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Versions: (draft-shiomoto-ccamp-mpls-gmpls-interwork-fmwk) 00 01 02 03 04 05 RFC 5145

     Network Working Group                            Kohei Shiomoto(Editor)
     Internet Draft                                                    (NTT)
     Proposed Category: Informational
     Expires: February 2008
                                                                 August 2007
     
                      Framework for MPLS-TE to GMPLS migration
                  draft-ietf-ccamp-mpls-gmpls-interwork-fmwk-03.txt
     
     
     Status of this Memo
     
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     Abstract
     
        The migration from Multiprotocol Label Switching (MPLS) Traffic
        Engineering (TE) to Generalized MPLS (GMPLS) is the process of
        evolving an MPLS-TE control plane to a GMPLS control plane. An
        appropriate migration strategy will be selected based on various
        factors including the service provider's network deployment plan,
        customer demand, and operational policy.
     
        This document presents several migration models and strategies for
        migrating from MPLS-TE to GMPLS. In the course of migration, MPLS-TE
        and GMPLS devices, or networks, may coexist which may require
        interworking between MPLS-TE and GMPLS protocols. Aspects of the
        interworking required are discussed as it will influence the choice
        of a migration strategy. This framework document provides a migration
        toolkit to aid the operator in selection of an appropriate strategy.
     
     
     
     

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        This framework document also lists a set of solutions that may aid in
        interworking, and highlights a set of potential issues.
     
     Table of Contents
     
        1. Introduction...................................................2
        2. Conventions Used in This Document..............................3
        3. Motivations for Migration......................................4
        4. MPLS to GMPLS Migration Models.................................4
           4.1. Island model..............................................5
              4.1.1. Balanced Islands.....................................6
              4.1.2. Unbalanced Islands...................................6
           4.2. Integrated model..........................................7
           4.3. Phased model..............................................8
        5. Migration Strategies and Toolkit...............................8
           5.1. Migration Toolkit.........................................9
              5.1.1. Layered Networks.....................................9
              5.1.2. Routing Interworking................................11
              5.1.3. Signaling Interworking..............................12
        6. Manageability Considerations..................................13
           6.1. Control of Function and Policy...........................13
           6.2. Information and Data Models..............................14
           6.3. Liveness Detection and Monitoring........................14
           6.4. Verifying Correct Operation..............................14
           6.5. Requirements on Other Protocols and Functional Components14
           6.6. Impact on Network Operation..............................15
           6.7. Other Considerations.....................................15
        7. Security Considerations.......................................15
        8. IANA Considerations...........................................16
        9. Acknowledgements..............................................16
        10. Editor's Addresses...........................................17
        11. Authors' Addresses...........................................17
        12. References...................................................18
           12.1. Normative References....................................18
           12.2. Informative References..................................19
        13. Full Copyright Statement.....................................19
        14. Intellectual Property........................................20
     
     
     1. Introduction
     
        Multiprotocol Label Switching Traffic Engineering (MPLS-TE) to
        Generalized MPLS (GMPLS) migration is the process of evolving an
        MPLS-TE-based control plane to a GMPLS-based control plane. The
        network under consideration for migration is, therefore, a packet-
        switching network.
     
     
     
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        There are several motivations for such migration, mainly the desire
        to take advantage of new features and functions added to the GMPLS
        protocols and which are not present in MPLS-TE for packet networks.
        Additionally, before migrating a packet-switching network from MPLS-
        TE to GMPLS, one may choose to first migrate a lower-layer network
        with no control plane (e.g. controlled by a management plane) to
        using a GMPLS control plane, and this may lead to the desire for
        MPLS-TE/GMPLS (transport network) interworking to provide enhanced TE
        support and facilitate the later migration of the packet-switching
        network.
     
        Although an appropriate migration strategy will be selected based on
        various factors including the service provider's network deployment
        plan, customer demand, deployed network equipments, operational
        policy, etc., the transition mechanisms used should also provide
        consistent operation of newly introduced GMPLS networks, while
        minimizing the impact on the operation of existing MPLS-TE networks.
     
        This document describes several migration strategies and the
        interworking scenarios that arise during migration. It also examines
        the implications for network deployments and for protocol usage. As
        the GMPLS signaling and routing protocols are different from the
        MPLS-TE control protocols, interworking mechanisms between MPLS-TE
        and GMPLS networks, or network elements, may be needed to compensate
        for the differences.
     
        Note that MPLS-TE and GMPLS protocols can co-exist as "ships in the
        night" without any interworking issue.
     
