Network management: Emerging trends and challenges

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<ul><li><p>Bell Labs Technical Journal OctoberDecember 1999 3</p><p>IntroductionBell Labs has played a historical role in bringing</p><p>reliability and dependability to the telecommunica-</p><p>tions infrastructure of the 20th century. A key compo-</p><p>nent of this possibly unique capability is an</p><p>understanding of the systems employed to manage</p><p>these networks and services. The current challenge</p><p>facing Bell Labs is to effectively harness this expertise</p><p>to bring public switched telephone network (PSTN)-</p><p>level reliability and dependability to data networks</p><p>and services of today and tomorrow. This issue of the</p><p>Bell Labs Technical Journal is devoted to bringing wide</p><p>exposure to the ongoing work in network management</p><p>in Bell Labs and Lucent Technologies business units. </p><p>This paper is organized as follows. In the section</p><p>immediately below, we describe the evolution of net-</p><p>work management and the role of network manage-</p><p>ment functions. The section following it provides the</p><p>key components of a network management system</p><p>(NMS) and lays a foundation for understanding the</p><p>papers in the issue. The next section, The Network</p><p>Environment: Then, Now, and in the Future, pre-</p><p>sents an overview of the current trends in networking</p><p>and services that have strong implications for the</p><p>requirements of a management system. Subsequently,</p><p>A Practical Vision for Managing Networks delves</p><p>into the management requirements induced by the</p><p>networking trends mentioned in the previous section</p><p>and thereby motivates the work described in this</p><p>issue. The last major section, A Snapshot of Trends</p><p>and Techniques, provides a short summary of the</p><p>papers in this issue.</p><p>Evolution of Network ManagementTelecommunication and services are in the</p><p>process of revolutionary yet evolutionary changes due</p><p>to transformation of the regulatory environment that</p><p>in turn has given rise to rapid improvements in the</p><p>underlying application, networking, computing, and</p><p> Network Management: Emerging Trends andChallengesShervin Erfani, Victor B. Lawrence, Manu Malek, and Binay Sugla</p><p>Network management is arguably one of the most important challenges faced bythe owners and operators of advanced networks and services. Lucent Technologies,as a major equipment vendor, and Bell Labs, as its R&amp;D arm, have had extensive his-torical experience with designing network management systems for AT&amp;T telecom-munication networks and other associated data networks. This experience enablesLucent to provide unique differentiation to its products and also places it in an excel-lent position to address the network management needs and challenges of theemerging networks and services. This issue of the Bell Labs Technical Journal pro-vides a sample of some of the many the activities, tools, technology trends, anddesigns currently under way in network management in various wings of Lucent.This paper, an introduction to the issue, discusses the evolution of network manage-ment, placing it in the context of underlying networking trends. In addition, it pro-vides a brief introduction to the papers presented in this issue, which togetherprovide a snapshot of Lucents network management activities in support of an efficient, reliable, and flexible networking vision. </p><p>Copyright 1999. Lucent Technologies Inc.. All Rights Reserved.</p></li><li><p>4 Bell Labs Technical Journal u OctoberDecember 1999</p><p>transmission technologies. Lucent is supplying service</p><p>providers with a variety of switching and transport</p><p>technologies capable of delivering voice and high-</p><p>speed data services. With these changes, network</p><p>operators will soon require next-generation network</p><p>management applications that deliver rich automated</p><p>functionality capable of responding at high speeds, yet</p><p>flexible enough to rapidly accommodate services that</p><p>will be introduced.</p><p>The purpose of network management is the</p><p>assignment and control of proper network resources,</p><p>both hardware and software, to address service perfor-</p><p>mance needs and the networks objectives. With the</p><p>ever-increasing size and complexity of underlying net-</p><p>works and services, it has become impossible to carry</p><p>out these functions without the support of automated</p><p>tools. The progress in network management reflects</p><p>the needs driven by these trends.</p><p>The evolution of network management is shown</p><p>in Figure 1. Prior to the 1980s, network management</p><p>was largely proprietary and, due to high development</p><p>costs, it was considered affordable by only a few very</p><p>large telecommunication carriers. Several develop-</p><p>ments in the 1980s caused a significant diffusion of</p><p>Panel 1. Abbreviations, Acronyms, and Terms</p><p>AALATM adaptation layerADSLasymmetric DSLATMasynchronous transfer modeB-ISDNbroadband ISDNCATVcommunity antenna televisionCIMcommon information modelCMIPcommon management information protocolCMISEcommon management information </p><p>service elementCORBA*Common Object Request Broker</p><p>ArchitectureDENdirectory enabled networkDiffServdifferentiated servicesDSLdigital subscriber lineDMTFDistributed Management Task ForceDWDMdense wavelength division multiplexingEMSelement management