FA) .......................16
 6. Backward Compatibility .........................................18
 7. Security Considerations ........................................18
 8. IANA Considerations ............................................18
    8.1. RSVP ......................................................18
    8.2. OSPF ......................................................20
    8.3. IS-IS .....................................................20
 9. References .....................................................20
    9.1. Normative References ......................................20
    9.2. Informative References ....................................22
 Acknowledgments....................................................23
 Contributors ......................................................23

1. Introduction

 Generalized Multi-Protocol Label Switching (GMPLS) [RFC3945] extends
 MPLS to handle multiple switching technologies: packet switching
 (PSC), Layer 2 switching (L2SC), Time-Division Multiplexing (TDM)
 Switching, wavelength switching (LSC) and fiber switching (FSC).  A
 GMPLS switching type (PSC, TDM, etc.) describes the ability of a node
 to forward data of a particular data plane technology, and uniquely
 identifies a control plane LSP region.  LSP regions are defined in
 [RFC4206].  A network comprised of multiple switching types (e.g.,
 PSC and TDM) controlled by a single GMPLS control plane instance is
 called a Multi-Region Network (MRN).
 A data plane layer is a collection of network resources capable of
 terminating and/or switching data traffic of a particular format.
 For example, LSC, TDM VC-11, and TDM VC-4-64c represent three
 different layers.  A network comprising transport nodes participating
 in different data plane switching layers controlled by a single GMPLS
 control plane instance is called a Multi-Layer Network (MLN).

Papadimitriou, et al. Standards Track [Page 3] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 The applicability of GMPLS to multiple switching technologies
 provides the unified control and operations for both LSP provisioning
 and recovery.  This document covers the elements of a single GMPLS
 control plane instance controlling multiple layers within a given TE
 domain.  A TE domain is defined as group of Label Switching Routers
 (LSRs) that enforces a common TE policy.  A Control Plane (CP)
 instance can serve one, two, or more layers.  Other possible
 approaches, such as having multiple CP instances serving disjoint
 sets of layers, are outside the scope of this document.
 The next sections provide the procedural aspects in terms of routing
 and signaling for such environments as well as the extensions
 required to instrument GMPLS to provide the capabilities for MLN/MRN
 unified control.  The rationales and requirements for Multi-
 Layer/Region networks are set forth in [RFC5212].  These requirements
 are evaluated against GMPLS protocols in [RFC5339] and several areas
 where GMPLS protocol extensions are required are identified.
 This document defines GMPLS routing and signaling extensions so as to
 cover GMPLS MLN/MRN requirements.

1.1. 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 [RFC2119].
 In addition, the reader is assumed to be familiar with [RFC3945],
 [RFC3471], [RFC4201], [RFC4202], [RFC4203], [RFC4206], and [RFC5307].

2. Summary of the Requirements and Evaluation

 As identified in [RFC5339], most MLN/MRN requirements rely on
 mechanisms and procedures (such as local procedures and policies, or
 specific TE mechanisms and algorithms) that are outside the scope of
 the GMPLS protocols, and thus do not require any GMPLS protocol
 extensions.
 Four areas for extensions of GMPLS protocols and procedures have been
 identified in [RFC5339]:
 o GMPLS routing extensions for the advertisement of the internal
   adjustment capability of hybrid nodes.  See Section 3.2.2 of
   [RFC5339].

Papadimitriou, et al. Standards Track [Page 4] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 o GMPLS signaling extensions for constrained multi-region signaling
   (Switching Capability inclusion/exclusion).  See Section 3.2.1 of
   [RFC5339].  An additional eXclude Route Object (XRO) Label
   subobject is also defined since it was absent from [RFC4874].
 o GMPLS signaling extensions for the setup/deletion of virtual TE
   links (as well as exact trigger for its actual provisioning).  See
   Section 3.1.1.2 of [RFC5339].
 o GMPLS routing and signaling extensions for graceful TE link
   deletion.  See Section 3.1.1.3 of [RFC5339].
 The first three requirements are addressed in Sections 3, 4, and 5 of
 this document, respectively.  The fourth requirement is addressed in
 [RFC5710] with additional context provided by [RFC5817].

3. Interface Adjustment Capability Descriptor (IACD)

 In the MRN context, nodes that have at least one interface that
 supports more than one switching capability are called hybrid nodes
 [RFC5212].  The logical composition of a hybrid node contains at
 least two distinct switching elements that are interconnected by
 "internal links" to provide adjustment between the supported
 switching capabilities.  These internal links have finite capacities
 that MUST be taken into account when computing the path of a multi-
 region TE-LSP.  The advertisement of the internal adjustment
 capability is required as it provides critical information when
 performing multi-region path computation.

