MPLS Working Group Greg Jones (Ed) Internet Draft On behalf of the ITU-T TSB Intended status: Informational Expires: December 15, 2011 June 15, 2011 Assignment of an Associated Channel Type for Packet Transport Network Applications draft-tsb-mpls-tp-ach-ptn-01.txt Abstract The Transport Profile of Multi-Protocol Label Switching (MPLS- TP) is a packet-based transport technology based on the MPLS Traffic Engineering (MPLS-TE) and Pseudowire (PW) data plane architectures applicable in various deployment environments. This document describes the allocation of an Associated Channel Type to support ITU-T defined functions for packet transport network (PTN) applications, such as Operations, Administration and Maintenance (OAM), and applicable to MPLS-TP Pseudowires (PWs), Label Switched Paths (LSPs), Sub-path Maintenance Elements (SPMEs) and Sections. This document is intended to become a product of a joint Internet Engineering Task Force (IETF) / International Telecommunications Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network as defined by the ITU-T. Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and 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. ITU-T TSB Expires December 15 30, 2011 [Page 1] Internet-Draft ACH codepoint for PTN June 2011 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. 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. ITU-T TSB Expires December 15, 2011 [Page 2] Internet-Draft ACH codepoint for PTN June 2011 Table of Contents 1. Introduction...................................................4 1.1. PTN Application Description...............................5 1.2. Support for multiple applications.........................6 2. Conventions used in this document..............................6 2.1. Terminology...............................................7 2.2. Definitions...............................................7 3. Usage of the Associated Channel Type allocated for PTN.........7 4. Compatibility Considerations...................................7 5. Interconnection of PTN and PSN networks........................8 5.1. PTN client over a PSN server..............................8 5.2. PSN client over a PTN server..............................8 5.3. LSP or PW originating in a PTN network and terminating in a PSN network....................................................9 6. Security Considerations.......................................10 7. IANA Considerations...........................................10 8. Acknowledgments...............................................10 9. References....................................................11 9.1. Normative References.....................................11 ITU-T TSB Expires December 15, 2011 [Page 3] Internet-Draft ACH codepoint for PTN June 2011 Editors' Note: This Informational Internet-Draft is aimed at achieving IETF Consensus before publication as an RFC and will be subject to an IETF Last Call. [RFC Editor, please remove this note before publication as an RFC and insert the correct Streams Boilerplate to indicate that the published RFC has IETF Consensus.] 1. Introduction As noted in the multi-protocol label switching (MPLS-TP) Framework RFCs (RFC 5921 [5] and [6]), MPLS-TP is a packet-based transport technology based on the MPLS Traffic Engineering (MPLS-TE) and Pseudo Wire (PW) data plane architectures defined in RFC 3031 [1], RFC 3985 [2] and RFC 5659 [3] applicable in any packet network context. A subset of MPLS-TP is also applicable to ITU-T-defined packet transport networks (PTN), where the transport network operational model is deemed attractive. When MPLS-TP is deployed in PTN environment, application specific mechanisms (e.g., OAM) are required to allow service providers retaining the same operational experience in the MPLS- TP network as they had in their existing Synchronous Optical Network/Synchronous Digital Hierarchy (SONET/SDH) and Optical Transport Network (OTN) networks. When MPLS-TP is deployed in other environments, e.g. in a Packet Switched Network (PSN), application specific mechanisms (e.g., OAM) are required to allow service providers retaining the same operational experience in the MPLS-TP network as they had in their existing IP and MPLS networks. The standard MPLS-TP toolkit has to serve the interests of both communities of users. The standardization of the OAM toolset has not met the market needs of some PTN operators. Recognizing that it is very important for ITU-T and IETF to provide timely solutions to maintain support for the MPLS-TP agreements, the development of PTN application specific functions within ITU-T will allow ITU-T to satisfy the urgent needs expressed at the June 2010 Study Group 15 meeting. ITU-T TSB Expires December 15, 2011 [Page 4] Internet-Draft ACH codepoint for PTN June 2011 Allocation of one Associated Channel Type value will allow ITU-T to develop the tools required to address the unique needs of PTN