Building Mission Critical NetworksAuthor’s PrefaceThe modern enterprise is challenged to do more with less. The enterprise mission has expanded as staff numbers have shrunk. Technology can help to achieve the enterprise goals, but only if it can be deployed in a flexible manner that fits with the organisation needs, culture and employee skills. “Mission Critical” in today’s enterprise means more than reliability. A mission critical network must empower the enterprise to achieve its mission now and in the future. The network must integrate historical investments, empower the current enterprise needs and provide a basis for the future development of the enterprise. Moreover, it must reach to the far corners of the enterprise and deliver to remote sites services equivalent to those experienced in enterprise headquarters. Today’s mission critical network is primarily about delivering services to enterprise employees anywhere and anytime. The enterprise will only be fully capable of meeting its mission in an unpredictable future when the network architecture is designed to deliver multiple services to many sites over a range of coordinated technologies. The multi technology, multi service network architecture can be built with some key building blocks suited to sites of varying sizes and served by varying wide area connections. This paper describes a mission critical network architecture that respects the past, lives in the present and serves for the future. Stewart Snell Contents
Building Mission Critical NetworksThe ProblemMore than ever, enterprises today rely on information technology and telecommunications to produce and deliver the goods and services that comprise the enterprise’s mission. Increasingly, fulfilling the enterprise’s mission requires use of advanced communications technology. Competition and cost pressures have turned enterprises towards out-sourcing of non-core functions and increasing reliance on automated systems. Modern enterprises can no longer fulfil their missions without a comprehensive, robust and cost effective whole of enterprise network. The modern enterprise is faced with a complex array of choices when developing its communications strategy for the whole of enterprise mission critical network. Technological change is rapid and difficult to predict. In the commercial sphere, traditional carriers are in the midst of rapid change and new carriers are emerging. Within the enterprise, new data and voice applications are changing both the internal operating environment and the enterprise’s relationships with its customers and suppliers. Many enterprises are evaluating, or implementing, electronic commerce solutions based on the Internet. Applications include on line publishing of product information, remote access to corporate information, exchange of electronic documents, and video distribution. Computer Telephony Integration (CTI) applications based on the Internet are also emerging. Increasingly, email is taking the place of internal telephone calls, company to company correspondence and facsimile traffic. Electronic commerce applications based on the Internet have been successful where previous attempts have failed (e.g. previous attempts based on the OSI model.) The success of the Internet has prompted some commentators to conclude that the Internet Protocol (IP) will replace all other protocols in a brave new IP world. At the same time, customer to enterprise communications are rapidly moving from a branch office model using letter post to intelligent telephony networks feeding into call centres and automated response systems. The twin impact of the Internet and intelligent telephony networks is to shift the balances of traffic between voice and data and between the enterprise and the outside world. Within the enterprise, voice traffic is being reduced as email traffic increases. Conversely, intelligent telephony networks increase the volume of customer voice traffic. Or, in some cases, moves the concentration point of traffic from branches to a central site. Data networks that were contained within the enterprise now have gateways to customers and suppliers. Where the enterprise network once reached out to the branches, it now attempts to reach all suppliers and potential customers. Within industrial sites, business management systems are increasingly being integrated with production process control to minimise production cost while smoothing inventory variations. Transmission between sites was once the province of the traditional carrier; increasingly it is now a choice between different carriers, or perhaps between different private technologies. Also, increasingly, the demand is for higher transmission bandwidth. Sites that were joined with low speed digital links now require 64 kbps. Sites that used 64 kbps links are migrating to n x 64 kbps. Higher speed alternatives are being sought to 2 Mbps links. Within sites, and over short haul links in cities, enterprises are examining links at 34 Mbps and even up to 155 Mbps. (Higher speeds than 155 Mbps are still the domain of carriers, or are quarantined by cost to within-building distances). The enterprise network planner is faced with a formidable task to develop a network that optimises function and cost when all the factors affecting function and cost are uncertain and rapidly changing. The trend towards outsourcing of service activities means the network must be designed to minimise the requirement for highly skilled operators. The mission critical network developed for the modern enterprise must therefore solve problems associated with:
Jtec’s SolutionJtec is committed to solving the network problem for the enterprise backbone and wide area network. The company addresses the problem with a combination of technology, product architecture and customer services. Technology comes in the form of ISDN, Frame Relay, IP and ATM. In each area, Jtec has designed products from the technology up using a combination of international and industry standards. Jtec’s ownership of designs and intellectual property across these key technologies allows the company to build a range of products incorporating the best technology for the job. Further, it allows Jtec to design products that support intelligent interworking between the different technologies. Intelligent interworking relieves the network planner of the task of designing the network around the complexities of each technology. Other vendors promote solutions that require the network planner to be expert in the intricacies of complex interfaces and a plethora of protocols. Jtec products interwork with each other and with competitor products across simplified common industry interfaces. Features such as PBX protocol conversion and embedded LAN emulation over ATM allow network planners to specify industry standard G.703 and Ethernet interfaces, rather than multi level protocol stacks. Apart from the saving in network design, specification, installation and operating costs, the major benefit from intelligent interworking is the ability to protect historical investments. Existing network equipment will continue to work, and will be more valuable after Jtec intelligent interworking is added. Jtec product architectures allow a network to be designed in rings, stars and point to point links. Interconnection within and between sites is accomplished with private transmission, lines leased from carriers, or with carrier services. Multi-function products supporting intelligent interworking features are available in chassis sizes from three ports to more than 60 ports per chassis. Chassis may be stacked if required for additional port density. All Jtec products support circuit bearer class of service. That is, the products provide for robust clock synchronisation between the underlying technology and ISDN like circuit services. This means that enterprises can use any combination of Jtec products to provide the equivalent of carrier class services throughout the enterprise network. Circuit bearer class of service is available with Jtec’s rich compression and switching technologies to deliver high quality bandwidth efficiencies across the enterprise. Jtec’s approach to the whole of enterprise mission critical network is to provide crucial building blocks that may be used independently, in conjunction with competitor products, or with other Jtec products to create networks of the varying size and complexity required by enterprises. In this paper, we highlight some key Jtec network building blocks that may be used by network planners to build mission critical networks. The functions highlighted include:
Site to Site Trunks Enterprises occupy sites. In some cases, a site may be a single office, or it could be a number of floors in a building, or several buildings in one complex. Sites may be dedicated to a single function (such as Sales or Administration) or may include many functions. Multi function sites typically include some combination of enterprise administration, product development, production, sales and distribution functions. Interconnecting sites is a key requirement of the whole of enterprise mission critical network. Jtec’s Virtual eXchange and InterXchange products offer a variety of means of interconnecting sites. Enterprises may use Virtual eXchange and InterXchange to form inter-site trunks over private transmission, leased lines or carrier services. The choice of trunk technology is generally driven by the required capacity of the trunk. For trunks that are used occasionally, where the requirement is predominantly voice, or where data requirements can be met by switched circuits, public ISDN service is an appropriate choice. Where a mix of voice and data is required, it may also be appropriate to implement a private ISDN over a dedicated transmission link. ISDN is ideally suited to traffic loads that can be addressed by multiplexing and switching 64 kbps circuits. Diagram 1 Jtec Virtual eXchange switches connected between sites by trunks of up to 2.048 Mbps create a virtual ISDN network (see Diagram 1). Attached equipment that is capable of generating switched call requests will be allocated 64 kbps of trunk bandwidth per call on demand. Sub-multiplexing within 64kbps switched calls may be used to allocate bandwidth to compressed voice or data in 8 kbps increments. Alternatively, capacity within 