     2. Conventions Used in This Document
     
        This is not a requirements document, nevertheless 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] in order to
        clarify the recommendations that are made.
     
        In the rest of this document, the term "GMPLS" includes both packet
        switching capable (PSC) and non-PSC. Otherwise the term "PSC GMPLS"
        or "non-PSC GMPLS" is explicitly used.
     
        In general, the term "MPLS" is used to indicate MPLS traffic
        engineering (MPLS-TE) only ([RFC3209], [RFC3630], [RFC3784]) and
        excludes other MPLS protocols such as the Label Distribution Protocol
        (LDP). TE functionalities of MPLS could be migrated to GMPLS, but
        non-TE functionalities could not. If non-TE MPLS is intended, it is
        explicitly indicated.
     
     
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        The reader is assumed to be familiar with the terminology introduced
        in [RFC3945].
     
     3. Motivations for Migration
     
        Motivations for migration will vary for different service providers.
        This section is presented to provide background so that the migration
        discussions may be seen in context. Sections 4 and 5 provide examples
        to illustrate the migration models and processes.
     
        Migration of an MPLS-capable LSR to include GMPLS capabilities may be
        performed for one or more reasons, including, not exhaustively:
     
        o  To add all GMPLS PSC features to an existing MPLS network (upgrade
           MPLS LSRs).
     
        o  To add specific GMPLS PSC features and operate them within an MPLS
           network (ex. [RFC4872] [RFC4873]).
     
        o  To integrate a new GMPLS PSC network with an existing MPLS network
           (without upgrading any of the MPLS LSRs).
     
        o  To allow existing MPLS LSRs to interoperate with new non-MPLS LSRs
           supporting only GMPLS PSC and/or non-PSC features.
     
        o  To integrate multiple control networks, e.g. managed by separate
           administrative organizations, and which independently utilize MPLS
           or GMPLS.
     
        o  To build integrated PSC and non-PSC networks. The non-PSC networks
           are controlled by GMPLS.
     
        The objective of migration from MPLS to GMPLS is that all LSRs, and
        the entire network, support GMPLS protocols. During this process,
        various interim situations may exist, giving rise to the interworking
        situations described in this document. The interim situations may
        exist for considerable periods of time, but the ultimate objective is
        not to preserve these situations. For the purposes of this document,
        they should be considered as temporary and transitory.
     
     4. MPLS to GMPLS Migration Models
     
        Three reference migration models are described below. Multiple
        migration models may co-exist in the same network.
     
     
     
     
     
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     4.1. Island model
     
        In the island model, "islands" of network nodes operating one
        protocol exist within a "sea" of nodes using the other protocol.
     
        For example, consider an island of GMPLS-capable nodes (PSC) which is
        introduced into a legacy MPLS network. Such an island might be
        composed of newly added GMPLS nodes, or might arise from the upgrade
        of existing nodes that previously operated MPLS protocols.
     
        The opposite is also quite possible. That is, there is a possibility
        that an island happens to be MPLS-capable within a GMPLS sea. Such a
        situation might arise in the later stages of migration, when all but
        a few islands of MPLS-capable nodes have been upgraded to GMPLS.
     
        It is also possible that a lower-layer, manually-provisioned network
        (for example, a TDM network) is constructed under an MPLS PSC network.
        During the process of migrating both networks to GMPLS, the lower-
        layer network might be migrated first. This would appear as a GMPLS
        island within an MPLS sea.
     
        Lastly, it is possible to consider individual nodes as islands. That
        is, it would be possible to upgrade or insert an individual GMPLS-
        capable node within an MPLS network, and to treat that GMPLS node as
        an island.
     
        Over time, collections of MPLS devices are replaced or upgraded to
        create new GMPLS islands or to extend existing ones, and distinct
        GMPLS islands may be joined together until the whole network is
        GMPLS-capable.
     
        From a migration/interworking point of view, we need to examine how
        these islands are positioned and how LSPs connect between the islands.
     
        Four categories of interworking scenarios are considered: (1) MPLS-
        GMPLS-MPLS, (2) GMPLS-MPLS-GMPLS, (3) MPLS-GMPLS and (4) GMPLS-MPLS.
        In case 1, the interworking behavior is examined based on whether the
        GMPLS islands are PSC or non-PSC.
     
