draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 Network Working Group Internet Draft Diego Caviglia Intended Status: Informational Dino Bramanti Ericsson Dan Li Huawei Document: draft-caviglia-ccamp-pc-and-sc-reqs-01.txt Expires: December 2006 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 applicable patent or other IPR claims of which he or she is aware have been or will be disclosed, and any of which he or she becomes aware will be disclosed, in accordance with Section 6 of BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http://www.ietf.org/ietf/1id-abstracts.txt The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. 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. Caviglia et al. Expires - December 2006 [Page 1]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 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", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119 [1]. Table of Contents 1 Introduction...................................................3 1.1 Label Switched Path Terminology.............................3 1.2 LSP within GMPLS Control Plane..............................4 1.3 Resource Ownership..........................................4 1.4 Migration to GMPLS Control..................................4 2 Typical Use Cases..............................................5 2.1 PC to SC Conversion.........................................5 2.2 SC to PC Conversion.........................................5 3 Problem Explanation............................................6 4 Requirements...................................................7 4.1 Data Plane LSP Consistency..................................7 4.2 No Disruption of User Traffic...............................7 4.3 Transfer from Management Plane to Control Plane.............7 4.4 Transfer from Control Plane to Management Plane.............7 4.5 Synchronization of state among nodes during migration.......7 4.6 Support of Soft Permanent Connections.......................7 4.7 Failure of Transfer.........................................7 4.8 Backward Compatibility......................................7 4.9 Re-Use of Protocol Mechanisms...............................8 5 Security Considerations........................................8 6 IANA Consideration.............................................8 7 References.....................................................8 7.1 Normative References........................................8 7.2 Informative References......................................8 8 Acknowledgments................................................8 Caviglia et al. Expires - December 2006 [Page 2]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 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 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 and is the end-to-end connection. In the Management Plane, an LSP is the state information associated with and necessary for the creation and maintenance of a Data Plane connection. In the Control Plane, an LSP is the state information 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 length. Caviglia et al. Expires - December 2006 [Page 3]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 1.2 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. 1.3 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 as a controlling interest in the resource. Consider, for 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. 1.4 Migration to GMPLS Control The deployment 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. Caviglia et al. Expires - December 2006 [Page 4]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 It is also desirable to migrate 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. Where such connections are in service, such migration must be performed in a way that does not affect traffic. Since attempts to migrate to GMPLS control might fail it is also advisable 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 (PC to SC, PC to SPC, and SPC to SC). So the reverse mappings are also needed (SC to PC, SC to SPC, and SPC to PC). 2 Typical Use Cases 2.1 PC to SC Conversion A typical scenario where a "PC to 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 are already set up as PCs and are owned by the Management Plane. As part of a migration strategy another similar scenario will arise when a network is partially controlled by the Management Plane and partially controlled by the Control Plane (PCs and SCs coexist), and an upgrade or coverage extension of the Control Plane is required. In both cases, a connection, set up and owned by the Management Plane, may need to be transferred to Control Plane control. Where the connection is carrying traffic, this transfer has to be done without any disruption to the Data Plane traffic. 2.2 SC to PC Conversion An example of a scenario where the "SPC to PC" procedure may be used is when a Control Plane failure happens in a certain area of the network, and the ability of the Control Plane to control the connections is partially lost. In such a case, according to the configured policy at each node, the Data Plane connections which are owned by the Control Plane could be smoothly switched over to Management Plane. Again there is a requirement that this is achieved without any interference to the associated Data Plane state so that the connection continues to be operational and to carry traffic during the transition. Caviglia et al. Expires - December 2006 [Page 5]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 3 Problem Explanation Having the ownership of an LSP means having ownership of the resources used by the LSP as defined in section 1.2. In general when the Management Plane has ownership of an LSP the Control Plane cannot see the LSP and cannot exert control over the resources used by the LSP. Depending on implementation, any