Network Working Group                      J.L. Le Roux (France Telecom)
Internet Draft                                        D. Brungard (AT&T)
Category: Informational                                     E. Oki (NTT)
Expires: January April 2007                          D.  Papadimitriou (Alcatel)
                                                       K. Shiomoto (NTT)
                                                  M. Vigoureux (Alcatel)

                                                            October 2006

        Evaluation of existing GMPLS Protocols against Multi Layer
                    and Multi Region Networks (MLN/MRN)

               draft-ietf-ccamp-gmpls-mln-eval-01.txt

               draft-ietf-ccamp-gmpls-mln-eval-02.txt

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Abstract

   This document provides an evaluation of Generalized Multi-Protocol
   Label Switching (GMPLS) protocols and mechanisms against the
   requirements for Multi-Layer Networks (MLN) and Multi-Region Networks
   (MRN). In addition, this document identifies areas where additional
   protocol extensions or procedures are needed to satisfy these
   requirements, and provides guidelines for potential extensions.

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.

Table of Contents

   1.      Terminology.................................................3
   2.      Introduction................................................3
   3.      MLN/MRN Requirements Overview...............................4
   4.      Analysis....................................................5      Analysis....................................................4
   4.1.    Multi-Layer Aspects.........................................5 Aspects.........................................4
   4.1.1.  Support for Virtual Network Topology Reconfiguration........5 Reconfiguration........4
   4.1.1.1.  Control of FA-LSPs Setup/Release..........................5
   4.1.1.2.  Virtual TE-Links..........................................7 TE-Links..........................................6
   4.1.1.3.  Traffic Disruption Minimization During FA Release.........8
   4.1.1.4.  Stability.................................................8
   4.1.2.  Support for FA-LSP Attributes Inheritance...................8
   4.1.3.  Support for Triggered Signaling.............................9 Signaling.............................8
   4.1.4.  FA Connectivity Verification................................9
   4.2.    Multi-Region Specific Aspects...............................9
   4.2.1.  Support for Multi-Region Signaling..........................9
   4.2.2.  Advertisement of Internal Adaptation Capabilities..........10
   4.3.    Client and server network aspects..........................12
   4.3.1.  Administrative boundary....................................12
   4.3.2.  Path computation across separated TEDs.....................12
   4.3.3.  Association between TE-links in separated TEDs.............12
   5.      Evaluation Conclusion......................................12
   6.      Security Considerations....................................13
   7.      Acknowledgments............................................13
   8.      References.................................................13
   8.1.    Normative..................................................13
   8.2.    Informative................................................14    Informative................................................13
   9.      Authors' Addresses:........................................14
   10.     Intellectual Property Statement............................15

1. Terminology

   This document uses terminologies defined in [RFC3945], [HIER], [RFC4206], and
   [MLN-REQ].

2. Introduction

   Generalized Multi-Protocol Label Switching (GMPLS) extends MPLS to
   handle multiple switching technologies: packet switching (PSC),
   layer-two switching (L2SC), TDM switching (TDM), wavelength switching
   (LSC) and fiber switching (FSC) (see [RFC 3945]).

   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 with different data
   plane switching layers controlled either by a single GMPLS control plane
   instance is called a Multi-Layer Network (MLN).

   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 region. The notion of LSP Region
   is defined in [HIER]. [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).

   Note that the region is a control plane only concept. That is, layers
   of the same region share the same switching technology and,
   therefore, need the same set of technology specific signaling
   objects.

   Note that a MRN is necessarily a MLN, but not vice versa, as a MLN
   may consist of a single region (control of multiple data plane layers
   within a region). Hence, in the following, we use the term layer if
   the mechanism discussed applies equally to layers and regions (e.g.
   VNT, virtual TE-link, etc.), and we specifically use the term region
   if the mechanism applies only for supporting a MRN.