64kbps increments may be shared via the Jtec TimeFrameTM trunk technology. Some enterprises require inter site trunks at more than 2.048 Mbps. Until recently, such trunks were not available to enterprises. Now a variety of physical methods are available to provide transmission bandwidth at higher rates to enterprises. Such methods are depicted in Diagram 2 and include carrier large megabit leased line services, private microwave, private (so-called “dark”) fibre and public ATM services. Bandwidth available from high capacity transmission systems can be provided at E1 / 2.048 Mbps, E2 / 8.448 Mbps, E3 / 34 Mbps and STM-1 / 155 Mbps. Jtec’s InterXchange product range addresses high capacity trunks using ATM as the trunking protocol. Diagram 2 InterXchange uses ATM as a multiplexing method to provide Dynamic Bandwidth Allocation. Intelligent interworking interfaces on the InterXchange connect existing enterprise equipment directly to the ATM environment using industry standard interfaces. Thus there is no requirement to adopt an all-ATM strategy to use InterXchange. Standard G.703/G.704 interfaces, Ethernet and V Series physical interfaces connect directly to InterXchange. InterXchange ports incorporate the intelligence to adapt switched 64 Kbps circuits, HDLC, IP and Ethernet traffic directly to ATM. Narrowband signalling is interpreted, allowing ATM bandwidth to be allocated on demand for switched 64 kbps circuits. HDLC streams are terminated and idle frames are filtered out prior to transport over the ATM trunk. IP routing over ATM and native LAN emulation allow connectivity across the WAN without the need for complex address server management associated with other implementations. Traffic priority queues are used to allocate trunk bandwidth. InterXchange intelligent interworking filters out idle traffic and dynamically allocates trunk bandwidth according to instantaneous demand. (A Jtec White Paper describing Dynamic Bandwidth Allocation in more detail is available on request.) InterXchange trunk interfaces include the following:
Additional trunk interfaces are under development. Contact your Jtec Representative for details. Central Sites Larger enterprise sites generally contain the production centre of the enterprise. Such centres often involve multiple buildings, or multiple floors within a building. Different enterprises have different requirements, but many central sites will have requirements for client-server communications, voice internetworking, digital circuits, video conferencing, production process control and telemetry. Jtec’s InterXchange product may be configured as a distributed switching broadband backbone with the capability to address all of these needs. InterXchange is able to simultaneously provide WAN access for interconnection to other sites. Jtec Virtual eXchange may be used to provide a narrowband overlay for concentration of lower speed interfaces and to support advanced narrowband features such as voice compression, protocol conversion, and narrowband switching. Diagram 3 InterXchange is built on an architecture that creates an SDH quality transmission infrastructure overlaid with ATM (see Diagram 3). The architecture enables the distribution of a public network quality clock around the enterprise central site allowing PBX interworking and support for telemetry and process control equipment. Importantly, the SDH architecture provides for rapid network healing response in the event of a loss of transmission. Software based healing algorithms used in other architectures heal within tens of seconds. The Jtec architecture supports healing in tens of milliseconds. Metropolitan Area Networks The very existence of cities is a communications metaphor. Cities are areas of intense communication between their citizens. Trade between businesses and their customers within a city often greatly exceeds that between the business and its customers in other cities. Many enterprises have multiple sites within a city. Moreover, enterprises within cities often form communities of interest, evidenced by the tendency for similar types of enterprise to be concentrated in particular cities. It follows that there is demand for high quality communications over metropolitan areas. Either to provide communications between multiple sites of a single enterprise, or to provide communications between enterprises in communities of interest. Direct support of fibre and microwave trunks by InterXchange allows integrated multi-media networks to readily be constructed over metropolitan areas. Links in the InterXchange SDH backbone may be constructed from multi-mode fibre, single mode fibre or G.703 microwave links (see Diagram 4). Each chassis supports two trunks leading to the next adjacent chassis. Any two of single mode, multi-mode and G.703 interfaces may be supported on a single chassis. Self-healing metropolitan network loops may therefore be constructed using a variety of transmission media of a type now available to large enterprises. It is recommended that any one loop be limited to 30 chassis, to ensure clock distribution characteristics remain within ITU recommended limits. A metropolitan area network may be used by