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    Mplstp whitepaper Mplstp whitepaper Document Transcript

    • MPLS Evolution: MPLS Abstract: In recent years, market forces in the telecommunicationTransport Profile industry have been pulling from several directions. There is an emerging need for packet-oriented aggregation infrastructures complementing the traditional SONET/SDH transport solutions with equivalent operationalAuthor characteristics. To serve the need, in 2006, ITU-T came up with MPLS based T-MPLS protocol, but due to compatibilityAnkur Rawat, issues with MPLS, T-MPLS was terminated at a very early age. In 2008, ITU-T joined hands with IETF to develop a protocol called MPLS-TP. This protocol was extension of T-Sasindran M Prabhu MPLS with compatibility issues resolved. This paper provides an overview of MPLS-TP, differences14th May, 2010 between MPLS-TP and T-MPLS, OAM frame structure of MPLS-TP and market prospects of MPLS-TP. Also, this paper outlines Tech Mahindra’s approach towards this protocol. © Tech Mahindra Limited 2010
    • Table of ContentsIntroduction to MPLS, T-MPLS & MPLS-TP .....................................................................................1 Acronyms & Abbreviations ...............................................................................................................3 MPLS-TP Characteristic features & Advantages .............................................................................4 OAM frame structure of MPLS-TP & T-MPLS ..................................................................................5 Functions of Associated Channel (ACH) ..........................................................................................6 Differences between T-MPLS and MPLS-TP ...................................................................................7 Market Prospects ..............................................................................................................................8 Summary ..........................................................................................................................................9 Tech Mahindra’s Plan .....................................................................................................................10 References .....................................................................................................................................11  © Tech Mahindra Limited 2010
    • Introduction to MPLS, T-MPLS & MPLS-TPStandardized by the IETF, IP/MPLS is a scalable, protocol designed to carry circuit and packettraffic over virtual circuits known as label switched paths (LSPs). Operating at an OSI layerbetween the traditional definitions of Layer 2 and Layer 3, IP/MPLS makes packet-forwardingdecisions based on the contents of the label.Standardized by ITU-T, Transport MPLS (T-MPLS) is a new formulation of MPLS, designedspecifically for application in transport networks. It builds upon well known and widely deployedIP/MPLS technology. It offers a simpler implementation, where features not relevant toconnection-oriented applications are removed and critical transport functionality gaps areaddressed. Work to define T-MPLS was started by the ITU-T in February 2006. ITU-T ceasedwork on T-MPLS in December 2008, in favor of MPLS-TP standardization.IETF raised concerns over compatibility of T-MPLS with the already established IP/MPLS. Toaddress these concerns, In February 2008, the ITU-T and IETF joined hands to form a JointWorking Committee (JWC). JWC came up with a technical solution called MPLS Transport Profile(MPLS-TP). On one hand, MPLS-TP uses a subset of MPLS standards where features that are notrequired in transport networks such as IP forwarding, penultimate hop popping (PHP), or equalcost multiple paths (ECMP) are not supported or made optional. On the other hand, MPLS-TPdefines extensions to existing MPLS standards and introduces established requirements fromtransport networks.MPLS-TP has comprehensive set of OAM and protection features. OAM features help in fastdetection, localization, troubleshooting, SLA verification and performance monitoring.Protection functionality allows the transport grade sub-50 ms recovery for both linear and ringapplication. By providing an expansive set of OAM, recovery tools and NMS-based operation,MPLS-TP enables more deterministic network operation which allows quick detection andcorrection for any SLA violation. It gives the network operators full control of their networks.MPLS-TP has some optional features e.g., the control plane is optional and protocols such asOAM and protection are designed to operate fully without a control plane. Figure 1 and 2illustrates the set of overall functionalities of the MPLS-TP [3]. Figure 1: Basic functionalities of MPLS-TP 1 © Tech Mahindra Limited 2010
    • MPLS-TP introduces features associated with transport networks (such as data plane-basedOAM & protection switching, separation of control & data plane) and transport grade OAMfunctions. These features facilitate the transition to a connection-oriented packet transportnetwork by providing efficient packet switching while allowing transport-grade operations [3]. Figure 2: Additional functionalities of MPLS-TP2 © Tech Mahindra Limited 2010