   A customer network may be provided on top of a server GMPLS-based
   MRN/MLN which is operated by a service provider. For example, a pure
   IP and/or an IP/MPLS network can be provided on top of GMPLS-based
   packet over optical networks [IW-MIG-FW]. The relationship between
   the networks is a client/server relationship and such services are
   referred to as "MRN/MLN services". In this case, the customer network
   may form part of the MRN/MLN, or may be partially separated, for
   example to maintain separate routing information but retain common
   signalling.

   The objectives of this document are to evaluate existing GMPLS
   mechanisms and protocols ([RFC 3945], [GMPLS-RTG], [GMPLS-SIG]) [RFC4202], [RFC3471]) against
   the requirements for MLN and MRN, defined in [MLN-REQ]. From this
   evaluation, we identify several areas where additional protocol
   extensions and modifications are required to meet these requirements,
   and provide guidelines for potential extensions.

   Section 3 provides an

   An overview of MLN/MRN requirements.
   Section requirements is provided in section 3. Then
   section 4 evaluates for each of these requirements, whether current
   GMPLS protocols and mechanisms allow addressing the requirements.
   When the requirements are not met, the document identifies whether
   the required mechanisms could rely on GMPLS protocols and procedure
   extensions or if it is entirely out of the scope of GMPLS protocols.

   Note that this document specifically addresses GMPLS control plane
   functionality for MLN/MRN in the context of a single administrative
   control plane partition.

3. MLN/MRN Requirements Overview

   [MLN-REQ] lists a set of functional requirements for Multi
   Layer/Region Networks (MLN/MRN). These requirements are summarized
   below:

        - Support of robust Virtual Network Topology (VNT)
          reconfiguration. This implies the following requirements:
                - Optimal control of FA-LSP setup and release;
                - Support for virtual TE-links;
                - Traffic Disruption minimization during FA-LSP release
                  (e.g. network reconfiguration events);
                - Stability Stability;

        - Support for FA-LSP attributes inheritance;

        - Support for Triggered Signaling;

        - Support for FA FA-LSP data plane connectivity verification;

        - Support for Multi-region Multi-Region signaling;

        - Advertisement of the adaptation capabilities and resources;

   Interconnection of MLN/MRN (server) networks with administratively
   separated client networks introduces as set of specific requirements:

        - Support for administrative boundary between client and server
          MLN/MRN network , minimizing impact on the customer network
          design, operation, and administration;

        - Support for path computation across separated TEDs associated
          with client and server MLN/MRN network;

        - Support for association between TE-links in separated TEDs
          associated with client and server MLN/MRN networks;

4. Analysis

4.1. Multi-Layer Aspects

4.1.1. Support for Virtual Network Topology Reconfiguration

   A set of lower-layer FA-LSPs provides a Virtual Network Topology
   (VNT) to the upper-layer. By reconfiguring the VNT (FA-LSP
   setup/release) according to traffic demands between source and
   destination node pairs of a layer, network performance factors such
   as maximum link utilization and residual capacity of the network can
   be optimized. Such optimal VNT reconfiguration implies several
   mechanisms that are analyzed in the following sections.

   Note that the VNT approach is just one approach among others, to
   perform inter-layer Traffic Engineering.

4.1.1.1. Control of FA-LSPs Setup/Release

   In a Multi-Layer Network, FA-LSPs are created, modified, released
   periodically according to the change of incoming traffic demands from
   the upper layer.

   This implies a TE mechanism that takes into account the demands
   matrix, the TE topology and potentially the current VNT, in order to
   compute a new VNT.

   Several functional building blocks are required to support such TE
   mechanism:

        - Discovery of TE topology and available resources; resources.

        - Collection of traffic demands of the upper layer; layer.

        - VNT resources policing/scheduling with regards to traffic
          demands and usage (i.e. decision to setup/release FAs); The
          functional component in charge of this function is called a
          VNT Manager (VNTM), it may be distributed on network
          elements or centralized on an external tool (see [VNTM]). It
          may also be partially centralized and distributed; distributed.

