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              draft-caviglia-ccamp-pc-and-sc-reqs-04.txt September 2006

   Network Working Group
   Internet Draft                                        Diego Caviglia
   Intended Status: Informational                         Dino Bramanti
                                                                 Dan Li
   Document:                                                     Huawei

   Expires:                                                  March 2007

     Requirements for the Conversion Between Permanent Connections and
    Switched Connections in a Generalized Multiprotocol Label Switching
                              (GMPLS) Network

Status of this Memo

   By submitting this Internet-Draft, each author represents that any
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   From a Carrier perspective, the possibility of turning a Permanent
   Connection (PC) into a Soft Permanent Connection (SPC) and vice
   versa, without actually affecting Data Plane traffic being carried
   over it, is a valuable option. In other terms, such operation can be
   seen as a way of transferring the ownership and control of an
   existing and in-use Data Plane connection between the Management
   Plane and the Control Plane, leaving its Data Plane state untouched.

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   This memo sets out the requirements for such procedures within a
   Generalized Multiprotocol Label Switching (GMPLS) network.

Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   this document are to be interpreted as described in RFC-2119 [1].

Table of Contents

   1  Introduction...................................................3
   1.1  Motivation..................................................3
   1.2  Label Switched Path Terminology.............................3
   1.3  LSP within GMPLS Control Plane..............................4
   1.4  Resource Ownership..........................................4
   1.5  Setting Up a GMPLS Controlled Network.......................5
   2  Typical Use Cases..............................................5
   2.1  PC to SC/SPC Conversion.....................................5
   2.2  SC to PC Conversion.........................................6
   3  Requirements...................................................6
   3.1  Data Plane LSP Consistency..................................6
   3.2  No Disruption of User Traffic...............................6
   3.3  Transfer from Management Plane to Control Plane.............6
   3.4  Transfer from Control Plane to Management Plane.............6
   3.5  Synchronization of state among nodes during conversion......7
   3.6  Support of Soft Permanent Connections.......................7
   3.7  Failure of Transfer.........................................7
   4  Security Considerations........................................7
   5  IANA Consideration.............................................7
   6  References.....................................................8
   6.1  Normative References........................................8
   6.2  Informative References......................................8
   7  Acknowledgments................................................8

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1    Introduction

   In a typical, traditional transport network scenario, Data Plane
   connections between two endpoints are controlled by means of a
   Network Management System (NMS) operating within the Management
   Plane (MP). The NMS/MP is the owner of such transport connections,
   being responsible of their setup, teardown, and maintenance.
   Provisioned connections of this kind, initiated and managed by the
   Management Plane, are known as Permanent Connections (PCs).

   When the setup, teardown, and maintenance of connections is achieved
   by means of a signaling protocol owned by the Control Plane such
   connections are known as Switched Connections (SCs).

   In many deployments a hybrid connection type will be used. A Soft
   Permanent Connection (SPC) is a combination of a permanent
   connection segment at the source user-to-network side, a permanent
   connection segment at the destination user-to-network side, and a
   switched connection segment within the core network. The permanent
   parts of the SPC are owned by the Management Plane, and the switched
   parts are owned by the Control Plane.

1.1  Motivation

   The main motivation for this work is the LSP conversion from
   Management Plane to Control Plane. The objective is to be able to
   introduce a control plane into an existing network without
   disrupting user traffic.
   Conversion from the Management Plane to Control Plane is proposed as
   a mandatory requirement while the conversion from the Control Plane
   to Management is seen as a nice to have feature. The requirement for
   LSP conversion from Control Plane to Management Plane should be
   scoped as a back-out procedure.

1.2  Label Switched Path Terminology

   A Label Switched Path (LSP) has different semantics depending on the
   plane in which it the term is used.

   In the Data Plane, an LSP indicates the Data Plane forwarding path.
   It defines the forwarding or switching operations at each network
   entity. It is the sequence of data plane resources (links, labels,
   cross-connects) that achieves end-to-end data transport.

   In the Management Plane, an LSP is the management state information
   (such as the connection attributes and path information)associated
   with and necessary for the creation and maintenance of a Data Plane

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   In the Control Plane, an LSP is the control plane state information
   (such as Path and Resv state)associated with and necessary for the
   creation and maintenance of a Data Plane connection.