3.1. Overview

 In an MRN environment, some LSRs could contain multiple switching
 capabilities, such as PSC and TDM or PSC and LSC, all under the
 control of a single GMPLS instance.
 These nodes, hosting multiple Interface Switching Capabilities (ISCs)
 [RFC4202], are required to hold and advertise resource information on
 link states and topology, just like other nodes (hosting a single
 ISC).  They may also have to consider some portions of internal node
 resources use to terminate hierarchical LSPs, since in circuit-
 switching technologies (such as TDM, LSC, and FSC) LSPs require the
 use of resources allocated in a discrete manner (as predetermined by
 the switching type).  For example, a node with PSC+LSC hierarchical
 switching capability can switch a lambda LSP, but cannot terminate
 the Lambda LSP if there is no available (i.e., not already in use)
 adjustment capability between the LSC and the PSC switching
 components.  Another example occurs when L2SC (Ethernet) switching
 can be adapted in the Link Access Procedure-SDH (LAPS) X.86 and

Papadimitriou, et al. Standards Track [Page 5] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 Generic Framing Procedure (GFP) for instance, before reaching the TDM
 switching matrix.  Similar circumstances can occur, for example, if a
 switching fabric that supports both PSC and L2SC functionalities is
 assembled with LSC interfaces enabling "lambda" encoding.  In the
 switching fabric, some interfaces can terminate Lambda LSPs and
 perform frame (or cell) switching whilst other interfaces can
 terminate Lambda LSPs and perform packet switching.
 Therefore, within multi-region networks, the advertisement of the so-
 called adjustment capability to terminate LSPs (not the interface
 capability since the latter can be inferred from the bandwidth
 available for each switching capability) provides the information to
 take into account when performing multi-region path computation.
 This concept enables a node to discriminate the remote nodes (and
 thus allows their selection during path computation) with respect to
 their adjustment capability, e.g., to terminate LSPs at the PSC or
 LSC level.
 Hence, we introduce the capability of discriminating the (internal)
 adjustment capability from the (interface) switching capability by
 defining an Interface Adjustment Capability Descriptor (IACD).
 A more detailed problem statement can be found in [RFC5339].

3.2. Interface Adjustment Capability Descriptor (IACD)

 The Interface Adjustment Capability Descriptor (IACD) provides the
 information for the forwarding/switching capability.
 Note that the addition of the IACD as a TE link attribute does not
 modify the format of the Interface Switching Capability Descriptor
 (ISCD) defined in [RFC4202], and does not change how the ISCD sub-TLV
 is carried in the routing protocols or how it is processed when it is
 received [RFC4201], [RFC4203].
 The receiving LSR uses its Link State Database to determine the
 IACD(s) of the far end of the link.  Different Interface Adjustment
 Capabilities at two ends of a TE link are allowed.

3.2.1. OSPF

 In OSPF, the IACD sub-TLV is defined as an optional sub-TLV of the TE
 Link TLV (Type 2, see [RFC3630]), with Type 25 and variable length.

Papadimitriou, et al. Standards Track [Page 6] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 The IACD sub-TLV format is defined 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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 | Lower SC      | Lower Encoding| Upper SC      | Upper Encoding|
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 0              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 1              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 2              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 3              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 4              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 5              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 6              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                  Max LSP Bandwidth at priority 7              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |            Adjustment Capability-specific information         |
 |                           (variable)                          |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Lower Switching Capability (SC) field (byte 1) - 8 bits
       Indicates the lower switching capability associated with the
       Lower Encoding field (byte 2).  The value of the Lower
       Switching Capability field MUST be set to the value of
       Switching Capability of the ISCD sub-TLV advertised for this TE
       link.  If multiple ISCD sub-TLVs are advertised for that TE
       link, the Lower Switching Capability (SC) value MUST be set to
       the value of SC to which the adjustment capacity is associated.
    Lower Encoding (byte 2) - 8 bits
       Contains one of the LSP Encoding Type values specified in
       Section 3.1.1 of [RFC3471] and updates.
    Upper Switching Capability (SC) field (byte 3) - 8 bits
       Indicates the upper switching capability.  The Upper Switching
       Capability field MUST be set to one of the values defined in
       [RFC4202].

Papadimitriou, et al. Standards Track [Page 7] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

    Upper Encoding (byte 4) - 8 bits
       Set to the encoding of the available adjustment capacity and to
       0xFF when the corresponding SC value has no access to the wire,
       i.e., there is no ISC sub-TLV for this upper switching
       capability.  The adjustment capacity is the set of resources
       associated to the upper switching capability.
    Max LSP Bandwidth
       The Maximum LSP Bandwidth is encoded as a list of eight 4-octet
       fields in the IEEE floating point format [IEEE], with priority
       0 first and priority 7 last.  The units are bytes per second.
       Processing MUST follow the rules specified in [RFC4202].
    The Adjustment Capability-specific information - variable
       This field is defined so as to leave the possibility for future
       addition of technology-specific information associated to the
       adjustment capability.
       Other fields MUST be processed as specified in [RFC4202] and
       [RFC4203].
 The bandwidth values provide an indication of the resources still
 available to perform insertion/extraction for a given adjustment at a
 given priority (resource pool concept: set of shareable available
 resources that can be assigned dynamically).
 Multiple IACD sub-TLVs MAY be present within a given TE Link TLV.
 The presence of the IACD sub-TLV as part of the TE Link TLV does not
 modify the format/messaging and the processing associated to the ISCD
 sub-TLV defined in [RFC4203].