        - VNT Path Computation according to TE topology, and potentially
          taking into account old VNT (to minimize changes); The
          Functional component in charge of VNT computation may be
          distributed on network elements or may be centralized on an
          external tool (such as e.g. a PCE); PCE).

        - FA-LSP setup/release.

   GMPLS routing protocols support TE topology discovery and discovery. GMPLS
   signaling protocols allow setting up/releasing FA-LSPs.

   VNT Management functions (resources policing/scheduling, decision to
   setup/release FA, FA configuration) are out of the scope of GMPLS
   protocols. Such functionalities can be achieved directly on layer
   border LSRs, and/or on one or more external tools. When an external
   tool is used, an interface is required between the VNTM and network
   elements so has to setup/releases FA-LSPs. This may rely on SNMP (TE
   MIB) or on proprietary interfaces.

   The set of traffic demands of the upper layer is required for the VNT
   Manager to take decisions to setup/release FAs. This requires
   knowledge of the aggregated bandwidth reserved by upper layer LSPs
   established between any pair of border LSRs.
   Existing GMPLS routing allows for the collection of traffic demands
   of the upper region. It can be deduced from FA TE-link advertisements.
   The set of traffic demands can be inferred:
      - either directly, based on upper-layer FA TE-link advertisements.

        The traffic demands between two points correspond to the
        cumulated bandwidth reserved by upper-layer LSPs between these
        two points;
      - or indirectly, based on lower-layer FA TE-link advertisements.
        In this case a mechanism to infer the upper-layer traffic demand
        from the aggregated bandwidth reserved in lower-layer LSPs might
        be required, as all pairs of border nodes may not be directly
        connected by a lower layer LSP.

   Collection of traffic demands of an upper region may actually be
   achieved in several ways depending on the location of VNT Managers:
      - If a VNTM is distributed on border layer LSRs, then the
        collection of traffic demands would rely on existing GMPLS
        routing, as per described above;
      - If a VNTM is centralized on an external tool, then the
        collection of traffic demands may be achieved using existing
        GMPLS routing, provided that the tool relies on GMPLS routing to
        discover TE link information, or it may rely on another
        mechanism out of the scope of GMPLS protocols (e.g. SNMP TE-link
        MIB).

   Finally, VNT computation can be performed directly on layer border
   LSRs or on an external tool (such as an external PCE) and this
   independently of the location of the VNTM. VNT computation is
   triggered by the VNTM (e.g. when the Path computation is externalized
   on a PCE, the VNTM acts as PCC).

   Hence no GMPLS protocol extensions are required to control FA-LSP
   setup/release.

4.1.1.2. Virtual TE-Links

   A Virtual TE-link is a TE-link between two nodes, not actually
   associated to a fully provisioned FA-LSP. A Virtual TE-link
   represents the potentiality to setup a FA-LSP. There is no IGP
   adjacency associated to a Virtual TE-link. A Virtual TE-link is
   advertised as any classical TE-link, i.e. following the rules in
   [HIER]
   [RFC4206] defined for fully provisioned TE-links. Particularly, the
   flooding scope of a Virtual TE-link is within an IGP area, as any TE-
   link.

   During its signalling, if an upper-layer LSP makes use of a Virtual
   TE-link, the underlying FA-LSP is immediately signalled and
   provisioned.

   The use of Virtual TE-links has two main advantages:

     - flexibility: allows to compute a LSP path using TE-links and this
       without taking into account the actual status of the
       corresponding FA-LSP in the lower layer in terms of provisioning;
     - stability: allows stability of TE-links, TE-links in the upper layer, while
       avoiding wastage of bandwidth in the lower layer, as data plane
       connections are not established.

   Virtual TE-links are setup/deleted/modified dynamically, according to
   the change of the (forecast) traffic demand, operator's policies for
   capacity utilization, and the available resources in the lower layer.