application and will make more efficient use of the resources of both organizations while providing a mechanism to prevent the accidental interconnection between PTN and PSN application specific tools. The use of this code point fully complies with the framework and architecture for MPLS-TP. This document describes the allocation of an Associated Channel Type to support ITU-T defined functions for packet transport network applications, such as Operations, Administration and Maintenance (OAM), and applicable to MPLS-TP Pseudowires (PWs), Label Switched Paths (LSPs), Sub-path Maintenance Elements (SPMEs) and Sections. This document is intended to become a product of a joint Internet Engineering Task Force (IETF) / International Telecommunication Union Telecommunication Standardization Sector (ITU-T) effort to include an MPLS Transport Profile within the IETF MPLS and PWE3 architectures to support the capabilities and functionalities of a packet transport network as defined by the ITU-T. 1.1. PTN Application Description In this application MPLS-TP will be used to add packet transport capability to an existing circuit switched (SDH/OTN) transport network. A Transport Network is a connection oriented network that support transport paths that provides connectivity between service switches. Currently only point to point co-routed bidirectional transport paths are supported. It is expected that support for uni- directional point to point and uni-directional point to multipoint transport paths will be added in the future. A key characteristic for the transport network is the independence between services and transport i.e. the transport network is service agnostic. In the context of MPLS-TP the transport network provides a transport path for a PW or a LSP. Within a transport network multi technology transport nodes that support a combination of MPLS-TP, Ethernet, OTN and SDH transport technologies are typically deployed. Multiple transport layer networks may be supported by a common node. Note that in many existing transport networks, Ethernet technology has been already deployed to address some of the needs for packet transport capability. Ethernet is also a primary packet transport service for ITU-T TSB Expires December 15, 2011 [Page 5] Internet-Draft ACH codepoint for PTN June 2011 PTN. In this application, the primary requirements are driven by a desire for compatibility and consistency with the existing transport network operational behaviour, operational functionality and operational processes. In particular compatibility with the existing OAM and protection switching paradigm for SDH, OTN, Ethernet (i.e., provide the same controls and indications). Compatibility (consistency) means that the same management information model is used. This enables upgrades of the OSS infra structure in which it is only necessary to recognize the new type of layer network technology. It is also important to minimize the impact on the workforce that operates the existing transport network (e.g., the retraining required to add MPLS-TP to a network should be about the same as the retraining required when OTN is added to an SDH network). 1.2. Support for multiple applications Multiple applications are commonly supported from a single toolkit within the MPLS suite of protocols, with extensions that are applied to specific applications. As a consequence, the MPLS architecture allows multiple protocols to perform the same function for different network applications; e.g. o Three different label distribution protocols (LDP, RSVP-TE, BGP) o Two different routing protocols (OSPF-TE and ISIS-TE) o Three different VCCV types For any given application, a subset of protocols are implemented; e.g., o LDP is used for connectionless MPLS, o RSVP-TE is used for connection-oriented MPLS o BGP is used with L2 and L3 VPNs There are no MPLS architecture barriers to allowing different protocols for network operations in "PTN" and "PSN" applications while the operational requirement in these two applications domains are sufficiently distinct to justify such an approach. ITU-T TSB Expires December 15, 2011 [Page 6] Internet-Draft ACH codepoint for PTN June 2011 2. Conventions used in this document 2.1. Terminology G-ACh Generalized Associate Channel LSP Label Switched Path OAM Operations, Administration and Maintenance OTN Optical Transport Network PSN Packet Switched Network PTN Packet Transport Network PW Pseudowire SDH Synchronous Digital Hierarchy SONET Synchronous Optical Network SPME Sub-path Maintenance Element 2.2. Definitions This document uses the term LSP to indicate either a service LSP or a transport LSP (as defined in RFC 5921 [5]). This document uses the terms Section and Sub Path Maintenance Element (SPME) as defined in RFC 5921 [5]. 3. Usage of the Associated Channel Type allocated for PTN The usage of the associated channel type allocated for PTN applications will fully comply with the MPLS-TP data plane architecture and framework as described in RFC 5960 [7], RFC 5586 [4], RFC 5921 [5] and RFC 6215 [6]. 