3.2.2. IS-IS

 In IS-IS, the IACD sub-TLV is an optional sub-TLV of the Extended IS
 Reachability TLV (see [RFC5305]) with Type 27.
 The IACD sub-TLV format is identical to the OSPF sub-TLV format
 defined in Section 3.2.1.  The fields of the IACD sub-TLV have the
 same processing and interpretation rules as defined in Section 3.2.1.
 Multiple IACD sub-TLVs MAY be present within a given extended IS
 reachability TLV.

Papadimitriou, et al. Standards Track [Page 8] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 The presence of the IACD sub-TLV as part of the extended IS
 reachability TLV does not modify format/messaging and processing
 associated to the ISCD sub-TLV defined in [RFC5307].

4. Multi-Region Signaling

 Section 6.2 of [RFC4206] specifies that when a region boundary node
 receives a Path message, the node determines whether or not it is at
 the edge of an LSP region with respect to the Explicit Route Object
 (ERO) carried in the message.  If the node is at the edge of a
 region, it must then determine the other edge of the region with
 respect to the Explicit Route Object (ERO), using the IGP database.
 The node then extracts from the ERO the sub-sequence of hops from
 itself to the other end of the region.
 The node then compares the sub-sequence of hops with all existing
 Forwarding Agency LSPs (FA-LSPs) originated by the node:
 o If a match is found, that FA-LSP has enough unreserved bandwidth
   for the LSP being signaled, and the Generalized PID (G-PID) of the
   FA-LSP is compatible with the G-PID of the LSP being signaled, the
   node uses that FA-LSP as follows.  The Path message for the
   original LSP is sent to the egress of the FA-LSP.  The previous hop
   (PHOP) in the message is the address of the node at the head-end of
   the FA-LSP.  Before sending the Path message, the ERO in that
   message is adjusted by removing the subsequence of the ERO that
   lies in the FA-LSP, and replacing it with just the endpoint of the
   FA-LSP.
 o If no existing FA-LSP is found, the node sets up a new FA-LSP.
   That is, it initiates a new LSP setup just for the FA-LSP.
   Note: compatible G-PID implies that traffic can be processed by
   both ends of the FA-LSP without dropping traffic after its
   establishment.
 Applying the procedure of [RFC4206] in an MRN environment MAY lead to
 the setup of single-hop FA-LSPs between each pair of nodes.
 Therefore, considering that the path computation is able to take into
 account richness of information with regard to the SC available on
 given nodes belonging to the path, it is consistent to provide enough
 signaling information to indicate the SC to be used and over which
 link.  Particularly, in case a TE link has multiple SCs advertised as
 part of its ISCD sub-TLVs, an ERO does not provide a mechanism to
 select a particular SC.

Papadimitriou, et al. Standards Track [Page 9] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 In order to limit the modifications to existing RSVP-TE procedures
 ([RFC3473] and referenced), this document defines a new subobject of
 the eXclude Route Object (XRO), see [RFC4874], called the Switching
 Capability subobject.  This subobject enables (when desired) the
 explicit identification of at least one switching capability to be
 excluded from the resource selection process described above.
 Including this subobject as part of the XRO that explicitly indicates
 which SCs have to be excluded (before initiating the procedure
 described here above) over a specified TE link, solves the ambiguous
 choice among SCs that are potentially used along a given path and
 give the possibility to optimize resource usage on a multi-region
 basis.  Note that implicit SC inclusion is easily supported by
 explicitly excluding other SCs (e.g., to include LSC, it is required
 to exclude PSC, L2SC, TDM, and FSC).
 The approach followed here is to concentrate exclusions in XRO and
 inclusions in ERO.  Indeed, the ERO specifies the topological
 characteristics of the path to be signaled.  Usage of Explicit
 Exclusion Route Subobjects (EXRSs) would also lead in the exclusion
 over certain portions of the LSP during the FA-LSP setup.  Thus, it
 is more suited to extend generality of the elements excluded by the
 XRO but also prevent complex consistency checks as well as
 transpositions between EXRS and XRO at FA-LSP head-ends.

4.1. XRO Subobjects

 The contents of an EXCLUDE_ROUTE object defined in [RFC4874] are a
 series of variable-length data items called subobjects.
 This document defines the Switching Capability (SC) subobject of the
 XRO (Type 35), its encoding, and processing.  It also complements the
 subobjects defined in [RFC4874] with a Label subobject (Type 3).

4.1.1. SC Subobject

 XRO subobject Type 35: Switching Capability
  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=35   |    Length     |   Attribute   | Switching Cap |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    L (1 bit)
       0 indicates that the attribute specified MUST be excluded.