   The support of Virtual TE-links requires two main building blocks:
        - A TE mechanism for dynamic modification of Virtual TE-link
          Topology;
        - A signalling mechanism for the dynamic setup and deletion of
          virtual TE-links. Setting up a virtual TE-link requires a
          signalling mechanism allowing an end-to-end association
          between Virtual TE-link end points so as to exchange link
          identifiers as well as some TE parameters.

   The TE mechanism responsible for triggering/policing dynamic
   modification of Virtual TE-links is out of the scope of GMPLS
   protocols.

   Current GMPLS signaling signalling does not allow setting up and releasing
   Virtual TE-links. Hence GMPLS signaling signalling must be extended to support
   Virtual TE-links.

   We can distinguish two options for setting up Virtual TE-links:

        - The Soft FA approach, that consists of setting up the FA-LSP
   in the control plane without actually activating cross connections in
   the data plane. One the one hand, this requires state maintenance on
   all transit LSRs (N square issue), but on the other hand this may
   allow for some admission control. Indeed, when a soft-FA is
   activated, there may be no longer available resources for other soft-
   FAs that were sharing common links, these soft-FA will be dynamically
   released and corresponding virtual TE-links are deleted. The soft-FA
   LSPs may be setup using procedures similar to those described in
   [GMPLS-RECOVERY] for setting up secondary LSPs.

        -The remote association approach, that simply consists of
   exchanging virtual TE-links ids and parameters directly between TE-
   link end points. This does not require state maintenance on transit
   LSRs, but reduce admission control capabilities. Such an association
   between Virtual TE-link end-points may rely on extensions to the
   RSVP-TE ASON Call procedure ([GMPLS-ASON]). ([ASON-CALL]).

   Note that the support of Virtual TE-link does not require any GMPLS
   routing extension.

4.1.1.3. Traffic Disruption Minimization During FA Release

   Before deleting a given FA-LSP, all nested LSPs have to be rerouted
   and removed from the FA-LSP to avoid traffic disruption.
   The mechanisms required here are similar to those required for
   graceful deletion of a TE-Link. A Graceful TE-link deletion mechanism
   allows for the deletion of a TE-link without disrupting traffic of
   TE-LSPs that where using the TE-link.
   GMPLS protocols do not provide for explicit indication to trigger
   such operation.

   Hence, GMPLS routing and/or signaling extensions are required
   to support graceful deletion of TE-links.  This may rely, for
   instance, on new signaling Error code to notify head-end LSRs that a
   TE-link along the path of a LSP is going to disappear, and also on
   new routing attributes (if limited to a single IGP area), such as
   defined in [GR-SHUT].

4.1.1.4. Stability

   The upper-layer LSP stability may be impaired if the VNT undergoes
   frequent changes. In this context robustness of the VNT is defined as
   the capability to smooth impact of these changes and avoid their
   subsequent propagation.

   Guaranteeing VNT stability is out of the scope of GMPLS protocols and
   relies entirely on the capability of TE algorithms to minimize
   routing perturbations. This requires that the TE algorithm takes into
   account the old VNT when computing a new VNT, and tries to minimize
   the perturbation.

4.1.2. Support for FA-LSP Attributes Inheritance

   When FA TE-link parameters are inherited from FA-LSP parameters,
   specific inheritance rules are applied.

   This relies on local procedures and policies and is out of the scope
   of GMPLS protocols.
   Note that this requires that both head-end and tail-end of the FA-LSP
   are driven by same policies.

4.1.3. Support for Triggered Signaling.

   When a LSP crosses the boundary from an upper to a lower layer, it
   may be nested in or stitched to a lower-layer LSP. If such an LSP
   does not exist the LSP may be established dynamically. Such a
   mechanism is referred to as "Triggered signaling".

   Triggered signaling requires the following building blocks:
        - The identification of layer boundaries.
        - A path computation engine capable of computing a path
          containing multiple layers.

        - A mechanism for nested signaling.