        Figure 1 shows an example of the island model for MPLS-GMPLS-MPLS
        interworking. The model consists of a transit GMPLS island in an MPLS
        sea. The nodes at the boundary of the GMPLS island (G1, G2, G5, and
        G6) are referred to as "island border nodes". If the GMPLS island was
        non-PSC, all nodes except the island border nodes in the GMPLS-based
        transit island (G3 and G4) would be non-PSC devices, i.e., optical
        equipment (TDM, LSC, and FSC).
     
     
     
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        .................  ..........................  ..................
        :      MPLS      :  :          GMPLS         :  :     MPLS       :
        :+---+  +---+   +----+         +---+        +----+   +---+  +---+:
        :|R1 |__|R11|___| G1 |_________|G3 |________| G5 |___|R31|__|R3 |:
        :+---+  +---+   +----+         +-+-+        +----+   +---+  +---+:
        :      ________/ :  :  _______/  |   _____ / :  :  ________/     :
        :     /          :  : /          |  /        :  : /              :
        :+---+  +---+   +----+         +-+-+        +----+   +---+  +---+:
        :|R2 |__|R21|___| G2 |_________|G4 |________| G6 |___|R41|__|R4 |:
        :+---+  +---+   +----+         +---+        +----+   +---+  +---+:
        :................:  :........................:  :................:
     
           |<-------------------------------------------------------->|
                                       e2e LSP
     
     
        Figure 1 Example of the island model for MPLS-GMPLS-MPLS interworking.
     
     4.1.1. Balanced Islands
     
        In the MPLS-GMPLS-MPLS and GMPLS-MPLS-GMPLS cases, LSPs start and end
        using the same protocols. Possible strategies include:
     
        - tunneling the signaling across the island network using LSP
          nesting or stitching [STITCH] (the latter is for only with GMPLS-
          PSC)
     
        - protocol interworking or mapping (both are for only with GMPLS-
          PSC)
     
     4.1.2. Unbalanced Islands
     
        As previously discussed, there are two island interworking models
        which support bordering islands. GMPLS(PSC)-MPLS and MPLS-GMPLS(PSC)
        island cases are likely to arise where the migration strategy is not
        based on a core infrastructure, but has edge nodes (ingress or
        egress) located in islands of different capabilities.
     
        In this case, an LSP starts or ends in a GMPLS (PSC) island and
        correspondingly ends or starts in an MPLS island. This mode of
        operation can only be addressed using protocol interworking or
        mapping. Figure 2 shows the reference model for this migration
        scenario. Head-end and tail-end LSR are in distinct control plane
        clouds.
     
     
     
     
     
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             ............................  .............................
             :            MPLS          :  :       GMPLS (PSC)         :
             :+---+        +---+       +----+        +---+        +---+:
             :|R1 |________|R11|_______| G1 |________|G3 |________|G5 |:
             :+---+        +---+       +----+        +-+-+        +---+:
             :      ______/  |   _____/ :  :  ______/  |   ______/     :
             :     /         |  /       :  : /         |  /            :
             :+---+        +---+       +----+        +-+-+        +---+:
             :|R2 |________|R21|_______| G2 |________|G4 |________|G6 |:
             :+---+        +---+       +----+        +---+        +---+:
             :..........................:  :...........................:
     
               |<-------------------------------------------------->|
                                       e2e LSP
     
     
                       Figure 2 GMPLS-MPLS interworking model.
     
        It is important to underline that this scenario is also impacted by
        the directionality of the LSP, and the direction in which the LSP is
        established.
     
     4.2. Integrated model
     
        The second migration model involves a more integrated migration
        strategy. New devices that are capable of operating both MPLS and
        GMPLS protocols are introduced into the MPLS network.
     
        In the integrated model there are two types of nodes present during
        migration:
     
           - support MPLS only (legacy nodes)
     
           - support MPLS and GMPLS.
     
        In this model, as existing MPLS devices are upgraded to support both
        MPLS and GMPLS, the network continues to operate with a MPLS control
        plane, but some LSRs are also capable of operating with a GMPLS
        control plane. So, LSPs are provisioned using MPLS protocols where
        one end point of a service is a legacy MPLS node and/or where the
        selected path between end points traverses a legacy node that is not
        GMPLS-capable. But where the service can be provided using only
        GMPLS-capable nodes [TE-NODE-CAPS], it may be routed accordingly and
        can achieve a higher level of functionality by utilizing GMPLS
        features.
     
     
     
     
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        Once all devices in the network are GMPLS-capable, the MPLS specific
        protocol elements may be turned off, and no new devices need to
        support these protocol elements.
     
        In this model, the questions to be addressed concern the co-existence
        of the two protocol sets within the network. Actual interworking is
        not a concern.
     
