ATM ACCESS: THE GENESIS OF A NEW NETWORK

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1 DATA COMMUNICATIONS MANAGEMENT ATM ACCESS: THE GENESIS OF A NEW NETWORK William R. Koss INSIDE ATM Today: The Network Core; LEC, CLEC, IAP, ISP, IXC, and CIXC; ATM Tomorrow; The ATM WAN; Enterprise Network Performance; Service Provider Network Performance; Quality of Service; Inclusion, Unification, and Expansion; Scalability; Integrated Services; Outsourcing Services; Key Technologies for the ATM WAN; ATM WAN: Should You Start Now? INTRODUCTION Data communications has come a long way in the past six years. In 1992, many users deploying wide area networks (WANs) still thought in terms of 56K frame relay and fractional T1 speeds as state of the art. Some six years later, the World Wide Web (WWW) has driven most of us to deploy V.90 standard modems in the home or explore the possibilities of cable modems, ISDN, and xdsl technologies. In the enterprise network, network backbones are now primarily cell-based backbones. Long gone are shared backbones such as token-ring, Ethernet, and collapsed router backbones. FDDI is still around, but nobody is getting excited about DAS and SAS. The network core within the enterprise and within the service provider (LEC, CLEC, IAP, ISP, IXC, and CIXC) networks is using a cellbased technology called ATM (asynchronous transfer mode). One may have heard of ATM it was all the rage in Everyone went through a few years of ATM Year One, Year Two, Year Three, and then the marketing hype finally fizzled out. In its place came tag switching, voice over IP, IP over SO- NET, xdsl, and terabit routers. All PAYOFF IDEA Some industry pundits once thought that ATM would take over the network, from the desktop to the wide area network. ATM is now widely deployed in campus networks, and some people believe it will never go beyond the campus and into the wide area network (WAN). This notion is wrong. ATM is being implemented in both public and private WANs. This article describes the business drivers within service provider and enterprise networks. It looks at requirements for enterprise customers deploying ATM access into an ATM WAN. It also provides some guidelines to help determine if one should start looking at ATM for the WAN. 04/99 Auerbach Publications 1999 CRC Press LLC

2 this occurred while the service providers were deploying ATM within their network cores and most enterprise IT managers were completing the deployment of ATM backbones to service the growing demand for bandwidth and network performance. The purpose of this article is to explore the emergence of ATM into the wide area network and the outline the challenges and techniques that will used to deliver increased bandwidth for voice, data, and video services. ATM TODAY: THE NETWORK CORE For discussion purposes, existing ATM networks can be divided into two primary categories: (1) carrier class networks maintained by service providers, and (2) enterprise networks maintained by corporations and organizations and primarily intended for private use. To understand the deployment of ATM into the WAN, one can start by examining how ATM is deployed within each of the defined categories. Not too long ago many people referred to the phone companies as the Telco or carrier markets. Today, this is an injustice. Such a large number of companies exist that offer some type of network access that the market they are part of is now refered to as service providers. Within the service provider market, many types of companies and market verticals can be defined. This article concentrates on the following acronyms that define the major vertical elements of the service provider market: LEC: Local exchange carrier that provides local access to telecommunication services; formally defined as regional Bell operating companies (RBOCs). CLEC: Competitive local exchange carrier. Companies that provide local access to telecommunication services. Most CLECs have emerged in past few years to compete for local telephone service against LECs. IAP: Internet access provider. Companies that provide wholesale Internet backbone transport and access. Examples are UUNET, ANS, SAVVIS, and Concentric. ISP: Internet service provider. Companies that provide local Internet access and Internet-based services. IXC: Interchange carrier. Companies that provide inter-lata services between LATAs within an interstate or intrastate basis. AT&T, MCI Worldcomm, and Sprint are the primary IXCs within the United States. CIXC: For lack of a better term, competitive interchange carrier. This vertical represents companies that are developing inter-lata services based on their own developing network infrastructure. The prominent players are Level3, Qwest, and IXC Communications.