the enterprise to create a high speed corporate intranet, a metropolitan PBX network, or to deliver advanced multi-media services to its metropolitan sites. In many cases the requirement is simply to provision many digital cross connects over the city to replace leased digital links. Diagram 4 If required for clocking or capacity reasons, multiple loops may be constructed and interconnected to form the metropolitan area network. Diagram 5 Interconnection between loops may be made using ATM UNI trunks or any appropriate higher layer protocol supported by InterXchange. (Example in Diagram 5 — Jtec Representatives can provide further details) Remote Access An enterprise’s clients will include employees, customers and suppliers who are remote from the key enterprise sites. Employees may wish to access the enterprise network while travelling, or may sometimes work from home. Jtec provides a range of remote access solutions to meet the needs of remote sites. Remote sites may access the network via switched services such as the public switched telephone network, or ISDN. Alternatively, connection may be via fixed links such as n x 64 kbps or 2.048 Mbps lines leased from carriers. Where available permanent virtual circuit services, such as ATM may also be used. Diagram 6 Jtec’s wide range of remote access products (as shown in Diagram 6) provide the enterprise with considerable flexibility in providing access at a scale and cost appropriate to the end user. Remote access raises the issue of security. Jtec remote access solutions support calling line identification, PAP/CHAP and RADIUS security as required by the type of access provided. Encryption and firewalls, if required are provided by third parties. Service Projection The complexity of today’s networks requires enterprise network planners to think like a service provider. Network clients are increasingly regarding the network as fundamental infrastructure in support of the business mission. Clients expect to be able to add an application, or bring a new site into operation without fundamentally redesigning the network. Each new site added, or new application required, by the business must be supported by making incremental changes to the network. In practical terms, this means the network must be constructed from multi-functional network elements that can be readily adapted to support the new site or new application. These multi-functional network elements must support LAN, serial data, telephony, digital circuits and video traffic and present it over digital circuits or public network services. In some cases, the network elements must give the appearance of public carrier services so that end equipment expecting the features of a public carrier service may connect directly to the enterprise network. (For example, a PBX expecting to make switched calls will be attached to an interface that behaves as if it were a public ISDN network.) Jtec networks have the ability to deliver new features by simply adding modules or by reconfiguring software. Jtec uses the term “service projection” to describe the network’s ability to project new network services in increments throughout the network. Examples of services projected by the Jtec whole of enterprise mission critical network include:
These important network services may be projected over digital lines, ISDN or ATM networks using Virtual eXchange or InterXchange. The choice of product used will depend on the particular service required and the scale of the requirement. The table below illustrates the choices available.
Jtec offers Network Design, Installation, and Facilities Management services to support enterprises in creating networks to meet the ever-changing needs of the whole of enterprise mission critical network. Whole of Enterprise Network The modularity of the Jtec network building blocks allows a whole of enterprise network to be constructed as cost and capacity requires. The network provides the appearance and services of a public carrier infrastructure augmented by a rich array of value added services. Proven interworking with public network services and the ability to value add those services allows the whole of enterprise network to be a hybrid of public services, leased digital links and private infrastructure. The enterprise is not forced to make a strategic choice between owning a network or relying on carrier services. The balance between carrier and enterprise services may be adjusted as changing circumstances dictate. Likewise, the choice between in-house management and out-sourcing is easy. Jtec is able to arrange financing of the network and facilities management if required. Should the enterprise choose in-house management, Jtec’s OmniVision network management product provides the ability to manage all Jtec technology through a single management platform. OmniVision is SNMP based allowing ready integration with third party systems. It is built to the ITU TMN (International Telecommunications Union’s Telecommunications Managed Networks) architecture and is thus designed to be integrated into high level enterprise and service management systems. |
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