4. Compatibility Considerations As described in section 5 of RFC 5586 [4], an LER, LSR or PE that are not capable to processing packets on the Associated Channel Type allocated for PTN applications discards such packets when all the MPLS or PW labels have been popped. ITU-T TSB Expires December 15, 2011 [Page 7] Internet-Draft ACH codepoint for PTN June 2011 5. Interconnection of PTN and PSN networks PTN and PSN networks can be interconnected together. Three scenarios for interconnection are described in this section. 5.1. PTN client over a PSN server In this case a LSP originates and terminates in a PTN network and crosses a PSN network. The end to end PTN LSP runs as a client over the PSN network. In this case the PSN network must provide an appropriate class of service for the PTN LSP, e.g. it should use MPLS-TP or MPLS-TE. This is illustrated in Figure 1 below. ----------- ----------- ----------- / \ / \ / \ | PTN A |+++++| PSN B |+++++| PTN C | \ / \ / \ / ----------- ----------- ----------- PTN OAM |<------------...........................------------>| PTN OAM PSN OAM PTN OAM |<----------->| |<----------->| |<----------->| Section OAM Section OAM |<--->| |<--->| Figure 1 Interconnection case 1) PTN client over a PSN server Support of a PTN MIP within the PSN network is optional. Support of PTN alarm and lock reporting within the PSN network is optional. 5.2. PSN client over a PTN server In this case a LSP originates and terminates in a PSN network and crosses a PTN network. The end to end PSN LSP runs as a client over the PTN network. This is illustrated in Figure 2 below. ITU-T TSB Expires December 15, 2011 [Page 8] Internet-Draft ACH codepoint for PTN June 2011 ----------- ----------- ----------- / \ / \ / \ | PSN A |+++++| PTN B |+++++| PSN C | \ / \ / \ / ----------- ----------- ----------- PSN OAM |<------------...........................------------>| PSN OAM PTN OAM PSN OAM |<----------->| |<----------->| |<----------->| Section OAM Section OAM |<--->| |<--->| Figure 2 Interconnection case 2) PSN client over a PTN server Support of a PSN MIP within the PTN network is optional. Support of PSN alarm and lock reporting within the PTN network is optional. 5.3. LSP or PW originating in a PTN network and terminating in a PSN network In this case the PW (or LSP) originates (or terminates) in a PTN and terminates (or originates) in a PSN. The default OAM for the end to end LSP or PW is PSN. PTN OAM may be used if the network operators mutually agree to select this option. The default option is illustrated in Figure 3 below. ----------- ----------- / \ / \ | PTN A |+++++| PSN B | \ / \ / ----------- ----------- PSN OAM |<------------------------------->| PTN OAM PSN OAM |<----------->| |<----------->| Section OAM |<--->| Figure 3 Interconnection case 3) PTN to PSN ITU-T TSB Expires December 15, 2011 [Page 9] Internet-Draft ACH codepoint for PTN June 2011 In this case the PTN network is required to support PSN OAM for the termination or origination of an end to end LSP or PW. Support of the PSN MIP function in the PTN network is optional. 6. Security Considerations The security considerations for the generalized associate channel (G-ACh) are describes in RFC 5586 [4]. 7. IANA Considerations This document requires a unique Associated Channel Type which are assigned by IANA from the Pseudowire Associated Channel Types Registry. Registry: Value Description TLV Follows Reference ----------- ----------------------- ----------- --------- 0xXXXX PTN Applications (ITU-T) No (This Document) 8. Acknowledgments This document was prepared using 2-Word-v2.0.template.dot. ITU-T TSB Expires December 15, 2011 [Page 10] Internet-Draft ACH codepoint for PTN June 2011 9. References 9.1. Normative References [1] Rosen, E., Viswanathan, A., Callon, R., "Multiprotocol Label Switching Architecture", RFC 3031, January 2001 [2] Bryant, S., Pate, P., "Pseudo Wire Emulation Edge-to-Edge (PWE3) Architecture", RFC 3985, March 2005 [3] Bocci, M., Bryant, S., "An Architecture for Multi-Segment Pseudo Wire Emulation Edge-to-Edge", RFC 5659, October 2009 [4] Vigoureux, M., Bocci, M., Swallow, G., Ward, D., Aggarwal, R., "MPLS Generic Associated Channel", RFC 5586, June 2009 [5] Bocci, M., Bryant, S., Frost, D., Levrau, L., Berger, L., "A Framework for MPLS in Transport Networks", RFC 5921, July 2010 [6] Bocci, M., et al., " MPLS Transport Profile User-to-Network and Network-to-Network Interfaces", RFC 6215, April 2011 [7] Frost, D., Bryant, S., Bocci, M., "MPLS Transport Profile Data Plane Architecture", RFC 5960, August 2010 Authors' Addresses Greg Jones (Editor) ITU-T TSB Email: Greg.Jones@itu.int International Telecommunication Union (ITU) Telecommunication Standardization Bureau (TSB) Email: tsbsg15@itu.int ITU-T TSB Expires December 15, 2011 [Page 11]