3 Each service provider has developed a different type of network to meet its business and customer requirements. For discussion purposes, some generalities that encompass many of the service provider networks can be defined. By the end of 1998, most service providers within the United States had deployed ATM within their networks. Those that have are typically well-established companies or aggressive young companies with a business strategy that depends on leveraging the technical advantages of ATM to compete for customers. For the purposes of this article, international service providers or small market players that have yet to establish themselves are not discussed here. The reason for this is that each international market is different, and the smaller market players have yet to develop enough mass to affect the market dynamics. The existing IXCs and LECs are confronted with a series of challenges that can best described as legacy challenges. Most IXCs and LECs have created several networks to deliver customer services. They have networks for voice services, packet-based IP, frame relay, local access, and ATM. The emerging CLECs and CIXCs have bypassed legacy technologies and deployed ATM as their transport technology. The competitive nature of the service provider market requires that service providers be able to address the following challenges. provide the client an end-to-end network solution provide application services such as Internet access, global intranets, Web-based co-location, Web-based transaction and application support, and data warehousing unify their networks and provide a single managed service reduce duplicated costs and overall operational costs deliver integrated voice, data, and video services to the client provide unified billing and service-level agreements (SLAs) that guarantee quality of service The IXCs and LECs that are the incumbent service providers are challenged to (1) reduce cost, (2) improve performance, (3) unify services, and (4) deliver higher quality services. Their plan is to achieve these objectives by leveraging the strengths of technologies such as ATM. The reason ATM is important is that it currently exists within many of the service provider core networks and ATM has several important elements that are driving ATM deployment, including: It solves the TDM problem; existing networks based on time-division multiplexing cannot support future network growth. It provides support for all services; ATM supports three primary services that service providers are concerned with: voice, data, and video.

4 It exists and is proven; ATM is already deployed in the network core. It is proven, understood, and technical resources have been trained to support the technology. It reduces deployment and operational costs; ATM access equipment is less expensive and less complicated. The long-term support and operational costs of ATM networks is projected to provide significant long-term savings. As the IXCs and LECs view ATM as the unifying network technology that is able to provide a solution from the carrier core to customer premises, the CLECs and CIXCs view ATM as the network infrastructure of choice. Nearly all CLECs and CIXCs have developed extensive network infrastructures that built upon ATM. ATM provides the universal network foundation to support all services and provide scalable bandwidth. As much as the IXCs and LECs view ATM as the future, CLECs and CIXCs view ATM as the technology that enables them to compete without the encumbrance of legacy networks. Within the enterprise market, ATM has been widely deployed as the universal backbone of the network. Some users have invested in desktop ATM solutions, but many users have built successful network backbones using ATM solutions that encompass Ethernet or token-ring switching as the final connection to the desktop. Most enterprise ATM backbones are deployed within buildings and campus networks. Using a switched cell network architecture, ATM backbones running at speeds of OC3 are capable of supporting an immense amount of traffic and adequately dealing with the challenge of performance-intensive applications. Similar to the service provider market, several important elements are driving the deployment of ATM into the WAN within the enterprise market: 1. It solves the performance problem. ATM delivers the bandwidth demanded by customers in scalable increments and meters from the customer premise to the network core. 2. It provides support for all services. ATM provides the foundation for voice, data, and video support within a defined standard. 3. It exists and is proven. ATM is already deployed in the network core. It is proven, understood, and technical resources have been trained to support the technology ATM TOMORROW: THE ATM WAN The deployment of ATM into the WAN has been a slow process. At present, the majority of ATM WAN installations have been for DS1 speeds. Several reasons can be attributed the slow deployment of ATM technology:

5 ATM has primarily been used as a backbone technology for highspeed network trunks emergence of possible alternative technologies such as Everything over IP SONET service providers have been slow to develop infrastructure to support ATM-based services continued strong demand of frame relay-based services market readiness and demand has been lacking as many enterprise users complete network deployments based on core technologies such as IP, 100BT, and gigabit Ethernet and frame relay Y2K readiness and WWW integration have consumed IT resources, inhibiting planned network upgrades Despite these challenges, 1998 was an important milestone in the ATM WAN market. Major service providers began announcing the availability of high-speed ATM services. Sprint announced its ATM intentions in June 1998, and UUNET announced its intention to deliver high-speed ATMbased services in To understand why ATM will grow in the WAN, one must first define the business challenges that will compel both the enterprise users and service providers to deploy ATM in the WAN. Enterprise Network Performance This is an important concern for enterprise IT managers. Applications are driving the expansion of networks and the need to deliver high-speed services to an increasing number of users. Enterprise managers are continually faced with the challenge of supporting an increased number of applications that require an increased amount of network resources. Collaborative group documents, business presentations, and reports are routinely sent via or the Internet as the work environment becomes increasingly mobile. The demand for increased access to information at the desktop has created a demand for better network performance. Applications that have been driven out from the network core to the remote offices require more bandwidth for better performance. The ATM core of the enterprise network is and will be pushed out to the edges of the network. Service Provider Network Performance Service providers are challenged with the need to deliver more services other than bandwidth and network access. They are challenged to provide services such as data warehousing, data archiving, co-location of Web services, business-class Internet access (>T1), corporate intranets or VPN services, and workgroup services. To satisfy the demands of their clients, the service providers are challenged to move ATM for their network core to the customer premise. Even today, several service providers

6 have tariffed their ATM services at the same rate that they provide frame relay service. Quality of Service An important technical feature of ATM is that it provides multiple levels of quality of service, and it has internal provision to address the needs of flow control and dynamic bandwidth allocation. Clients are demanding a guaranteed level of service for network dollar, and ATM enables the service provider a mechanism to provide service-level agreements (SLAs). The classic example is of two customers, one who has contracted for 6Mbps service and one who has contracted for 10Mbps service. The flow control capabilities of ATM allow the service providers to guarantee the expected level of service for each customer, although the customers may be sharing the same network link. Clients receive a different billing rate for their service, and the service provider can maximize their network bandwidth. Inclusion, Unification, and Expansion The conversion of the network core to ATM within the enterprise and service provider networks provides a strong impetus to expand these networks to include other users or networks. Unifying and standardizing network technology are methods of reducing cost and improving reliability and serviceability. In order to simplify the network, ATM will move from the network core to the edge of the network. Scalability ATM is dynamically scalable and it provides metered bandwidth that conforms to the infrastructure of networks maintained by service providers as well as enterprise users. ATM enables the service providers to deliver bandwidth that meets the demands of users. Other competing technologies such as xdsl require bandwidth services that are asymmetrical to the network. Users will demand bandwidth in increments of 1.5Mbps, 3Mbps, 6Mbps, 12Mbps, DS3, OC-3c, and OC12. Integrated Services ATM provides the only standardized method for unifying network services under a single network medium. ATM supports both data and voice, as well as video services. The unification of voice, data, and video is an important long-term objective for both enterprise users and service provides. Enterprise users long for the day when they can contract for one service and one bill that includes voice, data, and video services. By deploying ATM to the customer premise, Service Providers can begin to unify network functions and deliver the long-sought-after single pipe that provides all functions.