     4.3. Phased model
     
        The phased model introduces GMPLS features and protocol elements into
        an MPLS network one by one. For example, some objects or sub-objects
        (such as the ERO label sub-object, [RFC3473]) might be introduced
        into the signaling used by LSRs that are otherwise MPLS-capable. This
        would produce a kind of hybrid LSR.
     
        This approach may appear simpler to implement as one is able to
        quickly and easily pick up key new functions without needing to
        upgrade the whole protocol implementation. It is most likely to be
        used where there is a desire to rapidly implement a particular
        function within a network without the necessity to install and test
        the full GMPLS function.
     
        Interoperability concerns though are exacerbated by this migration
        model, unless all LSRs in the network are updated simultaneously and
        there is a clear understanding of which subset of features are to be
        included in the hybrid LSRs. Interworking between a hybrid LSR and an
        unchanged MPLS LSR would put the hybrid LSR in the role of a GMPLS
        LSR as described in the previous sections and puts the unchanged LSR
        in the role of an MPLS LSR. The potential for different hybrids
        within the network will complicate matters considerably.
     
     5. Migration Strategies and Toolkit
     
        An appropriate migration strategy is selected by a network operator
        based on factors including the service provider's network deployment
        plan, customer demand, existing network equipment, operational policy,
        support from its vendors, etc.
     
        For PSC networks, the migration strategy involves the selection
        between the models described in the previous section. The choice will
        depend upon the final objective (full GMPLS capability, partial
        upgrade to include specific GMPLS features, or no change to existing
        IP/MPLS networks), and upon the immediate objectives (full, phased,
        or staged upgrade).
     
     
     
     
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        For PSC networks serviced by non-PSC networks, two basic migration
        strategies can be considered. In the first strategy, the non-PSC
        network is made GMPLS-capable, first, and then the PSC network is
        migrated to GMPLS. This might arise when, in order to expand the
        network capacity, GMPLS-based non-PSC sub-networks are introduced
        into the legacy MPLS-based networks. Subsequently, the legacy MPLS-
        based PSC network is migrated to be GMPLS-capable as described in the
        previous paragraph. Finally the entire network, including both PSC
        and non-PSC nodes, may be controlled by GMPLS.
     
        The second strategy for PSC and non-PSC networks is to migrate from
        the PSC network to GMPLS, first, and then enable GMPLS within the
        non-PSC network. The PSC network is migrated as described before, and
        when the entire PSC network is completely converted to GMPLS, GMPLS-
        based non-PSC devices and networks may be introduced without any
        issues of interworking between MPLS and GMPLS.
     
        These migration strategies and the migration models described in the
        previous section are not necessarily mutually exclusive. Mixtures of
        all strategies and models could be applied. The migration models and
        strategies selected will give rise to one or more of the interworking
        cases described in the following section.
     
     5.1. Migration Toolkit
     
        As described in the previous sections, an essential part of a
        migration and deployment strategy is how the MPLS and GMPLS or hybrid
        LSRs interwork. This section sets out some of the alternatives for
        achieving interworking between MPLS and GMPLS, and identifies some of
        the issues that need to be addressed. This document does not describe
        solutions to these issues.
     
        Note that it is possible to consider upgrading the routing and
        signaling capabilities of LSRs from MPLS to GMPLS separately.
     
     5.1.1. Layered Networks
     
        In the balanced island model, LSP tunnels [RFC4206] are a solution to
        carry the end-to-end LSPs across islands of incompatible nodes.
        Network layering is often used to separate domains of different data
        plane technology. It can also be used to separate domains of
        different control plane technology (such as MPLS and GMPLS protocols),
        and the solutions developed for multiple data plane technologies can
        be usefully applied to this situation [RFC3945], [RFC4206], and
        [RFC4726]. [MLN-REQ] gives a discussion of the requirements for
        multi-layered networks.
     
     
     
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        The GMPLS architecture [RFC3945] identifies three architectural
        models for supporting multi-layer GMPLS networks, and these models
        may be applied to the separation of MPLS and GMPLS control plane
        islands.
     
        - In the peer model, both MPLS and GMPLS nodes run the same routing
          instance, and routing advertisements from within islands of one
          level of protocol support are distributed to the whole network.
          This is achievable only as described in section 5.1.2 either by
          direct distribution or by mapping of parameters.
     