   A permanent connection has an LSP presence in the Data Plane and the
   Management Plane. A switched connection has an LSP presence in the
   Data Plane and the Control Plane. An SPC has LSP presence in the
   Data Plane for its entire length, but has Management Plane presence
   for part of its length and Control Plane presence for part of its
   In this document, when we talk about the LSP conversion between
   Control plane and Management plane, we mainly focus on the
   conversion of control plane state information and management state

1.3  LSP within GMPLS Control Plane

   Generalized Multiprotocol Label Switching (GMPLS)[2], [3] defines a
   powerful Control Plane architecture for transport networks. This
   includes both routing and signaling protocols for the creation and
   maintenance of Label Switched Paths (LSPs) in networks whose Data
   Plane is based on different technologies such as optical TDM
   transport ad WDM.

1.4  Resource Ownership

   A resource used by an LSP is said to be 'owned' by the plane that
   was used to set up the LSP through that part of the network. Thus,
   all the resources used by a permanent connection are owned by the
   Management Plane, and all the resources used by a switched
   connection are owned by the Control Plane. The resources used by an
   SPC are divided between the Management Plane (for the resources used
   by the permanent connection segments at the edge of the network) and
   the Control Plane (for the resources used by the switched segment in
   the middle of the network).

   The division of resources available for ownership by the Management
   and Control Planes is an architectural issue. A carrier may decide
   to pre-partition the resources at a network entity so that LSPs
   under Management Plane control use one set of resources and LSPs
   under Control Plane control use another set of resources. Other
   carriers may choose to make this distinction resource-by-resource as
   LSPs are established.

   It should be noted, however, that even when a resource is owned by
   the Control Plane it will usually be the case that the Management
   Plane has a controlling interest in the resource. Consider, for

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   example, that in the event of a Control Plane failure, the
   Management Plane needs to be able to de-provision resources. Also
   consider the basic safety requirements that imply that management
   commands must be available to set laser out of service.

1.5  Setting Up a GMPLS Controlled Network

   The implementation of a new network using a Generalized
   Multiprotocol Label Switching (GMPLS) Control Plane may be
   considered as a green field deployment. But in many cases it is
   desirable to introduce a GMPLS Control Plane into an existing
   transport network that is already populated with permanent
   connections under Management Plane control.

   In a mixed scenario, permanent connections owned by the Management
   Plane and switched connections owned by the Control Plane have to
   coexist within the network.

   It is also desirable to transfer the control of connections from the
   Management Plane to the Control Plane so that connections that were
   originally under the control of an NMS are now under the control of
   the GMPLS protocols. In case such connections are in service, such
   conversion must be performed in a way that does not affect traffic.

   Since attempts to move a LSP under GMPLS control might fail due to a
   number of reasons outside the scope of this draft, it is also
   advisable to have a mechanism to convert the control of an LSP back
   to the Management Plane, in fact undoing the whole process.

   Note that a permanent connection may be converted to a switched
   connection or to an SPC, and an SPC may be converted to a switched
   connection as well(PC to SC, PC to SPC, and SPC to SC). So the
   reverse mappings may be also needed (SC to PC, SC to SPC, and SPC to

2    Typical Use Cases

2.1  PC to SC/SPC Conversion

   A typical scenario where a PC to SC (or SPC) procedure can be a
   useful option is at the initial stage of Control Plane deployment in
   an existing network. In such a case all the network connections,
   possibly carrying traffic, are already set up as PCs and are owned
   by the Management Plane.

   Next step in such conversion process presents a similar scenario
   where the network is partially controlled by the Management Plane
   and partially controlled by the Control Plane (PCs and SCs/SPCs

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   coexist). In this case a network upgrade by a Control Plane coverage
   extension may be required.

   In both cases the point is that a connection, set up and owned by
   the Management Plane, may need to be transferred to Control Plane
   control. If a connection is carrying traffic, its transfer has to be
   done without any disruption to the Data Plane traffic.

