Network work group Diego Caviglia Internet Draft Dino Bramanti Ericsson Dan Li Huawei Dave McDysan Verizon Intended Status: Informational Expires: August, 18 2008 February 18, 2008
August 3, 2007Requirements for the Conversion Between Permanent Connections and Switched Connections in a Generalized Multiprotocol Label Switching (GMPLS) Network draft-ietf-ccamp-pc-and-sc-reqs-01.txtdraft-ietf-ccamp-pc-and-sc-reqs-02.txt 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 This Internet-Draft will expire on February 3,August 18, 2008. 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. 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 [RFC 2119]. Table of Contents 1. Introduction.................................................3 2. Motivation...................................................3 3. Label Switched Path Terminology..............................4 4. LSP within GMPLS Control Plane...............................4 4.1. Resource Ownership......................................4 4.2. Setting Up a GMPLS Controlled Network...................5 5. Typical Use Cases............................................6 5.1. PC to SC/SPC Conversion.................................6 5.2. SC to PC Conversion.....................................7 6. Requirements.................................................7 6.1. Data Plane LSP Consistency..............................7 6.2. No Disruption of User Traffic...........................7 6.3. Transfer from Management Plane to Control Plane.........8 6.4. Transfer from Control Plane to Management Plane.........8 6.5. Synchronization of state among nodes during conversion..8 6.6. Support of Soft Permanent Connections...................8 6.7. Failure of Transfer.....................................8 7. Security Considerations......................................8 8. IANA Considerations..........................................9 9. References...................................................9 9.1. Normative References....................................9 9.2. Informative References..................................9 10. Acknowledgments.............................................9 11. Authors' Addresses.........................................10 12. Full Copyright Statement...................................11 13. Intellectual Property Statement............................11 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) [G.8081]. When the setup, teardown, and maintenance of connections are achieved by means of a signaling protocol owned by the Control Plane 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]. At least some control plane initiated aspects of a connection must be capable of being queried by the management plane. These aspects should be independent of how the connection was established. 2. Motivation The main motivation for this work is the LSP conversion from Management Plane PC to Control Plane SC. The objective is to be able to introduce a control plane into an existing network without disrupting user traffic. An example of this is an operator establishing PCs before the SC technology is mature, or SC interoperation is achieved between multiple implementations. 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, or desirable, feature. The requirement for LSP conversion from Control Plane to Management Plane should be scoped as a back-out procedure. A significant benefit of GMPLS in networks is discovering and validating the current state of the network. For example, an operator could invoke an SC, determine that the automatically discovered path is good and then "pin" a connection to this specific path using the SC to PC conversion procedures. This is attractive to network operators who prefer the static nature of the path for a PC as compared with the potentially dynamic path of an SC. 3. 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 connection. 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 length. In this document, when we talk about 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. 4. LSP within GMPLS Control Plane Generalized Multiprotocol Label Switching (GMPLS) [RFC 3471], [RFC 3473] 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 TDM (SDH/SONET G.709 at ODUk level) transport and WDM (G.709 OCh level). 4.1. 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 segment in the middle of the network). Note that the management plane assigns resources to the control plane. 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 e.g. the basic safety requirements that imply that management commands must be available to set laser out of service. 4.2. 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 a LSP under GMPLS control might fail due to a number of reasons outside the scope of this draft, it is also highly desirable to have a mechanism to convert the control of an LSP back to the Management Plane, in fact undoing the whole process for reasons summarized in the motivation section. 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 PC). Conversion to/from control/management will occur in many MIBs or network management data structures where the owner of the hop level information (e.g., cross-connect, label assignment, label stacking, etc.) is identified as either a specific control protocol, or manual (i.e., 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 and the state of the hop level information restored to that before the conversion was attempted, and an error condition 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 somehow indicate to each hop that a control protocol is now to be used, and then configure the data needed by control protocol at the connection endpoints. When converting from an SC to a PC, the management plane must change the owner of each hop. Somehow, then the instance in the control plane must be removed without affecting the data plane. This may best be done via a make before break operation. 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 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. 5. Typical Use Cases 5.1. 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 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. 5.2. 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 specified as mandatory in this document, but is still a highly desirable function. 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. 6. Requirements This section sets out the basic requirements for procedures and processes that are used to perform the functions this document is about. 6.1. 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. 6.2. 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. SC to PC conversion and vice-versa shall occur without generating management plane alarms toward the end users at neither the UNI endpoints nor the NMS. 6.3. 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 6.4. 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. 6.5. 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. 6.6. Support of Soft Permanent Connections It MUST be possible to segment an LSP such that it is converted to or from an SPC. 6.7. 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 Transport Network Elements (TNEs) 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 it is fully under control of the owning entity. 7. 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. If SNMP MIBs are used for configuration, then the management plane should support at least authentication for PC<>SC configuration changes as specified in [RFC 3414]. Note also that implementations may enable policy components to help determine whether individual LSPs may be transferred between planes. 8. IANA Considerations This requirement document makes no requests for IANA action. 9. References 9.1. Normative References [RFC 2119] Bradner, S., "Key words for use in RFCs to Indicate [G.8081] ITU-T, "Terms and definitions for Automatically Switched Optical Networks (ASON)," Recommendation G.8081/Y.1353, [RFC 3414] U. Blumenthal, B. Wijnen, "User-based Security Model(USM) for version 3 of the Simple Network Management Protocol (SNMPv3)," RFC 3414, December 2002 9.2. Informative References [RFC 3471] L. Berger (Ed.) "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Functional Description", RFC 3471, January 2003 [RFC 3473] L. Berger (Ed.) "Generalized Multi-Protocol Label Switching (GMPLS) Signaling Resource ReserVation Protocol-Traffic Engineering (RSVP-TE) Extensions", RFC 3473, January 2003 10. 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 list. 11. Authors' Addresses Diego Caviglia Ericsson Via A. Negrone 1/A Genova-Sestri Ponente, Italy Phone: +390106003738 Email: firstname.lastname@example.org@ericsson.com Dino Bramanti Ericsson Via Moruzzi 1 C/O Area Ricerca CNR Pisa, Italy Email: email@example.com@ericsson.com Nicola Ciulli NextWorks Corso Italia 116 56125 Pisa, Italy Email: firstname.lastname@example.org Dan Li Huawei Technologies Co., LTD. Huawei Base, Bantian, Longgang, Shenzhen 518129 P.R.Chin Phone: +86-755-28972910 Email: email@example.com Han Li China Mobile Communications Co. 53A Xibianmennei Ave. Xuanwu District Beijing 100053 P.R. China Phone: +86-10-66006688 ext.3092 Email: firstname.lastname@example.org Dave McDysan Verizon Ashburn, VA, USA Email: email@example.com 12. Full Copyright Statement Copyright (C) The IETF Trust (2007).(2008). 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, 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. 13. 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