          Signaling in the peer model may result in contiguous LSPs,
          stitched LSPs [STITCH] (only for GMPLS PSC), or nested LSPs. If
          the network islands are non-PSC then the techniques of [MLN-REQ]
          may be applied, and these techniques may be extrapolated to
          networks where all nodes are PSC, but where there is a difference
          in signaling protocols.
     
        - The overlay model preserves strict separation of routing
          information between network layers. This is suitable for the
          balanced island model and there is no requirement to handle
          routing interworking. Even though the overlay model preserves
          separation of signaling information between network layers, there
          may be some interaction in signaling between network layers.
     
          The overlay model requires the establishment of control plane
          connectivity for the higher layer across the lower layer.
     
        - The augmented model allows limited routing exchange from the lower
          layer network to the higher layer network. Generally speaking,
          this assumes that the border nodes provide some form of filtering,
          mapping or aggregation of routing information advertised from the
          lower layer network. This architectural model can also be used for
          balanced island model migrations. Signaling interworking is
          required as described for the peer model.
     
        - The border peer architecture model is defined in [MPLS-OVER-GMPLS].
          This is a modification of the augmented model where the layer
          border routers have visibility into both layers, but no routing
          information is otherwise exchanged between routing protocol
          instances. This architectural model is particularly suited to the
          MPLS-GMPLS-MPLS island model for PSC and non-PSC GMPLS islands.
          Signaling interworking is required as described for the peer model.
     
     
     
     
     
     
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     5.1.2. Routing Interworking
     
        Migration strategies may necessitate some interworking between MPLS
        and GMPLS routing protocols. GMPLS extends the TE information
        advertised by the IGPs to include non-PSC information and extended
        PSC information. Because the GMPLS information is provided as
        additional TLVs that are carried along with the MPLS information,
        MPLS LSRs are able to "see" all GMPLS LSRs as though they were MPLS
        PSC LSRs. They will also see other GMPLS information, but will ignore
        it, flooding it transparently across the MPLS network for use by
        other GMPLS LSRs.
     
        - Routing separation is achieved in the overlay and border peer
          models. This is convenient since only the border nodes need to be
          aware of the different protocol variants, and no mapping is
          required. It is suitable to the MPLS-GMPLS-MPLS and GMPLS-MPLS-
          GMPLS island migration models.
     
        - Direct distribution involves the flooding of MPLS routing
          information into a GMPLS network, and GMPLS routing information
          into an MPLS network. The border nodes make no attempt to filter
          the information. This mode of operation relies on the fact that
          MPLS routers will ignore, but continue to flood, GMPLS routing
          information that they do not understand. The presence of
          additional GMPLS routing information will not interfere with the
          way that MPLS LSRs select routes, and although this is not a
          problem in a PSC-only network, it could cause problems in a peer
          architecture network that includes non-PSC nodes as the MPLS nodes
          are not capable of determining the switching types of the other
          LSRs and will attempt to signal end-to-end LSPs assuming all LSRs
          to be PSC. This fact would require island border nodes to take
          triggered action to set up tunnels across islands of different
          switching capabilities.
     
          GMPLS LSRs might be impacted by the absence of GMPLS-specific
          information in advertisements initiated by MPLS LSRs. Specific
          procedures might be required to ensure consistent behavior by
          GMPLS nodes. If this issue is addressed, then direct distribution
          can be used in all migration models (except the overlay and border
          peer architectural models where the problem does not arise).
     
        - Protocol mapping converts routing advertisements so that they can
          be received in one protocol and transmitted in the other. For
          example, a GMPLS routing advertisement could have all of its
          GMPLS-specific information removed and could be flooded as an MPLS
          advertisement. This mode of interworking would require careful
          standardization of the correct behavior especially where an MPLS
     
     
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          advertisement requires default values of GMPLS-specific fields to
          be generated before the advertisement can be flooded further.
          There is also considerable risk of confusion in closely meshed
          networks where many LSRs have MPLS and GMPLS capable interfaces.
          This option for routing interworking during migration is NOT
          RECOMMENDED for any migration model. Note that converting GMPLS-
          specific sub-TLVs to MPLS-specific ones but not stripping the
          GMPLS-specific ones is considered as a variant of the proposed
          solution in the previous bullet (Unknown sub-TLVs should be
          ignored [RFC3630] but must continue to be flooded).
     
        - Ships in the night refers to a mode of operation where both MPLS
          and GMPLS routing protocol variants are operated in the same
          network at the same time as separate routing protocol instances.
          The two instances are independent and are used to create routing
          adjacencies between LSRs of the same type. This mode of operation
          may be appropriate to the integrated migration model.
     