systemFCAPSfault, configuration, accounting, </p><p>performance, and securityGDMOguidelines for the definition of managed</p><p>objectsHDSLhigh bit-rate DSLHFChybrid fiber coaxIDLInterface Definition Language*IETFInternet Engineering Task ForceIPInternet protocolISDNintegrated services digital networkITSInternet telephony serverITU-TInternational Telecommunication Union</p><p>Telecommunication Standardization SectorLANlocal area networkLDAPlightweight directory access protocolMCNmanagement communications networkMIBmanagement information base</p><p>MPLSmultiprotocol label switchingMUXmultiplexerNMSnetwork management systemNMSnetwork management systemNNInetwork-to-network interfaceOAM&amp;Poperations, administration, </p><p>maintenance, and provisioningONUoptical network unitORBobject request brokerOSoperations systemPONpassive optical networkPOTSplain old telephone servicePSTNpublic switched telephone networkQoSquality of serviceRFCRequest for CommentsRMONremote monitoringRSVPresource reservation protocolRTPreal time protocolSDHsynchronous digital hierarchySLAservice level agreementSMIstructure of management informationSMKshared management knowledgeSMONswitch monitoringSNMPsimple network management protocolSONETsynchronous optical networkSS7Signaling System 7STMsynchronous transfer modeSVCswitched virtual circuitTCPtransfer control protocolTDMtime division multiplexed/multiplexingTDMtime division multiplexing/multiplexedUDPuser datagram protocolVDSLvery high bit-rate DSLxDSLany of various DSL modem technologies</p></li><li><p>Bell Labs Technical Journal u OctoberDecember 1999 5</p><p>network management technologies. Standards like</p><p>simple network management protocol (SNMP)1 and</p><p>common management information protocol</p><p>(CMIP)/common management information service</p><p>element (CMISE)2,3 paved the way for a standardized</p><p>method of communicating with the managed network</p><p>elements, while platforms like OpenView* obviated</p><p>the need to develop several core custom modules</p><p>required in a network management system. By imple-</p><p>menting a suite of integrated common software mod-</p><p>ules for topology discovery, map manipulation, drill-</p><p>down viewing, and database support, these platforms</p><p>reduced the cost of owning a network management</p><p>system by an order of magnitude. However, the man-</p><p>agement functionality still remained in its primitive</p><p>form, requiring network managers to observe and</p><p>interpret raw variables manually. Given the number of</p><p>variables per managed element and the typically large</p><p>number of managed elements, there was a driving</p><p>need for tools that provided higher levels of function-</p><p>ality at higher levels of abstraction.</p><p>Thus, the decade of the 1990s has been devoted to</p><p>the realization that the only feasible way to manage</p><p>large and increasingly complex networks is to devise</p><p>innovative management applications for all aspects of</p><p>management. Consequently, a number of automated</p><p>management applications that perform advanced</p><p>monitoring functions and attempt to provide an end-</p><p>to-end network-service-level view of the network</p><p>have been built. However, management at the net-</p><p>work level is still insufficient, and there is a strong</p><p>need to design and implement management applica-</p><p>tions that address the service level. The current focus</p><p>on service level agreements (SLAs) is a precursor to</p><p>this trend. (It may be noted that the AT&amp;T long dis-</p><p>tance telephony network that was supported by Bell</p><p>Labs had managed applications that operated at the</p><p>service level and performed both monitoring and</p><p>management applications that required control of the</p><p>network elements. However, these applications were</p><p>proprietary and assumed a single vendor solution.) </p><p>The general lack of effective, automated manage-</p><p>ment applications has given rise to an important and</p><p>fast-growing business opportunitynetwork manage-</p><p>ment service providers, like Lucents NetcareNetwork Management Services.4 These network man-</p><p>Proprietary,element</p><p>management</p><p>SNMP enabled,network</p><p>management</p><p>Servicemanagement</p><p>Manual</p><p>Monitoringonly</p><p>Control</p><p>19791988</p><p>19891998</p><p>19992008</p><p>SNMP Simple network management protocol</p><p>Figure 1. Evolution of network management.</p></li><li><p>6 Bell Labs Technical Journal u OctoberDecember 1999</p><p>agement service providers serve a very useful function</p><p>of offloading management tasks from enterprises and</p><p>network providers who either lack the skilled staff to</p><p>manage their own networks or would like to reduce</p><p>the cost of management.</p><p>Network Management FunctionsThough this issue of the Bell Labs Technical Journal</p><p>takes a broader, more popular view of the meaning of</p><p>the term network management to include aspects of ele-</p><p>ment and service management, network management</p><p>is, strictly speaking, only one layer of the management</p><p>systems hierarchy.</p><p>Figure 2 shows this hierarchical, layered</p><p>approach for partitioning and organizing management</p><p>activities and tasks, which is aligned with management</p><p>processes.5 The layers recognize that the management</p><p>of a telecommunications network service provider</p><p>must deal with network elements, networks, services,</p><p>and business issues. These five layers from the top</p><p>down are:</p><p> Business management layer,</p><p> Service management layer,</p><p> Network management layer,</p><p> Element management layer, and</p><p> Network element layer.