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Network Working Group D. Caviglia Request for Comments: 5493 D. Bramanti Category: Informational Ericsson

                                                                 D. Li
                                         Huawei Technologies Co., Ltd.
                                                            D. McDysan
                                                               Verizon
                                                            April 2009
              Requirements for the Conversion between
        Permanent Connections and Switched Connections in a
     Generalized Multiprotocol Label Switching (GMPLS) Network

Status of This Memo

 This memo provides information for the Internet community.  It does
 not specify an Internet standard of any kind.  Distribution of this
 memo is unlimited.

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 document authors.  All rights reserved.
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 Provisions Relating to IETF Documents in effect on the date of
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 and restrictions with respect to this document.
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 Contributions published or made publicly available before November
 10, 2008.  The person(s) controlling the copyright in some of this
 material may not have granted the IETF Trust the right to allow
 modifications of such material outside the IETF Standards Process.
 Without obtaining an adequate license from the person(s) controlling
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 than English.

Caviglia, et al. Informational [Page 1] RFC 5493 Conversion between PC and SC in GMPLS April 2009

Abstract

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

Table of Contents

 1. Introduction ....................................................3
    1.1. Conventions Used in This Document ..........................3
 2. Label Switched Path Terminology .................................3
 3. LSP within GMPLS Control Plane ..................................4
    3.1. Resource Ownership .........................................4
    3.2. Setting Up a GMPLS-Controlled Network ......................5
 4. Typical Use Cases ...............................................6
    4.1. PC-to-SC/SPC Conversion ....................................6
    4.2. SC-to-PC Conversion ........................................6
 5. Requirements ....................................................7
    5.1. Data Plane LSP Consistency .................................7
    5.2. No Disruption of User Traffic ..............................7
    5.3. Transfer from Management Plane to Control Plane ............7
    5.4. Transfer from Control Plane to Management Plane ............7
    5.5. Synchronization of State among Nodes during Conversion .....7
    5.6. Support of Soft Permanent Connections ......................8
    5.7. Failure of Transfer ........................................8
 6. Security Considerations .........................................8
 7. Contributors ....................................................9
 8. Acknowledgments .................................................9
 9. References ......................................................9
    9.1. Normative References .......................................9
    9.2. Informational References ..................................10

Caviglia, et al. Informational [Page 2] RFC 5493 Conversion between PC and SC in GMPLS April 2009

1. Introduction

 In a typical, traditional transport network scenario, data plane
 connections between two end-points 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 type, initiated and managed by the management
 plane, are known as permanent connections (PCs) [G.8081].
 When the setup, teardown, and maintenance of connections are achieved
 by means of a signaling protocol owned by the control plane (CP),
 such connections are known as switched connections (SCs) [G.8081].
 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 [G.8081].
 Note, some aspects of a control-plane-initiated connection must be
 capable of being queried/controlled by the management plane.  These
 aspects should be independent of how the connection was established.

1.1. Conventions Used in This Document

 Although this requirements document is an informational document, not
 a protocol specification, 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] for clarity of
 requirement specification.

2. Label Switched Path Terminology

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

Caviglia, et al. Informational [Page 3] RFC 5493 Conversion between PC and SC in GMPLS April 2009

 In the management plane, an LSP is the management plane state
 information (such as the connection attributes and path information)
 associated with and necessary for the creation and maintenance of a
 data plane connection.
 In the control plane, an LSP is the control plane state information
 (such as the RSVP-TE [RFC3473] 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 an LSP presence in the
 data plane for its entire length, but has a management plane presence
 for part of its length and a control plane presence for part of its
 length.
 In this document, when we discuss the LSP conversion between
 management plane and control plane, we mainly focus on the conversion
 of control plane state information and management plane state
 information.

3. LSP within GMPLS Control Plane

 GMPLS ([RFC3471], [RFC3473], and [RFC3945]) defines a control plane
 architecture for transport networks.  This includes both routing and
 signaling protocols for the creation and maintenance of LSPs in
 networks whose data plane is based on different technologies, such as
 Time Division Multiplexing (SDH/SONET, G.709 at ODUk level) and
 Wavelength Division Multiplexing (G.709 at OCh level).