     5.1.3. Signaling Interworking
     
        Signaling protocols are used to establish LSPs and are the principal
        concern for interworking during migration. Issues of compatibility
        arise because of differences in the encodings and codepoints used by
        MPLS and GMPLS signaling, but also because of differences in
        functionality provided by MPLS and GMPLS.
     
        - Tunneling and stitching [STITCH](GMPLS-PSC case) mechanisms
          provide the potential to avoid direct protocol interworking during
          migration in the island model, because protocol elements are
          transported transparently across migration islands without being
          inspected. However, care may be needed to achieve functional
          mapping in these modes of operation since one set of features may
          need to be supported across a network designed to support a
          different set of features. In general, this is easily achieved for
          the MPLS-GMPLS-MPLS model, but may be hard to achieve in the
          GMPLS-MPLS-GMPLS model. For example, when end-to-end bidirectional
          LSPs are requested, since the MPLS island does not support
          bidirectional LSPs.
     
          Note that tunneling and stitching are not available in unbalanced
          island models because in these cases the LSP end points use
          different protocols.
     
        - Protocol mapping is the conversion of signaling messages between
          MPLS and GMPLS. This mechanism requires careful documentation of
          the protocol fields and how they are mapped. This is relatively
          straightforward in the MPLS-GMPLS unbalanced island model for LSPs
     
     
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          signaled in the MPLS-GMPLS direction. However, it may be more
          complex for LSPs signaled in the opposite direction, and this will
          lead to considerable complications for providing GMPLS services
          over the MPLS island and for terminating those services at an
          egress LSR that is not GMPLS-capable. Further, in balanced island
          models, and in particular where there are multiple small
          (individual node) islands, the repeated conversion of signaling
          parameters may lead to loss of information (and functionality) or
          mis-requests.
     
        - Ships in the night could be used in the integrated migration model
          to allow MPLS-capable LSRs to establish LSPs using MPLS signaling
          protocols and GMPLS LSRs to establish LSPs using GMPLS signaling
          protocols. LSRs that can handle both sets of protocols could work
          with both types of LSRs, and no conversion of protocols would be
          needed.
     
     
     
     6.  Manageability Considerations
     
        Attention should be given during migration planning to how the
        network will be managed during and after migration. For example, will
        the LSRs of different protocol capabilities be managed separately or
        as one management domain. For example, in the Island Model, it is
        possible to consider managing islands of one capability separately
        from the surrounding sea. In the case of islands that have different
        switching capabilities, it is possible that the islands already have
        separate management in place before the migration: the resultant
        migrated network may seek to merge the management or to preserve the
        separation.
     
     6.1. Control of Function and Policy
     
        The most critical control functionality to be applied is at the
        moment of changeover between different levels of protocol support.
        Such a change may be made without service halt or during a period of
        network maintenance.
     
        Where island boundaries exist, it must be possible to manage the
        relationships between protocols and to indicate which interfaces
        support which protocols on a border LSR. Further, island borders are
        a natural place to apply policy, and management should allow
        configuration of such policies.
     
     
     
     
     
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     6.2. Information and Data Models
     
        No special information or data models are required to support
        migration, but note that migration in the control plane implies
        migration from MPLS management tools to GMPLS management tools.
        During migration, therefore, it may be necessary for LSRs and
        management applications to support both MPLS and GMPLS management
        data.
     
        The GMPLS MIB modules are designed to allow support of the MPLS
        protocols and built on the MPLS MIB modules through extensions and
        augmentations. This may make it possible to migrate management
        applications ahead of the LSRs that they manage.
     
     6.3. Liveness Detection and Monitoring
     
        Migration will not impose additional issues for OAM above those that
        already exist for inter-domain OAM and for OAM across multiple
        switching capabilities.
     
        Note, however, that if a flat PSC MPLS network is migrated using the
        island model, and is treated as a layered network using tunnels to
        connect across GMPLS islands, then requirements for a multi-layer OAM
        technique may be introduced into what was previously defined in the
        flat OAM problem-space. The OAM framework of MPLS/GMPLS interworking
        will need further consideration.
     
     6.4. Verifying Correct Operation
     
        The concerns for verifying correct operation (and in particular
        correct connectivity) are the same as for liveness detection and
        monitoring. Specifically, the process of migration may introduce
        tunneling or stitching [STITCH] into what was previously a flat
        network.
     