7 Outsourcing Services ATM enables service providers to deliver high-speed, transparent LAN services (TLS). TLS services provide a simple means of providing LAN-to- LAN extension without the need to deploy a complex solution. This enables service providers to provide outsourcing services to clients seeking to bundle network WAN services to achieve an overall lower operational network cost. When examining how ATM will be deployed in the future in the enterprise market, one is primarily concerned with the WAN. Although the rapid emergence of switched technologies such as 100BT Ethernet and gigabit Ethernet at low cost points successfully stunted the deployment of ATM to the desktop ATM found a home in the network core it was in the core of the network that ATM provided the speeds necessary to reduce network congestion. It is only now that the extensive investments made in ATM backbone technology can be leveraged to deliver in-demand services across the network topology. Exhibit 1 illustrates the deployment of ATM access services within the enterprise market. From the service provider perspective, the ATM network of tomorrow involves migration of the ATM network from the core of the network to the customer premises. By expanding the ATM as the network transport, service providers are presented with a viable strategy to modernize the components of their networks that generate profits but at a considerable cost. The large incumbent interchange carriers such as Sprint, Williams, MCI Worldcomm and AT&T have multiple networks under management. These networks include Frame Relay, voice, IP, and ATM. Expanding ATM throughout their networks allows the incumbents to (1) reduce costs, (2) deliver high-speed services, (3) unify networks, and (4) provide new CPE-based services. Without exception, the new CLECs and CIXCs have built new networks almost entirely based on ATM as the core transport. Each of these new companies has seized on ATM as their preferred transport technology. Thus, none of these companies is encumbered with legacy networks such as Frame Relay or circuit-switched technologies. In short, when one thinks about ATM access, one is thinking about a CPE device that is designed to be an access mechanism that transports CPE services into the ATM network for delivery across the service provider network. Exhibit 2 illustrates ATM access into the ATM service provider backbone network from two customer sites. KEY TECHNOLOGIES FOR THE ATM WAN The ATM WAN of tomorrow will be a combination of core ATM technologies and transition technologies required for supporting legacy networks. When examining the deployment strategy of ATM access equipment within the ATM WAN of tomorrow, one does so from two per-

8 EXHIBIT 1 ATM Deployment in Enterprise Networks

9 EXHIBIT 2 ATM Access from Customer Site to Service Provider spectives. The first perspective is the user or CPE side and the second perspective is the network or service provider side. Using the CPE/service provider model, one can begin to define the system required for ATM access. On the service provider side, ATM services will be delivered at various speeds using a variety of interfaces. Typically, ATM access devices will support the following on the service provider side: DS1/E1 interface DS3/E3 interface OC-3c interface inverse muxing over ATM (IMA) interface add drop mux and add drop bypass

10 The service provider side of ATM access devices are simple compared to the variety of services that must be supported on the CPE side. The CPE side of ATM access devices must achieve two objectives: they must support the services that customers will use going forward, and they must also support a variety of legacy network technologies and services that clients have deployed over the years. It must be remembered that a motivating component of ATM is the ability to provide a consolidation of technologies and services. The following outlines the primary CPE side requirements: LAN interface: 10/100 Ethernet, 4/16 Token Ring, and FDDI IP routing support: static routing and default gateway forwarding support transparent LAN service support: bridging LAN client support: LAN client provides support for SVCs and bandwidth management and interoperability in enterprise networks with native ATM devices Combining the service provider and CPE side features, one creates what can be called an integrated access device (IAD) or multi-service access concentrator (MAC). The objective of this device is to provide userto-network connectivity. It is not a router and it is not a switch it is an access device. In simple terms, it can be considered a fast segmentation and reassembly (SARing) engine that transports voice and data into an ATM stream. The primary objective of MACs will be to balance their cost and simplicity in order to leverage the benefits of ATM. Unified services or single-pipe strategy is a driving force behind the deployment of ATM; but if the devices used to provide ATM access are expensive or complicated, the compelling reasons to deploy ATM are diminished. Enterprise IT managers and service providers have a common objective that ATM and MACs must achieve long-term operational cost reduction. As enterprise networks and service providers begin the migration out from the network core, support for legacy technologies will be important in-demand features. Not only will the IXCs have legacy networks, but many enterprise users will have a mix of legacy technologies as well. The objective will be to provide an orderly transition to ATM, starting with the locations with critical needs. In order to achieve this process, MACs will need to provide support for legacy services such as Frame Relay. An essential element of this requirement will be for MACs to support Frame Relay connections from routers and FRADs, as well as FRF 5 and FRF 8 for support of Frame-to-ATM and Frame-to-ATM-to-Frame services. As much as MACs must be data orientated to support the variety of services typically found at the remote site location, they must also be able to support a variety of voice services. A primary benefit of ATM is the integration of voice and data on a single pipe. The benefits of the