    • Acronyms & AbbreviationsACH Associated ChannelAPS Automatic Protection SwitchingBoS Bottom of StackDCC Data Communication ChannelEXP ExperimentalG-ACH Generic Associated ChannelIETF Internet Engineering Task ForceITU-T International Telecommunication UnionLFU Label for YouLSP Label Switched PathMAC Media Access ControlMCC Management Communication ChannelMEG Maintenance Entity GroupMEL Maintenance Entity Group LevelMEP Management End PointMIP Management Intermediate PointMPLS Multi Protocol Label SwitchingMPLS-TP MPLS – Transport ProfileNMS Network Management SystemOAM Operation, Administration and MaintenancePW PsuedowireSCC Signaling Communication ChannelSONET Synchronous Optical NetworkSDH Synchronous Digital HierarchyTTL Time to LiveTMP T-MPLS MapT-MPLS Transport MPLSVCCV Virtual Circuit Connectivity Verification 3 © Tech Mahindra Limited 2010
    • MPLS-TP Characteristic features & AdvantagesMPLS-TP promises key enhancements to MPLS, such as engineered point-to-point bi-directionallabel switched paths (LSPs) and end-to-end LSP protection facilities. These features will providebenefits to Telecom Service Providers. Some of the key characteristics features & there benefitsare mentioned below.• Connection oriented protocol.• Meets functional requirements of service provider transport applications.• Interoperates with existing MPLS and pseudowire emulation edge-to-edge (PWE3) networks.• Consistent with MPLS architecture and forwarding paradigm, using a subset of the MPLS data plane and re-uses generic pseudowire (PW) and MPLS LSP constructs.• Enhanced OAM functionality.• OAM is able to trigger path recovery actions without control or management plane interaction.• Packet forwarding is not required to operate or configure the data plane, or to support OAM, and has no dependency on routing protocols.• Allows bi-directional, congruent (share same path through network), point-to-point LSPs.• Introduces the Generic Associated Channel, this channel can be used to send traffic as well as data.• Control plane is not mandatory for network operation. Provisioning (automated or manual) can be via network management system.4 © Tech Mahindra Limited 2010
    • OAM frame structure of MPLS-TP & T-MPLSThe OAM frame structure of MPLS-TP is different from that of T-MPLS. MPLS-TP uses theAssociated Channel (ACH) to identify the OAM frame. LSP ACH and PW ACH adopt the sameOAM mechanism. Figure 3 shows the OAM frame structure of T-MPLS. Figure 4 and Figure 5show the OAM frame structure of MPLS-TP LSP & PW respectively [1], [2]. Figure 3: OAM frame structure of T-MPLSMPLS-TP introduces Management End Point (MEP) and Management Intermediate Point (MIP),which allows for continuity checks and connectivity verification messages propagated betweenthe two end points. This works as a powerful tool for fast detection of lost connectivity as wellas support for connection mis-configuration. Figure 4: OAM frame structure of MPLS-TP LSPMPLS-TP OAM supports monitoring of the SLAs using continuity check and connectivityverification. In addition, it provides mechanism s for performance monitoring including delayand loss measurements to detect performance degradations. MPLS-TP OAM supports thecontrol of the alarm escalation process using alarm suppression, thereby enabling faults to bquickly detected and isolated, while avoiding unnecessary alarm storms in the network. Figure 5: OAM frame structure of MPLS-TP PW 5 © Tech Mahindra Limited 2010
    • Functions of Associated Channel (ACH)In order to ensure proper operational control, MPLS-TP network elements exchange OAMpackets that strictly follow the same path as traffic data (OAM in the data plane), with a commonset of tools running at each network level (PW, LSP, and section). OAM packets are carried usingthe Generic Associated Channel (G-ACh).The functions of Associated Channel are listed below:• Associated Channel is a generic function. It can run over LSP as well as PW.• Associated Channel allows the operator to send any type of control traffic into a PW or LSP. For example, Virtual Circuit Connectivity Verification (VCCV) may be sent over an associated channel to monitor if the PW is available.• Associated Channel is capable of carrying user traffic, OAM traffic & Management traffic. For example, associated channel can also carry Automatic Protection Switching (APS) information and Data Communications Channel (DCC), Signaling Communication Channel (SCC), and Management Communication Channel (MCC) management traffic, etc.6 © Tech Mahindra Limited 2010