3.1. 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 connection
 segments 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

Caviglia, et al. Informational [Page 4] RFC 5493 Conversion between PC and SC in GMPLS April 2009

 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.  For example,
 consider the basic safety requirements that management commands must
 be able to put a laser out of service.

3.2. 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 an LSP under GMPLS control might fail due to a
 number of reasons outside the scope of this document, it is also
 highly desirable to have a mechanism to convert the control of an LSP
 back to the management plane.
 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 also be needed (SC to PC, SPC to PC, and SC to
 SPC).
 Conversion to/from control/management will occur in MIBs or in
 information stored on the device (e.g., cross-connect, label
 assignment, label stacking, etc.) and is identified as either
 initiated by a specific control protocol or by manual operation
 (i.e., via an NMS).  When converting, this hop-level owner
 information needs to be completed for all hops.  If conversion cannot
 be done for all hops, then the conversion must be done for no hops,

Caviglia, et al. Informational [Page 5] RFC 5493 Conversion between PC and SC in GMPLS April 2009

 the state of the hop-level information must be restored to that
 before the conversion was attempted, and an error condition must be
 reported to the management system.
 In either case of conversion, the management plane shall initiate the
 change.  When converting from a PC to an SC, the management system
 must indicate to each hop that a control protocol is now to be used,
 and then configure the data needed by the control protocol at the
 connection endpoints.  When converting from an SC to a PC, the
 management plane must change the owner of each hop.  Then the
 instance in the control plane must be removed without affecting the
 data plane.
 The case where the CP and/or MP fail at one or more nodes during the
 conversion procedure must be handled in the solution.  If the network
 is viewed as the database of record (including data, control, and
 management plane elements), then a solution that has procedures
 similar to those of a two-phase database commit process may be needed
 to ensure integrity and to support the need to revert to the state
 prior to the conversion attempt if there is a CP and/or MP failure
 during the attempted conversion.

4. Typical Use Cases

4.1. 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.
 At a latter stage, when the network is partially controlled by the
 management plane and partially controlled by the control plane (PCs
 and SCs/SPCs coexist) and it is desired to extend the control plane,
 a PC-to-SC procedure can be used to transfer a PC or SPC to a SC.
 In both cases, a connection, set up and owned by the management
 plane, needs to be transferred to control plane control.  If a
 connection is carrying traffic, its control transfer has to be done
 without any disruption to the data plane traffic.

4.2. SC-to-PC Conversion

 The main need for an SC-to-PC conversion is to give an operator the
 capability of undoing the action of the above introduced PC-to-SC
 conversion.

Caviglia, et al. Informational [Page 6] RFC 5493 Conversion between PC and SC in GMPLS April 2009

 In other words, the SC-to-PC conversion is a back-out procedure and
 as such is not specified as mandatory in this document, but it is
 still a highly desirable function.
 Again, it is worth stressing the requirement that such an SPC-to-PC
 conversion needs to be 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.

5. Requirements

 This section sets out the basic requirements for procedures and
 processes that are used to perform the functions of this document.
 Notation from [RFC2119] is used to clarify the level of each
 requirement.

5.1. Data Plane LSP Consistency

 The data plane LSP MUST stay in place throughout the whole control
 transfer process.  It MUST follow the same path through the network
 and MUST use the same network resources.

5.2. 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 over any
 other LSP in the network.
 SC-to-PC conversion and vice-versa SHALL occur without generating
 alarms towards the end users or the NMS.

5.3. 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.

5.4. Transfer from Control Plane to Management Plane

 It SHOULD be possible to transfer the ownership of an LSP from the
 control plane to the management plane.

5.5. 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 the conversion is considered
 complete.

Caviglia, et al. Informational [Page 7] RFC 5493 Conversion between PC and SC in GMPLS April 2009

5.6. Support of Soft Permanent Connections

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

5.7. 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 issues arise causing an unsuccessful
 or unexpected result, it MUST be assured that:
 1.  Traffic over the data plane is not affected.
 2.  The LSP status is consistent in all the network nodes involved in
     the procedure.
 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 is fully under the control of the owning entity.