     6.5. Requirements on Other Protocols and Functional Components
     
        No particular requirements are introduced on other protocols. As it
        has been observed, the management components may need to migrate in
        step with the control plane components, but this does not impact the
        management protocols, just the data that they carry.
     
        It should also be observed that providing signaling and routing
        connectivity across a migration island in support of a layered
        architecture may require the use of protocol tunnels (such as GRE)
        between island border nodes. Such tunnels may impose additional
        configuration requirements at the border nodes.
     
     
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     6.6. Impact on Network Operation
     
        The process of migration is likely to have significant impact on
        network operation while migration is in progress. The main objective
        of migration planning should be to reduce the impact on network
        operation and on the services perceived by the network users.
     
        To this end, planners should consider reducing the number of
        migration steps that they perform, and minimizing the number of
        migration islands that are created.
     
        A network manager may prefer the island model especially when
        migration will extend over a significant operational period because
        it allows the different network islands to be administered as
        separate management domains. This is particularly the case in the
        overlay, augmented network and border peer models where the details
        of the protocol islands remain hidden from the surrounding LSRs.
     
     6.7. Other Considerations
     
        A migration strategy may also imply moving an MPLS state to a GMPLS
        state for an in-service LSP. This may arise once all of the LSRs
        along the path of the LSP have been updated to be both MPLS and
        GMPLS-capable. Signaling mechanisms to achieve the replacement of an
        MPLS LSP with a GMPLS LSP without disrupting traffic exist through
        make-before-break procedures [RFC3209] and [RFC3473], and should be
        carefully managed under operator control.
     
     
     
     7. Security Considerations
     
        Security and confidentiality is often applied (and attacked) at
        administrative boundaries. Some of the models described in this
        document introduce such boundaries, for example between MPLS and
        GMPLS islands. These boundaries offer the possibility of applying or
        modifying the security as when crossing an IGP area or AS boundary,
        even though these island boundaries might lie within an IGP area or
        AS.
     
        No changes are proposed to the security procedures built into MPLS
        and GMPLS signaling and routing. GMPLS signaling and routing inherit
        their security mechanisms from MPLS signaling and routing without any
        changes. Hence, there will be no additional issues with security in
        interworking scenarios. Further, since the MPLS and GMPLS signaling
        and routing security is provided on a hop-by-hop basis, and since all
        signaling and routing exchanges described in this document for use
     
     
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        between any pair of LSRs are based on either MPLS or GMPLS, there are
        no changes necessary to the security procedures.
     
     8. IANA Considerations
     
        This informational framework document makes no requests for IANA
        action.
     
     9. Acknowledgements
     
        The authors are grateful to Daisaku Shimazaki for discussion during
        initial work on this document. The authors are grateful to Dean Cheng
        and Adrian Farrel for their valuable comments.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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     10. Editor's Addresses
     
        Kohei Shiomoto, Editor
        NTT
        Midori 3-9-11
        Musashino, Tokyo 180-8585, Japan
        Phone: +81 422 59 4402
        Email: shiomoto.kohei@lab.ntt.co.jp
     
     11. Authors' Addresses
     
        Dimitri Papadimitriou
        Alcatel
        Francis Wellensplein 1,
        B-2018 Antwerpen, Belgium
        Phone: +32 3 240 8491
        Email: dimitri.papadimitriou@alcatel-lucent.be
     
        Jean-Louis Le Roux
        France Telecom
        av Pierre Marzin 22300
        Lannion, France
        Phone: +33 2 96 05 30 20
        Email: jeanlouis.leroux@orange-ftgroup.com
     
        Deborah Brungard
        AT&T
        Rm. D1-3C22 - 200 S. Laurel Ave.
        Middletown, NJ 07748, USA
        Phone: +1 732 420 1573
        Email: dbrungard@att.com
     
        Kenji Kumaki
        KDDI Corporation
        Garden Air Tower
        Iidabashi, Chiyoda-ku,
        Tokyo 102-8460, JAPAN
        Phone: +81-3-6678-3103
        Email: ke-kumaki@kddi.com
     
        Zafar Alli
        Cisco Systems, Inc.
        EMail: zali@cisco.com
     
        Eiji Oki
        NTT
        Midori 3-9-11
     
     
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        Musashino, Tokyo 180-8585, Japan
        Phone: +81 422 59 3441
        Email: oki.eiji@lab.ntt.co.jp
     
        Ichiro Inoue
        NTT
        Midori 3-9-11
        Musashino, Tokyo 180-8585, Japan
        Phone: +81 422 59 3441
        Email: inoue.ichiro.lab.ntt.co.jp
     
        Tomohiro Otani
        KDDI Laboratories
        Email: otani@kddilabs.jp
     
     
     12. References
     
     12.1. Normative References
     
        [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
                  Requirement Levels," BCP 14, IETF RFC 2119, March 1997.
     