    • Differences between T-MPLS and MPLS-TPOAM header and the interpretation of different fields inside the header form the base for the setof differences between T-MPLS & MPLS-TP.Some of the differences are listed below.• T-MPLS uses reserved “Label 14” as OAM identifier whereas MPLS-TP uses “Label 13” as OAM identifier.• T-MPLS uses the type of “+1” or “-1” values of MEL (Maintenance Entity Group Level) to indicate the nesting of OAM whereas MPLS-TP uses label stack to indicate nesting of OAM.• MPLS-TP uses Time-to-Live (TTL) to trace the MIP path and monitor the loopback status , while T-MPLS uses TTL in the OAM packet header label to identify Management Entity Group Intermediate Point (MIP): TTL=MIP hops+1, and MIP processes the OAM frames with MEL=0 and TTL=2. MPLS-TP uses TTL in the LSP or PW label only. 7 © Tech Mahindra Limited 2010
    • Market ProspectsIn the fixed-line network, the successful application of ADSL technology has brought a 2Mbpsbandwidth to the end user’s home. The increasing growth of broadband subscriber base resultsin huge demands for large bandwidth. Data traffic transferred through the provincial backbonetransport network accounts for 90% of the total traffic. This indicates that the IP-based servicebearing has become the development trend in the industry. The future service transportnetwork tends to be intelligent, highly integrated and broadband-enabled, which can beachieved by using the MPLS-IP technology.Leading network operators such as British Telecom (BT), France Telecom (FT) and China Mobilehave been actively participating in the MPLS-TP standardization and have planned to use theMPLS-TP technology for service transport and mobile data backhaul. They have been activelyparticipating in and paying much attention to the development and testing of related productsby telecom equipment manufacturers.Leading telecom equipment manufacturers, such as Alcatel-Lucent, Cisco, Nortel, Nokia-Siemens, Ericsson, ZTE, Huawei, FiberHome, UTStarcom, etc., have been actively involved in theR&D of the MPLS-TP technology and related standardization work. For example, ZTE hasimplemented MPLS-TP related OAM and protection functions on its ZXR10 9000 and ZXCTN6100/6200/6300 product series and successfully trialed them over the networks of operatorssuch as China Mobile and Telecom Malaysia. Huawei has launched the PTN 912/OSN 3900/1900series, FiberHome the CiTRANS 660/620 series, UTStarcom the TN 725/705 series, Alcatel-Lucent the 1850 TSS 320/40/5 series and Ericsson the OMS 2430/2450 series.On all accounts, both telecom equipment manufacturers and network operators have beenactively engaged in the research and planning of the MPLS-TP technology. This indicates thatMPLS-TP has promising prospects and will play a key role in the future packet transportnetwork.8 © Tech Mahindra Limited 2010
    • SummaryMPLS-TP represents an optimized combination of MPLS & transport networks, designed to carrypackets. It provides an evolution path from SONET/SDH based networks to packet networks. Itpreserves the advantageous features of SONET/SDH like OAM & protection switching, thusallowing the full end-to-end integration with existing MPLS infrastructure. By using MPLS-TP,Service providers will have the manageability, stability, flexibility, scalability and deterministicperformance in there network from edge to edge.With MPLS-TP, Service Providers will enjoy all of the following benefits. • Carrier grade, multi vendor, IETF/ITU-T standardized Common packet transport network. • Fully integrated IP and transport platform for next-generation common access and transport solution. • Support for end to end QoS, strict Committed Information Rate (CIR), guaranteed frame delay, frame delay variation and packet loss ratio. • Capability to obtain different performance characteristics for key applications without requiring the use and expense of multiple networks. • Support for sub 50ms protection switching ensuring high availability. • Comprehensive OAM functionality. 9 © Tech Mahindra Limited 2010
    • Tech Mahindra’s PlanBased on the Capabilities in MPLS, Optical Networks (SONET/SDH) and other data-communication technologies, Tech Mahindra will be able to contribute in the following areas.Based on the market potential and the opportunities from the vendors, we will be able to selecta few among these areas. • MPLS-TP Data plane module • MPLS-TP Control plane module • MPLS-TP OAM module • MPLS-TP EMS/NMS moduleBased on the opportunity from the vendors, we will be able to select among these activities: • Requirement Analysis • Product Design & Development • Testing & Validation • Interoperability Testing • Network Design, Deployment & Maintenance for Telecom Service Providers.10 © Tech Mahindra Limited 2010
    • References 1. http://wwwen.zte.com.cn/endata/magazine/ztecommunications/2009year/no1/articles /200903/t20090319_170886.html 2. http://www.ietf.org/MPLS-TP_overview-22.pdf 3. “MPLS-TP: The Key Enabler of Converged Packet Transport Networks” -Whitepaper by Alcatel-Lucent. 4. http://www.faqs.org/rfcs/rfc5317.html 5. http://www.cisco.com/en/US/technologies/tk436/tk428/white_paper_c11-562013.pdf 6. http://tools.ietf.org/pdf/draft-ietf-mpls-tp-oam-framework-06.pdf 7. http://en.wikipedia.org/wiki/T-MPLS 8. http://en.wikipedia.org/wiki/MPLS-TP 9. http://www.dfn.de/fileadmin/3Beratung/DFN-Forum2/118.pdf 11 © Tech Mahindra Limited 2010