   The identification of layer boundaries is supported by GMPLS routing
   protocols. The identification of layer boundaries is performed using
   the interface switching capability descriptor associated to the TE-
   link (see [HIER] [RFC4206] and [GMPLS-RTG]). [RFC4202]).

   The capability to compute a path containing multiple layers is a
   local implementation issue and is out of the scope of GMPLS protocols.

   A mechanism for nested signaling is defined in [HIER]. [RFC4206].

   Hence, GMPLS protocols already meet this requirement.

4.1.4. FA Connectivity Verification

   Once fully provisioned, FA liveliness may be achieved by verifying
   its data plane connectivity.

   FA connectivity verification relies on technology specific mechanisms
   (e.g. for SDH, G.707, G.783, for MPLS, BFD, etc.) as for any other
   LSP. Hence this requirement is out of the scope of GMPLS protocols.

   Note that the time to establish the FA-LSP must be minimized.

4.2. Multi-Region Specific Aspects

4.2.1. Support for Multi-Region Signaling

   Applying the triggered signaling procedure discussed above, in a MRN
   environment may lead to the setup of one-hop FA-LSPs between each
   node. Therefore, considering that the path computation is able to
   take into account richness of information with regard to the
   Switching Capability (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 on over which link.

   Limited extension to existing GMPLS signaling procedures is required
   for this purpose as it only mandates indication of the SCs to be
   included or excluded before initiating the LSP provisioning procedure.
   This enhancement would solve the ambiguous choice of SC that are
   potentially used along a given path, particularly in case of ERO
   expansion, or when an ERO sub-object identifies a multi-SC TE-link.
   This would give the possibility to optimize resource usage on a
   multi-region basis.

4.2.2. Advertisement of Internal Adaptation Capabilities

   In the MRN context, nodes supporting more than one switching
   capability on at least one interface are called Hybrid nodes. Hybrid
   nodes contain at least two distinct switching elements that are
   interconnected by internal links to provide adaptation between the
   supported switching capabilities. These internal links have finite
   capacities and must be taken into account when computing the path of
   a multi-region TE-LSP. The advertisement of the internal adaptation
   capability is required as it provides critical information when
   performing multi-region path computation.

   Figure 1a below shows an example of hybrid node. The hybrid node has
   two switching elements (matrices), which support here TDM and PSC
   switching respectively. The node terminates two PSC and TDM ports
   (port1 and port2 respectively). It also has internal link connecting
   the two switching elements.
   The two switching elements are internally interconnected in such a
   way that it is possible to terminate some of the resources of the TDM
   port 2 and provide through them adaptation for PSC traffic,
   received/sent over the internal PSC interface (#b). Two ways are
   possible to set up PSC LSPs (port 1 or port 2). Available resources
   advertisement e.g. Unreserved and Min/Max LSP Bandwidth should cover
   both ways.

                             Network element
                        .............................
                        :            --------       :
              PSC       :           |  PSC   |      :
            Port1-------------<->--|#a      |      :
                        :  +--<->---|#b      |      :
                        :  |         --------       :
              TDM       :  |        ----------      :
              +PSC      :  +--<->--|#c  TDM   |     :
            Port2 ------------<->--|#d        |     :
                        :           ----------      :
                        :............................

                             Figure 1a. Hybrid node.

   Port 1 and Port 2 can be grouped together thanks to internal DWDM, to
   result in a single interface: Link 1. This is illustrated in figure
   1b below.

                             Network element
                        .............................
                        :            --------       :
                        :           |  PSC   |      :
                        :           |        |      :
                        :         --|#a      |      :
                        :        |  |   #b   |      :
                        :        |   --------       :
                        :        |       |          :
                        :        |  ----------      :
                        :    /|  | |    #c    |     :
                        :   | |--  |          |     :
              Link1 ========| |    |    TDM   |     :
                        :   | |----|#d        |     :
                        :    \|     ----------      :
                        :............................

                        Figure 1b. Hybrid node.