Papadimitriou, et al. Standards Track [Page 10] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

       1 indicates that the attribute specified SHOULD be avoided.
    Type (7 bits)
       The Type of the XRO SC subobject is 35.
    Length (8 bits)
       The total length of the subobject in bytes (including the Type
       and Length fields).  The Length of the XRO SC subobject is 4.
    Attribute (8 bits)
       0 reserved value.
       1 indicates that the specified SC SHOULD be excluded or avoided
         with respect to the preceding numbered (Type 1 or Type 2) or
         unnumbered interface (Type) subobject.
    Switching Cap (8 bits)
       Switching Capability value to be excluded.
 The Switching Capability subobject MUST follow the set of one or more
 numbered or unnumbered interface subobjects to which this subobject
 refers.
 In the case of a loose-hop ERO subobject, the XRO subobject MUST
 precede the loose-hop subobject identifying the tail-end
 node/interface of the traversed region(s).

4.1.2. Label Subobject

 The encoding of the XRO Label subobject is identical to the Label ERO
 subobject defined in [RFC3473] with the exception of the L bit.  The
 XRO Label subobject is defined as follows:
 XRO Subobject Type 3: Label Subobject
  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=3     |    Length     |U|   Reserved  |   C-Type      |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                             Label                             |
 |                              ...                              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

Papadimitriou, et al. Standards Track [Page 11] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

    L (1 bit)
       0 indicates that the attribute specified MUST be excluded.
       1 indicates that the attribute specified SHOULD be avoided.
    Type (7 bits)
       The Type of the XRO Label subobject is 3.
    Length (8 bits)
       The total length of the subobject in bytes (including the Type
       and Length fields).  The Length is always divisible by 4.
    U (1 bit)
       See [RFC3471].
    C-Type (8 bits)
       The C-Type of the included Label Object.  Copied from the Label
       Object (see [RFC3471]).
    Label
       See [RFC3471].
 XRO Label subobjects MUST follow the numbered or unnumbered interface
 subobjects to which they refer, and, when present, MUST also follow
 the Switching Capability subobject.
 When XRO Label subobjects are following the Switching Capability
 subobject, the corresponding label values MUST be compatible with the
 SC capability to be explicitly excluded.

5. Virtual TE Link

 A virtual TE link is defined as a TE link between two upper-layer
 nodes that is not associated with a fully provisioned FA-LSP in a
 lower layer [RFC5212].  A virtual TE link is advertised as any TE
 link, following the rules in [RFC4206] defined for fully provisioned
 TE links.  A virtual TE link represents thus the potentiality to set
 up an FA-LSP in the lower layer to support the TE link that has been
 advertised.  In particular, the flooding scope of a virtual TE link
 is within an IGP area, as is the case for any TE link.

Papadimitriou, et al. Standards Track [Page 12] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 Two techniques can be used for the setup, operation, and maintenance
 of virtual TE links.  The corresponding GMPLS protocols extensions
 are described in this section.  The procedures described in this
 section complement those defined in [RFC4206] and [HIER-BIS].

5.1. Edge-to-Edge Association

 This approach, that does not require state maintenance on transit
 LSRs, relies on extensions to the GMPLS RSVP-TE Call procedure (see
 [RFC4974]).  This technique consists of exchanging identification and
 TE attributes information directly between TE link endpoints through
 the establishment of a call between terminating LSRs.  These TE link
 endpoints correspond to the LSP head-end and tail-end points of the
 LSPs that will be established.  The endpoints MUST belong to the same
 (LSP) region.
 Once the call is established, the resulting association populates the
 local Traffic Engineering DataBase (TEDB) and the resulting virtual
 TE link is advertised as any other TE link.  The latter can then be
 used to attract traffic.  When an upper-layer/region LSP tries to
 make use of this virtual TE link, one or more FA LSPs MUST be
 established using the procedures defined in [RFC4206] to make the
 virtual TE link "real" and allow it to carry traffic by nesting the
 upper-layer/region LSP.
 In order to distinguish usage of such call from the call and
 associated procedures defined in [RFC4974], a CALL_ATTRIBUTES object
 is introduced.

5.1.1. CALL_ATTRIBUTES Object

 The CALL_ATTRIBUTES object is used to signal attributes required in
 support of a call, or to indicate the nature or use of a call.  It is
 modeled on the LSP_ATTRIBUTES object defined in [RFC5420].  The
 CALL_ATTRIBUTES object MAY also be used to report call operational
 state on a Notify message.
 The CALL_ATTRIBUTES object class is 202 of the form 11bbbbbb.  This
 C-Num value (see [RFC2205], Section 3.10) ensures that LSRs that do
 not recognize the object pass it on transparently.
 One C-Type is defined, C-Type = 1 for Call Attributes.  This object
 is OPTIONAL and MAY be placed on Notify messages to convey additional
 information about the desired attributes of the call.