11 technology are greatly reduced if all one can get is a faster pipe and still require a different connection for voice services. Thus, MACs need to possess strong voice services. These services include: circuit emulation services: structured and unstructured transmission of DS1/E1 streams for support of digital PBX interconnect FXO/FXS POTs: support for analog PBXs as well as dial tone, PLAR, and ring generator voice and silence suppression and compression AAL2 voice services that support dynamic bandwidth allocation through SVCs As well as supporting a variety of services, MACs must also support a variety of network management services. MACs will be deployed by both enterprise users and service provider users. Thus, it is important for MACs to support features that enable each to manage and support the devices. The primary objective is for MACs to be lights-out devices that are installed, configured, and forgotten. Unfortunately, network devices rarely live up to such lofty goals and at times will be in need of management services. In this case, it will important for MACs to support a variety of punch list network management features. These features include: Web-based management Telnet SNMP support for popular network management platforms with MIB extensions CRAFT interface out-of-band management via modem An important tactical capability in the deployment of MACs will be support for inverse muxing over ATM (IMA). IMA leverages two market conditions for the service provider and enterprise client. At present, many service providers are forced to deploy full DS3 circuits for clients that desire to scale above the T1 range. Unfortunately, many clients do not require a full DS3. In other cases, clients are demanding >T1 service in areas where DS3 is not readily available. The solution to this challenge can be found in IMA. IMA allows T1 lines to be bonded together to deliver access services that are >T1, but less than DS3. This elegant strategy provides a gradual scale in services and cost as network demands warrant. Exhibit 3 illustrates the deployment of IMA services. ATM WAN: SHOULD YOU START NOW? Why ATM will be important in the WAN is known; now one needs to ensure that one will be prepared to undertake the transition. From a prep-

12 EXHIBIT 3 Deployment of Inverse Multiplexing over ATM (IMA) Services

13 aration perspective, the following questions provide a starting point to determine whether or not one should initiate programs to begin transitioning the WAN transport to ATM-based services. Do you have remote locations that require improved performance or locations in your network that would benefit by extending your ATM backbone to include their location? Are you looking to reduce long-term costs and unify voice and data services? Do you have E-commerce, or Web-based applications that require dedicated Internet access above T1 speeds? Can you benefit from leveraging the infrastructure of service providers to provide data warehousing, co-location of Web servers, and high-speed intranet services? Do you have major application initiatives underway that will increase the demands for network bandwidth throughout your network over the next 12 to 24 months? Are you looking to contract for guaranteed network bandwidth for some or all of your network locations? Is network performance a mission-critical requirement for your business? Do you have or will you have mission-critical applications that are dependent on network performance? Are you interested in positioning your network infrastructure to support video-based applications such as conferencing and training? Are long-term cost reduction, network simplification, and performance long-term objectives for your IS organization? CONCLUSION The genesis of the new network has begun. The start has been slow but the conclusion is inevitable. ATM is and will be deployed as the transport of choice for wide area networking. Service providers of all types are deploying ATM for solid business reasons. ATM provides key advantages not found in other WAN technologies: namely, quality of service, unification of services (voice, data, video), and superior scalability. Enterprise networks are being deployed with public or private ATM backbones. This will be extended to remote offices and locations, where ATM access solutions will be deployed for the following reasons: Cost/performance balance: increase network performance in a manner that allows for scalable migration of services based on a cost/need ratio. Simplified billing and service level agreements: lower service cost, simplified billing statements, and guaranteed service that enable the enterprise users to purchase only what they require.

14 Leverage investments in public and private backbones: effective use of ATM core infrastructures that are already deployed will lead to improved services and lower, long-term costs. Reduce acquisition and operational costs: deploy less-expensive technological solutions that provide long-term, low cost, lights out operational costs. ATM is the only technology that is standards based and can be used to deliver multi-service networking throughout the wide area network. In addition, ATM is the only technology that can be used by enterprise users and service providers to reduce their equipment acquisition costs and ongoing operational costs over the long term. William R. Koss has held numerous technical, sales, international sales, and marketing positions with various industry participants such as CrossComm Corporation, Stratus Computer, SDL Communications, and Sonoma Systems. He is currently involved in the development of business strategies for the emerging ATM market within the service provider industry.