   Let's assume that all interfaces are STM16 (with VC4-16c capable
   as Max LSP bandwidth). After, setting up several PSC LSPs via port #a
   and setting up and terminating several TDM LSPs via port #d and port
   #b, there is only 155 Mb capacities still available on port #b.
   However a 622 Mb capacity remains on port #a and VC4-5c capacity on
   port #d.

   When computing the path for a new VC4-4c TDM LSP, one must know, that
   this node cannot terminate this LSP, as there is only 155Mb still
   available for TDM-PSC adaptation. Hence the internal TDM-PSC
   adaptation capability must be advertised.

   With current GMPLS routing [GMPLS-RTG] [RFC4202] this advertisement is possible
   if link bundling is not used and if two TE-links are advertised for
   link1:

   We would have the following TE-link advertisements:

   TE-link 1 (port 1):
        - ISCD sub-TLV: PSC with Max LSP bandwidth = 622Mb, unreserved
                        bandwidth = 622Mb.

   TE-Link 2 (port 2):
        - ISCD #1 sub-TLV: TDM with Max LSP bandwidth = VC4-4c,
                           unreserved bandwidth = vc4-5c.
        - ISCD #2 sub-TLV: PSC with Max LSP bandwidth = 155 Mb,
                           unreserved bandwidth = 155 Mb.

   The ISCD 2 in TE-link 2 represents actually the internal TDM-PSC
   adaptation capability.

   However if for obvious scalability reasons link bundling is done then
   the adaptation capability information is lost with current GMPLS
   routing, as we have the following TE-link advertisement:

   TE-link 1 (port 1 + port 2):
        - ISCD #1 sub-TLV: TDM with Max LSP bandwidth = VC4-4c,
                           unreserved bandwidth = vc4-5c.
        - ISCD #2 sub-TLV: PSC with Max LSP bandwidth = 622 Mb,
                           unreserved bandwidth = 777 Mb.

   With such TE-link advertisement an element computing the path of a
   VC4-4C
   VC4-4c LSP cannot know that this LSP cannot be terminated on the
   node.

   Thus current GMPLS routing can support the advertisement of the
   internal adaptation capability but this precludes performing link
   bundling and thus faces significant scalability limitations.

   Hence, GMPLS routing must be extended to meet this requirement. This
   could rely on the advertisement of the internal adaptation
   capabilitiy capability
   as a new TE link attribute (that would complement the Interface
   Switching Capability Descriptor TE-link attribute).

4.3. Client and server network aspects

4.3.1. Administrative boundary

   TBD

4.3.2. Path computation across separated TEDs

   TBD

4.3.3. Association between TE-links in separated TEDs

   TBD

5. Evaluation Conclusion

   Most of the required MLN/MRN requirements functions will rely on mechanisms and
   procedures that are out of the scope of the GMPLS protocols, and thus
   do not require any GMPLS protocol extensions. They will rely on local
   procedures and policies, and on specific TE mechanisms and
   algorithms.

   As regards Virtual Network Topology (VNT) computation and
   reconfiguration, specific TE mechanisms that could for instance rely
   on PCE based mechanisms and protocols, need to be defined, but these
   mechanisms are out of the scope of GMPLS protocols.

   Four areas for extensions of GMPLS protocols and procedures have been
   identified:

        - GMPLS signalling extension for the setup/deletion of
          the virtual TE-links (as well as exact trigger for its actual
          provisioning);

        - GMPLS routing and signalling extension for graceful TE-link
          deletion;

        - GMPLS signalling extension for constrained multi-region
          signalling (SC inclusion/exclusion);

        - GMPLS routing extension for the advertisement of the
          internal adaptation capability of hybrid nodes.

6. Security Considerations

   This document specifically addresses GMPLS control plane
   functionality for MLN/MRN in the context of a single administrative
   control plane partition and hence does not introduce additional
   security threats beyond those described in [RFC3945].

7. Acknowledgments

   We would like to thank Julien Meuric and Igor Bryskin for their
   useful comments.