Papadimitriou, et al. Standards Track [Page 13] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 CALL_ATTRIBUTES class = 202, C-Type = 1
  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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 //                      Call Attributes TLVs                   //
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 The Call Attributes TLVs are encoded as described in Section 5.1.3.

5.1.2. Processing

 If an egress (or intermediate) LSR does not support the object, it
 forwards it unexamined and unchanged.  This facilitates the exchange
 of attributes across legacy networks that do not support this new
 object.

5.1.3. Call Attributes TLVs

 Attributes carried by the CALL_ATTRIBUTES object are encoded within
 TLVs named Call Attributes TLVs.  One or more Call Attributes TLVs
 MAY be present in each object.
 There are no ordering rules for Call Attributes TLVs, and no
 interpretation SHOULD be placed on the order in which these TLVs are
 received.
 Each Call Attributes TLV carried by the CALL_ATTRIBUTES object is
 encoded 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
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |             Type              |           Length              |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
 |                                                               |
 //                            Value                            //
 |                                                               |
 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    Type
       The identifier of the TLV.

Papadimitriou, et al. Standards Track [Page 14] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

    Length
       Indicates the total length of the TLV in octets.  That is, the
       combined length of the Type, Length, and Value fields, i.e.,
       four plus the length of the Value field in octets.
       The entire TLV MUST be padded with between zero and three
       trailing zeros to make it four-octet aligned.  The Length field
       does not count any padding.
    Value
       The data field for the TLV padded as described above.
 Assignment of Call Attributes TLV types MUST follow the rules
 specified in Section 8 (IANA Considerations).

5.1.4. Call Attributes Flags TLV

 The Call Attributes TLV of Type 1 defines the Call Attributes Flags
 TLV.  The Call Attributes Flags TLV MAY be present in a
 CALL_ATTRIBUTES object.
 The Call Attributes Flags TLV value field is an array of units of 32
 flags numbered from the most significant bit as bit zero.  The Length
 field for this TLV MUST therefore always be a multiple of 4 bytes,
 regardless of the number of bits carried and no padding is required.
 Unassigned bits are considered reserved and MUST be set to zero on
 transmission by the originator of the object.  Bits not contained in
 the Call Attributes Flags TLV MUST be assumed to be set to zero.  If
 the Call Attributes Flags TLV is absent, either because it is not
 contained in the CALL_ATTRIBUTES object or because this object is
 itself absent, all processing MUST be performed as though the bits
 were present and set to zero.  In other terms, assigned bits that are
 not present either because the Call Attributes Flags TLV is
 deliberately foreshortened or because the TLV is not included MUST be
 treated as though they are present and are set to zero.

5.1.5. Call Inheritance Flag

 This document introduces a specific Call Inheritance Flag at position
 bit 0 (most significant bit) in the Call Attributes Flags TLV.  This
 flag indicates that the association initiated between the endpoints
 belonging to a call results into a (virtual) TE link advertisement.

Papadimitriou, et al. Standards Track [Page 15] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 The Call Inheritance Flag MUST be set to 1 in order to indicate that
 the established association is to be translated into a TE link
 advertisement.  The value of this flag SHALL by default be set to 1.
 Setting this flag to 0 results in a hidden TE link or in deleting the
 corresponding TE link advertisement (by setting the corresponding
 Opaque LSA Age to MaxAge) if the association had been established
 with this flag set to 1.  In the latter case, the corresponding FA-
 LSP SHOULD also be torn down to prevent unused resources.
 The Notify message used for establishing the association is defined
 as per [RFC4974].  Additionally, the Notify message MUST carry an
 LSP_TUNNEL_INTERFACE_ID Object, that allows identifying unnumbered
 FA-LSPs ([RFC3477], [RFC4206], [HIER-BIS]) and numbered FA-LSPs
 ([RFC4206], [HIER-BIS]).

5.2. Soft Forwarding Adjacency (Soft FA)

 The Soft Forwarding Adjacency (Soft FA) approach consists of setting
 up the FA LSP at the control plane level without actually committing
 resources in the data plane.  This means that the corresponding LSP
 exists only in the control plane domain.  Once such an FA is
 established, the corresponding TE link can be advertised following
 the procedures described in [RFC4206].
 There are two techniques to set up Soft FAs:
 o The first one consists in setting up the FA LSP by precluding
   resource commitment during its establishment.  These are known as
   pre-planned LSPs.
 o The second technique consists in making use of path-provisioned
   LSPs only.  In this case, there is no associated resource demand
   during the LSP establishment.  This can be considered as the RSVP-
   TE equivalent of the Null service type specified in [RFC2997].