6. Security Considerations

 Allowing control of an LSP to be taken away from a plane introduces a
 possible way in which services may be disrupted by malicious
 intervention.
 A solution to the requirements in this document will utilize the
 security mechanisms supported by the management plane and GMPLS
 control plane protocols, and no new security requirements over the
 general requirements described in [RFC3945] are introduced.  It is
 expected that solution documents will include an analysis of the
 security issues introduced by any new protocol extensions.
 The management plane interactions MUST be supported through protocols
 that can offer adequate security mechanisms to secure the
 configuration and protect the operation of the devices that are
 managed.  These mechanisms MUST include at least cryptographic
 security and the ability to ensure that the entity giving access to
 configuration parameters is properly configured to give access only
 to those principals (users) that have legitimate rights to
 read/create/change/delete the parameters.  IETF standard management
 protocols (Netconf [RFC4741] and SNMPv3 [RFC3410]) offer these
 mechanisms.

Caviglia, et al. Informational [Page 8] RFC 5493 Conversion between PC and SC in GMPLS April 2009

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

7. Contributors

 Nicola Ciulli
 NextWorks
 Corso Italia 116
 56125 Pisa, Italy
 EMail: n.ciulli@nextworks.it
 Han Li
 China Mobile Communications Co.
 53 A Xibianmennei Ave. Xuanwu District
 Deijing 100053 P.R. China
 Phone: 10-66006688 ext.3092
 EMail: lihan@chinamobile.com
 Daniele Ceccarelli
 Ericsson
 Via A. Negrone 1/A
 Genova-Sestri Ponente, Italy
 Phone: +390106002515
 EMail: daniele.ceccarelli@ericsson.com

8. Acknowledgments

 We wish to thank the following people (listed randomly): Adrian
 Farrel for his editorial assistance to prepare this document for
 publication; Dean Cheng, 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
 list.

9. References

9.1. Normative References

 [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
            Requirement Levels", BCP 14, RFC 2119, March 1997.
 [RFC3410]  Case, J., Mundy, R., Partain, D., and B.
            Stewart,"Introduction and Applicability Statements for
            Internet-Standard Management Framework", RFC 3410,
            December 2002.

Caviglia, et al. Informational [Page 9] RFC 5493 Conversion between PC and SC in GMPLS April 2009

9.2. Informative References

 [RFC3471]  Berger, L., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Signaling Functional Description", RFC
            3471, January 2003.
 [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Signaling Resource ReserVation
            Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC
            3473, January 2003.
 [RFC3945]  Mannie, E., Ed., "Generalized Multi-Protocol Label
            Switching (GMPLS) Architecture", RFC 3945, October 2004.
 [RFC4741]  Enns, R., Ed., "NETCONF Configuration Protocol", RFC 4741,
            December 2006.
 [G.8081]   International Telecommunications Union, "Terms and
            definitions for Automatically Switched Optical Networks
            (ASON)", Recommendation G.8081/Y.1353, June 2004.

Caviglia, et al. Informational [Page 10] RFC 5493 Conversion between PC and SC in GMPLS April 2009

Authors' Addresses

 Diego Caviglia
 Ericsson
 Via A. Negrone 1/A
 Genova - Sestri Ponente
 Italy
 EMail: diego.caviglia@ericsson.com
 Dino Bramanti
 Ericsson
 Via Moruzzi 1 C/O Area Ricerca CNR
 Pisa
 Italy
 EMail: dino.bramanti@ericsson.com
 Dan Li
 Huawei Technologies Co., Ltd.
 Shenzhen 518129
 Huawei Base, Bantian, Longgang
 China
 EMail: danli@huawei.com
 Dave McDysan
 Verizon
 Ashburn, VA
 USA
 EMail: dave.mcdysan@verizon.com

Caviglia, et al. Informational [Page 11]

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