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Network Working Group                                        D. CavigliaRequest for Comments: 5493                                   D. BramantiCategory: Informational                                         Ericsson                                                                   D. Li                                           Huawei Technologies Co., Ltd.                                                              D. McDysan                                                                 Verizon                                                              April 2009Requirements for the Conversion betweenPermanent Connections and Switched Connections in aGeneralized Multiprotocol Label Switching (GMPLS) NetworkStatus 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.Copyright Notice   Copyright (c) 2009 IETF Trust and the persons identified as the   document authors.  All rights reserved.   This document is subject toBCP 78 and the IETF Trust's Legal   Provisions Relating to IETF Documents in effect on the date of   publication of this document (http://trustee.ietf.org/license-info).   Please review these documents carefully, as they describe your rights   and restrictions with respect to this document.   This document may contain material from IETF Documents or IETF   Contributions published or made publicly available before November   10, 2008.  The person(s) controlling the copyright in some of this   material may not have granted the IETF Trust the right to allow   modifications of such material outside the IETF Standards Process.   Without obtaining an adequate license from the person(s) controlling   the copyright in such materials, this document may not be modified   outside the IETF Standards Process, and derivative works of it may   not be created outside the IETF Standards Process, except to format   it for publication as an RFC or to translate it into languages other   than English.Caviglia, et al.             Informational                      [Page 1]

RFC 5493         Conversion between PC and SC in GMPLS        April 2009Abstract   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 Contents1. Introduction ....................................................31.1. Conventions Used in This Document ..........................32. Label Switched Path Terminology .................................33. LSP within GMPLS Control Plane ..................................43.1. Resource Ownership .........................................43.2. Setting Up a GMPLS-Controlled Network ......................54. Typical Use Cases ...............................................64.1. PC-to-SC/SPC Conversion ....................................64.2. SC-to-PC Conversion ........................................65. Requirements ....................................................75.1. Data Plane LSP Consistency .................................75.2. No Disruption of User Traffic ..............................75.3. Transfer from Management Plane to Control Plane ............75.4. Transfer from Control Plane to Management Plane ............75.5. Synchronization of State among Nodes during Conversion .....75.6. Support of Soft Permanent Connections ......................85.7. Failure of Transfer ........................................86. Security Considerations .........................................87. Contributors ....................................................98. Acknowledgments .................................................99. References ......................................................99.1. Normative References .......................................99.2. Informational References ..................................10Caviglia, et al.             Informational                      [Page 2]

RFC 5493         Conversion between PC and SC in GMPLS        April 20091.  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 inRFC 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 underCaviglia, 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 Cases4.1.  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 20095.6.  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.com8.  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.  References9.1.  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 20099.2.  Informative References   [RFC3471]  Berger, L., Ed., "Generalized Multi-Protocol Label              Switching (GMPLS) Signaling Functional Description",RFC3471, January 2003.   [RFC3473]  Berger, L., Ed., "Generalized Multi-Protocol Label              Switching (GMPLS) Signaling Resource ReserVation              Protocol-Traffic Engineering (RSVP-TE) Extensions",RFC3473, 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 2009Authors' 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.comCaviglia, et al.             Informational                     [Page 11]