</p><p>The layers are logical; they do not need to corre-</p><p>late with any physical implementation. The organiza-</p><p>tion of management tasks is service-based in the sense</p><p>that it will allow a specific service-management-layer</p><p>item to become traceable to its corresponding</p><p>required tasks at the network management layer all</p><p>the way down to the network element layer. The phi-</p><p>losophy is that the business requirements are the dri-</p><p>vers for all management issues. A particular business</p><p>goal dictates a specific set of requirements on the</p><p>underlying service management layer, which in turn</p><p>dictates the requirements for integration and interop-</p><p>erability on the underlying network management</p><p>layer. At the lower layers, activities affect physical</p><p>resources; at the higher layers, they affect relatively</p><p>abstract entities and processes like SLAs. Thus, imple-</p><p>mentation occurs in the reverse order. The upper four</p><p>layers distinguish management functions. The lowest</p><p>layer (the network element layer) represents the</p><p>management view provided by the network resources</p><p>(either hardware or software).</p><p>Business management layer Goal setting, finance, budgeting Planning, product definition</p><p>Service management layer Customer contact and interface Quality of service Interaction between services</p><p>Network management layer Connectivity among nodes Network control and coordination Network statistical log and events</p><p>Element management layer Control of subsets of network elements Gateway access to network elements Maintenance of statistical log and events</p><p>Network element layer Implementation of management commands Detection of problems</p><p>Figure 2. Network management layers.</p></li><li><p>Bell Labs Technical Journal u OctoberDecember 1999 7</p><p>Similarly, the required tasks of each management</p><p>layer can be categorized into the following five man-</p><p>agement functional areas: fault, configuration, account-</p><p>ing, performance, and security (FCAPS).6 These</p><p>management areas distinguish functions by the kinds</p><p>of activities they perform. The management functional</p><p>areas and organizational layers are orthogonal (mutu-</p><p>ally independent) classification schemes. For example,</p><p>fault management, when applied to the network man-</p><p>agement layer, includes the functions that deal with</p><p>analysis of alarms from all the network elements</p><p>within a given network in order to localize the fault</p><p>when functions at the element management layer</p><p>have been unable to do so within a particular network</p><p>element and/or limited subnet of network elements.</p><p>In practice, there can be many element manage-</p><p>ment systems (EMSs) and network management sys-</p><p>tems (NMSs) for implementing management</p><p>functions in each layer, which communicate with</p><p>functions in other layerstypically the layers directly</p><p>above or below the layer in question. The EMSs and</p><p>NMSs manage a set of network elements or a subnet,</p><p>respectivelythat is, a domain, may have inter-domain</p><p>communications.</p><p>The characteristics of inter-layer communications</p><p>between management functions are:</p><p> Lower layers are managed by upper layers.</p><p> Each layer manages multiple occurrences of</p><p>the layer directly below.</p><p> Each layer uses network management func-</p><p>tions/services of lower layers.</p><p> An FCAPS application in a layer may communi-</p><p>cate with other FCAPS applications in the same</p><p>layer (for example, synchronous optical net-</p><p>work (SONET) applications may talk to asyn-</p><p>chronous transfer mode (ATM) applications).</p><p>This architectural picture has been hard to trans-</p><p>late in practice due to the inherent technical difficulties</p><p>and costs of development.</p><p>Key Components of a Network ManagementSystem</p><p>The key constituents of a network management</p><p>system are best understood by considering the relation-</p><p>ship between the manager and the management agent</p><p>residing on the management element, as shown in</p><p>Figure 3. Given the diversity of managed elements like</p><p>servers, routers, switches, and the wide variety of oper-</p><p>Application</p><p>Instrumentation</p><p>Processing</p><p>Accessibleinformation</p><p>(MIB)Agent</p><p>Local managementand control</p><p>Access mechanismsand protocols(SNMP/CMIP)</p><p>Dataprocessing</p><p>Userinterface,graphics,</p><p>andvisualization</p><p>Interpretationand models</p><p>Managed element Manager</p><p>CMIP Common management information protocolMIB Management information baseSNMP Simple network management protocol</p><p>Figure 3. Manager-agent model.</p></li><li><p>8 Bell Labs Technical Journal u OctoberDecember 1999</p><p>ating systems and programming interfaces, it is critical</p><p>that the manager be able to communicate in a mean-</p><p>ingful way with the managed element. This is done via</p><p>the notion of an agent that not only can understand</p><p>the communication protocol, but also can organize</p><p>information in a consistent way so that both the man-</p><p>ager and agent can refer to the same informational</p><p>entity without ambiguity. Standardized communica-</p><p>tion protocols like SNMP or CMIP/CM...</p></li></ul>