5.2.1. Pre-Planned LSP Flag

 The LSP ATTRIBUTES object and Attributes Flags TLV are defined in
 [RFC5420].  The present document defines a new flag, the Pre-Planned
 LSP flag, in the existing Attributes Flags TLV (numbered as Type 1).
 The position of this flag is bit 6 in accordance with IANA
 assignment.  This flag, part of the Attributes Flags TLV, follows
 general processing of [RFC5420] for LSP_REQUIRED_ATTRIBUTE object.
 That is, LSRs that do not recognize the object reject the LSP setup
 effectively saying that they do not support the attributes requested.
 Indeed, the newly defined attribute requires examination at all
 transit LSRs along the LSP being established.

Papadimitriou, et al. Standards Track [Page 16] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 The Pre-Planned LSP flag can take one of the following values:
 o When set to 0, this means that the LSP MUST be fully provisioned.
   Absence of this flag (hence corresponding TLV) is therefore
   compliant with the signaling message processing per [RFC3473]).
 o When set to 1, this means that the LSP MUST be provisioned in the
   control plane only.
 If an LSP is established with the Pre-Planned flag set to 1, no
 resources are committed at the data plane level.
 The operation of committing data plane resources occurs by re-
 signaling the same LSP with the Pre-Planned flag set to 0.  It is
 RECOMMENDED that no other modifications are made to other RSVP
 objects during this operation.  That is each intermediate node,
 processing a flag transiting from 1 to 0 shall only be concerned with
 the commitment of data plane resources and no other modification of
 the LSP properties and/or attributes.
 If an LSP is established with the Pre-Planned flag set to 0, it MAY
 be re-signaled by setting the flag to 1.

5.2.2. Path Provisioned LSPs

 There is a difference between an LSP that is established with 0
 bandwidth (path provisioning) and an LSP that is established with a
 certain bandwidth value not committed at the data plane level (i.e.,
 pre-planned LSP).
 Mechanisms for provisioning (pre-planned or not) LSP with 0 bandwidth
 is straightforward for PSC LSP: in the SENDER_TSPEC/FLOWSPEC object,
 the Peak Data Rate field of IntServ objects (see [RFC2210]) MUST be
 set to 0.  For L2SC LSP: the Committed Information Rate (CIR), Excess
 Information Rate (EIR), Committed Burst Size (CBS), and Excess Burst
 Size (EBS) values MUST be set to 0 in the Type 2 sub-TLV of the
 Ethernet Bandwidth Profile TLV.  In both cases, upon LSP resource
 commitment, actual traffic parameter values are used to perform
 corresponding resource reservation.
 However, mechanisms for provisioning (pre-planned or not) a TDM or
 LSC LSP with 0 bandwidth is currently not possible because the
 exchanged label value is tightly coupled with resource allocation
 during LSP signaling (e.g., see [RFC4606] for a SONET/SDH LSP).  For
 TDM and LSC LSP, a NULL Label value is used to prevent resource
 allocation at the data plane level.  In these cases, upon LSP
 resource commitment, actual label value exchange is performed to
 commit allocation of timeslots/ wavelengths.

Papadimitriou, et al. Standards Track [Page 17] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

6. Backward Compatibility

 New objects and procedures defined in this document are running
 within a given TE domain, defined as group of LSRs that enforces a
 common TE policy.  Thus, the extensions defined in this document are
 expected to run in the context of a consistent TE policy.
 Specification of a consistent TE policy is outside the scope of this
 document.
 In such TE domains, we distinguish between edge LSRs and intermediate
 LSRs.  Edge LSRs MUST be able to process Call Attributes as defined
 in Section 5.1 if this is the method selected for creating edge-to-
 edge associations.  In that domain, intermediate LSRs are by
 definition transparent to the Call processing.
 In case the Soft FA method is used for the creation of virtual TE
 links, edge and intermediate LSRs MUST support processing of the LSP
 ATTRIBUTE object per Section 5.2.

7. Security Considerations

 This document does not introduce any new security considerations from
 the ones already detailed in [RFC5920] that describes the MPLS and
 GMPLS security threats, the related defensive techniques, and the
 mechanisms for detection and reporting.  Indeed, the applicability of
 the proposed GMPLS extensions is limited to single TE domain.  Such a
 domain is under the authority of a single administrative entity.  In
 this context, multiple switching layers comprised within such TE
 domain are under the control of a single GMPLS control plane
 instance.
 Nevertheless, Call initiation, as depicted in Section 5.1, MUST
 strictly remain under control of the TE domain administrator.  To
 prevent any abuse of Call setup, edge nodes MUST ensure isolation of
 their call controller (i.e., the latter is not reachable via external
 TE domains).  To further prevent man-in-the-middle attacks, security
 associations MUST be established between edge nodes initiating and
 terminating calls.  For this purpose, Internet Key Exchange (IKE)
 protocol [RFC5996] MUST be used for performing mutual authentication
 and establishing and maintaining these security associations.

8. IANA Considerations

8.1. RSVP

 IANA has made the following assignments in the "Class Names, Class
 Numbers, and Class Types" section of the "RSVP PARAMETERS" registry
 available from http://www.iana.org.