8. References

8.1. Normative

   [RFC3979] Bradner, S., "Intellectual Property Rights in IETF
   Technology", BCP 79, RFC 3979, March 2005.

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

   [GMPLS-RTG]

   [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing
   Extensions in Support of Generalized Multi-Protocol Label Switching",
   draft-ietf-ccamp-gmpls-routing, RFC4202, October 2005.

   [GMPLS-SIG]

   [RFC3471] Berger, L., et. al. "Generalized Multi-Protocol Label
   Switching (GMPLS) Signaling Functional Description", RFC 3471,
   January 2003.

8.2. Informative

   [GMPLS-ASON]

   [ASON-CALL] Papadimitriou, D., Farrel, A., et. al., " Generalized "Generalized MPLS
   (GMPLS) RSVP-TE Signaling Extensions in support of Automatically Switched Optical
   Network (ASON)", draft-ietf-ccamp-gmpls-rsvp-te-ason, Calls", draft-
   ietf-ccamp-gmpls-rsvp-te-call, work in progess. progress.

   [MLN-REQ] Shiomoto, K., Papadimitriou, D., Le Roux, J.L., Vigoureux,
   M., Brungard, D., "Requirements for GMPLS-based multi-region and
   multi-layer networks", draft-ietf-ccamp-gmpls-mrn-reqs, work in
   progess.

   [HIER]

   [RFC4206] K. Kompella and Y. Rekhter, "LSP hierarchy with generalized
   MPLS TE", draft-ietf-mpls-lsp-hierarchy, FRC4206, RFC4206, October 2005.

   [GR-SHUT] Ali, Z., Zamfir, A., "Graceful Shutdown in MPLS Traffic
   Engineering Network", draft-ali-ccamp-mpls-graceful-shutdown, draft-ietf-ccamp-mpls-graceful-shutdown, work
   in progress.

   [GMPLS-RECOVERY] Lang, Rekhter, Papadimitriou, "RSVP-TE Extensions in
   support of End-to-End Generalized Multi-Protocol Label Switching
   (GMPLS)-based Recovery", draft-ietf-ccamp-gmpls-recovery-e2e-
   signaling, work in progress.

   [VNTM] Oki, Le Roux, Farrel, "Definition of Virtual Network
   Topology Manager (VNTM) for PCE-based Inter-Layer MPLS and GMPLS
   Traffic Engineering", draft-oki-pce-vntm-def, work in progress.

   [IW-MIG-FMWK] Shiomoto, K et al., "Framework for IP/MPLS-GMPLS
   interworking in support of IP/MPLS to GMPLS migration", draft-ietf-
   ccamp-mpls-gmpls-interwork-fmwk, work in progress.

9. Authors' Addresses:

   Jean-Louis Le Roux (Editor)
   France Telecom
   2, avenue Pierre-Marzin
   22307 Lannion Cedex, France
   Email: jeanlouis.leroux@francetelecom.com jeanlouis.leroux@orange-ft.com

   Deborah Brungard
   AT&T
   Rm. D1-3C22 - 200 S. Laurel Ave.
   Middletown, NJ, 07748 USA
   E-mail: dbrungard@att.com

   Eiji Oki
   NTT
   3-9-11 Midori-Cho
   Musashino, Tokyo 180-8585, Japan
   Email: oki.eiji@lab.ntt.co.jp

   Dimitri Papadimitriou
   Alcatel
   Francis Wellensplein 1,
   B-2018 Antwerpen, Belgium
   Email: dimitri.papadimitriou@alcatel.be

   Kohei Shiomoto
   NTT
   3-9-11 Midori-Cho
   Musashino, Tokyo 180-8585, Japan
   Email: shiomoto.kohei@lab.ntt.co.jp
   Martin Vigoureux
   Alcatel
   Route de Nozay,
   91461 Marcoussis Cedex, France
   Email: martin.vigoureux@alcatel.fr

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