2.2  SC to PC Conversion

   The main reason making a SC to PC conversion interesting is to give
   an operator the chance of undoing somehow the action represented by
   the above introduced PC to SC conversion.

   In other words the SC to PC conversion is a back-out procedure and
   as such is not considered mandatory in this document, still being a
   useful functional resource.

   Again it is worth stressing the requirement that such `SPC to PC`
   conversion is achieved without any effect on the associated Data
   Plane state so that the connection continues to be operational and
   to carry traffic during the transition.

3    Requirements

   This section sets out the basic requirements for procedures and
   processes that are used to perform the functions this document is

3.1  Data Plane LSP Consistency

   The Data Plane LSP, staying in place throughout the whole transfer
   process, MUST follow the same path through the network and MUST use
   the same network resources.

3.2  No Disruption of User Traffic

   The transfer process MUST NOT cause any disruption of user traffic
   flowing over the LSP whose control is being transferred or any other
   LSP in the network.

3.3  Transfer from Management Plane to Control Plane

   It MUST be possible to transfer the ownership of an LSP from the
   Management Plane to the Control Plane

3.4  Transfer from Control Plane to Management Plane

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   It SHOULD be possible to transfer the ownership of an LSP from the
   Control Plane to the Management Plane.

3.5  Synchronization of state among nodes during conversion

   It MUST be assured that the state of the LSP is synchronized among
   all nodes traversed by it before proceeding to the conversion.

3.6  Support of Soft Permanent Connections

   It MUST be possible to segment an LSP such that it is converted to
   or from an SPC.

3.7  Failure of Transfer

   It MUST be possible for a transfer from one plane to the other to
   fail in a non-destructive way leaving the ownership unchanged and
   without impacting traffic.

   If during the transfer procedure some issues arise causing an
   unsuccessful or incomplete, unexpected result it MUST be assured
   that at the end:
   1) Traffic over Data Plane is not affected
   2) The LSP status is consistent in all the TNEs involved in the

   Point 2 above assures that, even in case of some failure during the
   transfer, the state of the affected LSP is brought back to the
   initial one and it is fully under control of the owning entity.

4    Security Considerations

   Allowing control of an LSP to be taken away from a plane introduces
   another way in which services may be disrupted by malicious

   It is expected that any solution to the requirements in this
   document will utilize the security mechanisms inherent in the
   Management Plane and Control Plane protocols, and no new security
   mechanisms are needed if these tools are correctly used.

   Note also that implementations may enable policy components to help
   determine whether individual LSPs may be transferred between planes.

5    IANA Considerations

   This requirement document makes no requests for IANA action.

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6    References

6.1  Normative References

    [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement
   Levels", BCP 14, RFC 2119, March 1997

6.2   Informative References

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

   [3] L. Berger (Ed.) "Generalized Multi-Protocol Label Switching
   (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering
   (RSVP-TE) Extensions", RFC 3473, January 2003

7    Acknowledgments

   We whish to thank the following people (listed randomly) Adrian
   Farrel for his editorial assistance to prepare this draft for
   publication, Dean Cheng and Julien Meuric, Dimitri Papadimitriou,
   Deborah Brungard, Igor Bryskin, Lou Berger, Don Fedyk, John Drake
   and Vijay Pandian for their suggestions and comments on the CCAMP

8  Authors' Addresses

      Diego Caviglia
      Via A. Negrone 1/A
      Genova-Sestri Ponente, Italy
      Phone: +390106003738
      Email: diego.caviglia@marconi.com

      Dino Bramanti
      Via Moruzzi 1
      C/O Area Ricerca CNR
      Pisa, Italy
      Email: dino.bramanti@marconi.com

      Nicola Ciulli
      Corso Italia 116
      56125 Pisa, Italy
      Email: n.ciulli@nextworks.it

      Dan Li

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      Huawei Technologies Co., LTD.
      Huawei Base, Bantian, Longgang,
      Shenzhen 518129 P.R.China
      Tel: +86-755-28972910

      Han Li
      China Mobile Communications Co.
      53A Xibianmennei Ave. Xuanwu District
      Beijing 100053 P.R. China
      Tel: +86-10-66006688 ext. 3092

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