Papadimitriou, et al. Standards Track [Page 18] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 This document introduces a new class named CALL_ATTRIBUTES, which has
 been created in the 11bbbbbb range with the following definition:
 Class Number  Class Name                         Reference
 ------------  -----------------------            ---------
 202           CALL ATTRIBUTES                    [RFC6001]
               Class Type (C-Type):
               1   Call Attributes                [RFC6001]
 IANA has established a "Call Attributes TLV" registry.  The following
 types are defined:
 TLV Value  Name                                  Reference
 ---------  -------------------------             ---------
 0          Reserved                              [RFC6001]
 1          Call Attributes Flags TLV             [RFC6001]
 The values should be allocated based on the following allocation
 policy as defined in [RFC5226].
 Range         Registration Procedures
 -----         ------------------------
 0-32767       RFC Required
 32768-65535   Reserved for Private Use
 IANA has established a "Call Attributes Flags" registry.  The
 following flags are defined:
 Bit Number  32-bit Value  Name                   Reference
 ----------  ------------  ---------------------  ---------
 0           0x80000000    Call Inheritance Flag  [RFC6001]
 The values should be allocated based on the "RFC Required" policy as
 defined in [RFC5226].
 This document introduces a new Flag in the Attributes Flags TLV
 defined in [RFC5420]:
 Bit Number  Name                   Reference
 ----------  --------------------   ---------
 6           Pre-Planned LSP Flag   [RFC6001]
 This document introduces two new subobjects for the EXCLUDE_ROUTE
 object [RFC4874], C-Type 1.

Papadimitriou, et al. Standards Track [Page 19] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 Subobject Type   Subobject Description
 --------------   -------------------------
 3                Label
 35               Switching Capability (SC)

8.2. OSPF

 IANA maintains the "Open Shortest Path First (OSPF) Traffic
 Engineering TLVs" registries including the "Types for sub-TLVs of TE
 link TLV (Value 2)" registry.
 This document defines the following sub-TLV of TE link TLV (Value 2).
 Value  Sub-TLV
 -----  -------------------------------------------------
 25     Interface Adjustment Capability Descriptor (IACD)

8.3. IS-IS

 This document defines the following new sub-TLV type of top-level TLV
 22 that has been reflected in the ISIS sub-TLV registry for TLV 22,
 141, and 222:
 Type  Description                                        Length
 ----  -------------------------------------------------  ------
 27    Interface Adjustment Capability Descriptor (IACD)  Var.

9. References

9.1. Normative References

 [IEEE]     IEEE, "IEEE Standard for Binary Floating-Point
            Arithmetic", Standard 754-1985, 1985.
 [RFC2205]  Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S.
            Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1
            Functional Specification", RFC 2205, September 1997.
 [RFC2210]  Wroclawski, J., "The Use of RSVP with IETF Integrated
            Services", RFC 2210, September 1997.
 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC2997]  Bernet, Y., Smith, A., and B. Davie, "Specification of the
            Null Service Type", RFC 2997, November 2000.

Papadimitriou, et al. Standards Track [Page 20] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 [RFC3471]  Berger, L., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Signaling Functional Description", RFC
            3471, January 2003.
 [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Signaling Resource ReserVation Protocol-
            Traffic Engineering (RSVP-TE) Extensions", RFC 3473,
            January 2003.
 [RFC3477]  Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links
            in Resource ReSerVation Protocol - Traffic Engineering
            (RSVP-TE)", RFC 3477, January 2003.
 [RFC3630]  Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
            (TE) Extensions to OSPF Version 2", RFC 3630, September
            2003.
 [RFC3945]  Mannie, E., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Architecture", RFC 3945, October 2004.
 [RFC4201]  Kompella, K., Rekhter, Y., and L. Berger, "Link Bundling
            in MPLS Traffic Engineering (TE)", RFC 4201, October 2005.
 [RFC4202]  Kompella, K., Ed., and Y. Rekhter, Ed., "Routing
            Extensions in Support of Generalized Multi-Protocol Label
            Switching (GMPLS)", RFC 4202, October 2005.
 [RFC4203]  Kompella, K., Ed., and Y. Rekhter, Ed., "OSPF Extensions
            in Support of Generalized Multi-Protocol Label Switching
            (GMPLS)", RFC 4203, October 2005.
 [RFC4206]  Kompella, K. and Y. Rekhter, "Label Switched Paths (LSP)
            Hierarchy with Generalized Multi-Protocol Label Switching
            (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.
 [RFC4606]  Mannie, E. and D. Papadimitriou, "Generalized Multi-
            Protocol Label Switching (GMPLS) Extensions for
            Synchronous Optical Network (SONET) and Synchronous
            Digital Hierarchy (SDH) Control", RFC 4606, August 2006.
 [RFC4874]  Lee, CY., Farrel, A., and S. De Cnodder, "Exclude Routes -
            Extension to Resource ReserVation Protocol-Traffic
            Engineering (RSVP-TE)", RFC 4874, April 2007.