        [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
                  and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
                  Tunnels", RFC 3209, December 2001.
     
        [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
                  (GMPLS) Signaling Resource ReserVation Protocol-Traffic
                  Engineering (RSVP-TE) Extensions ", RFC 3473, January 2003.
     
        [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering
                  (TE) Extensions to OSPF Version 2", RFC 3630, September
                  2003.
     
        [RFC3784] Smit, H. and T. Li, "Intermediate System to Intermediate
                  System (IS-IS) Extensions for Traffic Engineering (TE)",
                  RFC 3784, June 2004.
     
        [RFC3945] Mannie, E., "Generalized Multi-Protocol Label Switching
                  Architecture", RFC 3945, October 2004.
     
        [RFC4090] Pan, P., Swallow, G. and Atlas, A., "Fast Reroute
                  Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005.
     
     
     
     
     
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        [RFC4872] Lang, J. P., Rekhter, Y., Papadimitriou, D. (Editors), "
                  RSVP-TE Extensions in support of End-to-End Generalized
                  Multi-Protocol Label Switching (GMPLS)-based Recovery",
                  RFC4872, May 2007.
     
        [RFC4873] Berger, L., Bryskin, I., Papadimitriou, D., Farrel, A.,
                  "GMPLS Based Segment Recovery", RFC 4873, May 2007.
     
        [TE-NODE-CAPS] Vasseur, Le Roux, editors " IGP Routing Protocol
                  Extensions for Discovery of Traffic Engineering Node
                  Capabilities", draft-ietf-ccamp-te-node-cap, work in
                  progress.
     
     12.2. Informative References
     
        [RFC4206] Kompella, K., and Rekhter, Y., "Label Switched Paths (LSP)
                  Hierarchy with Generalized Multi-Protocol Label Switching
                  (GMPLS) Traffic Engineering (TE)", RFC 4206, October 2005.
     
        [MLN-REQ] Shiomoto, K., Papadimitriou, D., Le Roux, J.L., Vigoureux,
                  M., Brungard, D., "Requirements for GMPLS-based multi-
                  region and multi-layer networks (MRN/MLN)", draft-ietf-
                  ccamp-gmpls-mln-reqs, work in progress.
     
        [STITCH] Ayyangar, A., Vasseur, JP. "Label Switched Path Stitching
                  with Generalized MPLS Traffic Engineering", draft-ietf-
                  ccamp-lsp-stitching, work in progress.
     
        [RFC4726] Farrel, A., Vasseur, J.P., Ayyangar, A., " A Framework for
                  Inter-Domain Multiprotocol Label Switching Traffic
                  Engineering", RFC4726, November 2006.
     
        [MPLS-OVER-GMPLS] Kumaki, K., et al., " Interworking Requirements to
                  Support operation of MPLS-TE over GMPLS networks", draft-
                  ietf-ccamp-mpls-gmpls-interwork-reqts, work in progress.
     
     
     
     13. Full Copyright Statement
     
        Copyright (C) The IETF Trust (2007).
     
        This document is subject to the rights, licenses and restrictions
        contained in BCP 78, and except as set forth therein, the authors
        retain all their rights.
     
     
     
     
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        This document and the information contained herein are provided on an
        "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
        OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
        THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
        OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
        THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
        WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
     
     
     
     14. Intellectual Property
     
        The IETF takes no position regarding the validity or scope of any
        Intellectual Property Rights or other rights that might be claimed to
        pertain to the implementation or use of the technology described in
        this document or the extent to which any license under such rights
        might or might not be available; nor does it represent that it has
        made any independent effort to identify any such rights.  Information
        on the procedures with respect to rights in RFC documents can be
        found in BCP 78 and BCP 79.
     
        Copies of IPR disclosures made to the IETF Secretariat and any
        assurances of licenses to be made available, or the result of an
        attempt made to obtain a general license or permission for the use of
        such proprietary rights by implementers or users of this
        specification can be obtained from the IETF on-line IPR repository at
        http://www.ietf.org/ipr.
     
        The IETF invites any interested party to bring to its attention any
        copyrights, patents or patent applications, or other proprietary
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        this standard.  Please address the information to the IETF at ietf-
        ipr@ietf.org.
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
     
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