attempt by the Control Plane to exert control over the resources will fail. For example, an attempt to set up a new LSP within the Control Plane that uses a resource owned by the Management Plane will fail. In general, when the Control Plane has ownership of an LSP the Management Plane has restricted control over the resources used by the LSP. The Management Plane may be able to see the Control Plane LSP (in fact, this is one of the objectives of a Management Plane), but the Management Plane cannot provision a new LSP that uses the resources in use for the Control Plane LSP. As described in section 1.2, the Management Plane may have some direct control over the resources in use for Control Plane controlled LSPs (for example, for safety reasons), but this does not alter the basic ownership property of those resources. It is always the case that the Management and Control Planes cannot directly change each other's LSP state. Therefore, in order to transfer the ownership of an LSP from one plane to another, it is not simply enough to initiate the normal procedures for setting up an LSP in the plane that is taking over. For example, if an attempt is made for the Control Plane to take over a Management Plane LSP by the use of normal signaling messages then there are two possibilities. - If the signaling messages do not specify the precise Data Plane resources to be used, a new LSP will be established in the Data Plane using different resources from those in use by the Management Plane LSP. This is not the objective since such a procedure would require the data to be switched to the new LSP which might involve interruption to the traffic. Further, the network may be sufficiently resource constrained that such a process is impossible. - If the signaling messages specify the precise resources to use in order to ensure that the new Control Plane LSP will use the same resources as the Management Plane LSP, then the Control Plane LSP will fail to set up because the resources are already in use and owned by the Management Plane. Clearly some new procedures and protocol extensions are needed to enable this simple function. Caviglia et al. Expires - December 2006 [Page 6]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 4 Requirements This section sets out the basic requirements for procedures and processes that are used to perform the functions described in this document. 4.1 Data Plane LSP Consistency The Data Plane LSP in place before and after the transfer process MUST follow the same path through the network and MUST use the same network resources. 4.2 No Disruption of User Traffic The transfer process MUST NOT cause any disruption of user traffic on the LSP being transferred or any other LSP in the network. 4.3 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 4.4 Transfer from Control Plane to Management Plane It MUST be possible to transfer the ownership of an LSP from the Control Plane to the Management Plane. 4.5 Synchronization of state among nodes during migration It MUST be assured that the state of the LSP is synchronized among all nodes traversed by it before proceeding to the migration. 4.6 Support of Soft Permanent Connections It MUST be possible to segment an LSP such that it is converted to or from an SPC. 4.7 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. 4.8 Backward Compatibility Any new procedures and protocol extensions MUST be fully backward compatible. This means that should any LSR on the path of an LSP be unable to handle the new procedures or protocol extensions the design of the procedures and specification of the extensions MUST be Caviglia et al. Expires - December 2006 [Page 7]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 such that a transfer failure automatically occurs and the ownership remains unchanged. 4.9 Re-Use of Protocol Mechanisms Any new procedures or protocol extensions SHOULD make use of existing procedures and protocol objects where possible. 5 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 intervention. 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. 6 IANA Consideration This requirement document makes no requests for IANA action. 7 References 7.1 Normative References [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997 7.2 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 8 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 and Vijay Pandian for their suggestions and comments on the CCAMP list. Caviglia et al. Expires - December 2006 [Page 8]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 9 Authors' Addresses Diego Caviglia Marconi Via A. Negrone 1/A Genova-Sestri Ponente, Italy Phone: +390106003738 Email: diego.caviglia@marconi.com Dino Bramanti Marconi Via Moruzzi 1 C/O Area Ricerca CNR Pisa, Italy Email: dino.bramanti@marconi.com Nicola Ciulli NextWorks Corso Italia 116 56125 Pisa, Italy Email: n.ciulli@nextworks.it Dan Li Huawei Technologies Co., LTD. Huawei Base, Bantian, Longgang, Shenzhen 518129 P.R.China danli@huawei.com Tel: +86-755-28972910 Han Li China Mobile Communications Co. 53A Xibianmennei Ave. Xuanwu District Beijing 100053 P.R. China lihan@chinamobile.com Tel: +86-10-66006688 ext. 3092 Intellectual Property Rights Notices 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 Caviglia et al. Expires - December 2006 [Page 9]
draft-caviglia-ccamp-pc-and-sc-reqs-01.txt June 2006 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 rights that may cover technology that may be required to implement this standard. Please address the information to the IETF at ietf- ipr@ietf.org. Full Copyright Statement Copyright (C) The Internet Society (2006). 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. 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 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. Caviglia et al. Expires - December 2006 [Page 10]