Papadimitriou, et al. Standards Track [Page 21] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 [RFC4974]  Papadimitriou, D. and A. Farrel, "Generalized MPLS (GMPLS)
            RSVP-TE Signaling Extensions in Support of Calls", RFC
            4974, August 2007.
 [RFC5226]  Narten, T. and H. Alvestrand, "Guidelines for Writing an
            IANA Considerations Section in RFCs", BCP 26, RFC 5226,
            May 2008.
 [RFC5305]  Li, T. and H. Smit, "IS-IS Extensions for Traffic
            Engineering", RFC 5305, October 2008.
 [RFC5307]  Kompella, K., Ed., and Y. Rekhter, Ed., "IS-IS Extensions
            in Support of Generalized Multi-Protocol Label Switching
            (GMPLS)", RFC 5307, October 2008.
 [RFC5420]  Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A.
            Ayyangarps, "Encoding of Attributes for MPLS LSP
            Establishment Using Resource Reservation Protocol Traffic
            Engineering (RSVP-TE)", RFC 5420, February 2009.
 [RFC5996]  Kaufman, C., Hoffman, P., Nir, Y., and P. Eronen,
            "Internet Key Exchange Protocol Version 2 (IKEv2)", RFC
            5996, September 2010.

9.2. Informative References

 [HIER-BIS] Shiomoto, K., Ed., and A. Farrel, "Procedures for
            Dynamically Signaled Hierarchical Label Switched Paths",
            Work in Progress, February 2010.
 [RFC5212]  Shiomoto, K., Papadimitriou, D., Le Roux, JL., Vigoureux,
            M., and D. Brungard, "Requirements for GMPLS-Based Multi-
            Region and Multi-Layer Networks (MRN/MLN)", RFC 5212, July
            2008.
 [RFC5339]  Le Roux, JL., Ed., and D. Papadimitriou, Ed., "Evaluation
            of Existing GMPLS Protocols against Multi-Layer and Multi-
            Region Networks (MLN/MRN)", RFC 5339, September 2008.
 [RFC5710]  Berger, L., Papadimitriou, D., and JP. Vasseur, "PathErr
            Message Triggered MPLS and GMPLS LSP Reroutes", RFC 5710,
            January 2010.
 [RFC5817]  Ali, Z., Vasseur, JP., Zamfir, A., and J. Newton,
            "Graceful Shutdown in MPLS and Generalized MPLS Traffic
            Engineering Networks", RFC 5817, April 2010.

Papadimitriou, et al. Standards Track [Page 22] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

 [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
            Networks", RFC 5920, July 2010.

Acknowledgments

 The authors would like to thank Mr. Wataru Imajuku for the
 discussions on adjustment between regions.

Contributors

 Eiji Oki
 University of Electro-Communications
 1-5-1 Chofugaoka
 Chofu, Tokyo 182-8585, Japan
 EMail: oki@ice.uec.ac.jp
 Ichiro Inoue
 NTT Network Service Systems Laboratories
 3-9-11 Midori-cho
 Musashino-shi, Tokyo 180-8585, Japan
 Phone: +81 422 596076
 EMail: ichiro.inoue@lab.ntt.co.jp
 Emmanuel Dotaro
 Alcatel-Lucent France
 Route de Villejust
 91620 Nozay, France
 Phone: +33 1 69634723
 EMail: emmanuel.dotaro@alcatel-lucent.fr
 Gert Grammel
 Alcatel-Lucent SEL
 Lorenzstrasse, 10
 70435 Stuttgart, Germany
 EMail: gert.grammel@alcatel-lucent.de

Papadimitriou, et al. Standards Track [Page 23] RFC 6001 GMPLS Protocol Extensions for MLN/MRN October 2010

Authors' Addresses

 Dimitri Papadimitriou
 Alcatel-Lucent
 Copernicuslaan 50
 B-2018 Antwerpen, Belgium
 Phone: +32 3 2408491
 EMail: dimitri.papadimitriou@alcatel-lucent.com
 Martin Vigoureux
 Alcatel-Lucent
 Route de Villejust
 91620 Nozay, France
 Phone: +33 1 30772669
 EMail: martin.vigoureux@alcatel-lucent.fr
 Kohei Shiomoto
 NTT
 3-9-11 Midori-cho
 Musashino-shi, Tokyo 180-8585, Japan
 Phone: +81 422 594402
 EMail: shiomoto.kohei@lab.ntt.co.jp
 Deborah Brungard
 ATT
 Rm. D1-3C22 - 200 S. Laurel Ave.
 Middletown, NJ 07748, USA
 Phone: +1 732 4201573
 EMail: dbrungard@att.com
 Jean-Louis Le Roux
 France Telecom
 Avenue Pierre Marzin
 22300 Lannion, France
 Phone: +33 2 96053020
 EMail: jean-louis.leroux@rd.francetelecom.com

Papadimitriou, et al. Standards Track [Page 24]

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