INTERNET ACCESS VIA CABLE TV: HIGH SPEED ACCESS TO THE INFORMATION HIGHWAY Lynn Jones Digital Equipment Corporation

Abstract countries around the world. In early 1994, it was estimated that on the average, a new Internet access has become a feeding frenzy. computer was added to the Internet every 30 Dial-up access to the World Wide Web just seconds.ii The growth of the Internet contin­ isn't fast enough. Your subscribers know ues to be exponential. that cable TV can give them access to hyper­ text at the speed of a bullet train, and they The cable TV industry has the capability want it. Now what do you do? to provide subscribers with Internet access at speeds unmatched in price/performance by How do you separate the hype from the hy­ any other medium. Using the ubiquitous, ex­ pertext? For that matter, what is hypertext? isting Hybrid Fiber Coax (HFC) infrastructure This paper will answer these questions and in place in the US, Canada, and many coun­ more, providing a framework within which tries around the world today, the cable indus­ to plan and implement Internet access on try can give customers high speed access at a your system. It will give you a crash course much lower cost - a key criteria for Internet on the Internet and show how the informa­ users. tion highway is being created today with the Internet and cable TV. Rapid access to and provision of pic­ tures, sound, video, audio, and integrated text and graphics are all made possible by access­ INTRODUCTION ing Internet sites on the World Wide Web, using a Web browser program from a personal "Internet over cable TV will receive more computer connected to the Internet via cable general press (Information Superhighway) television. By using standard channels, one attention than any other carrier-based activity forward and one reverse, on an existing enter­ in 1995 and become the most important tool tainment cable system, cable operators can for work-at-home since the advent of the PC, offer businesses, telecommuters, doctors, modem and facsimile terminal" teachers, students, and consumers access the state-of-the-art capabilities available on in­ Dr. Jerome Lucas formation highway today. TeleStrategies Insight Newsletter January 1995 This paper discusses creating such net­ works using an Ethernet to cable TV bridge, The commercialization of the Internet has brouter, or personal modem at each business, opened the door for access to the largest in­ hospital, school, or home, coupled with a formation network in the world. The Internet translator in the Cable TV headend and a connects an estimated 39K networks, 4.9M backbone router to the Internet at one location hostsi, and over 30M users in more than 127 on the network. Each user on the network has

1995 NCTA Technical Papers -398- access to the Internet, as well a shared 10 In the mid-1970's, the Defense Advanced Mbps access to each other. The value of the Research Project Agency (DARPA) funded cable connection to the customer is increased research to develop a set of networking stan­ by orders of magnitude. dards or protocols, that specify how comput­ ers would communicate over an internet, as The key is the ability of cable to provide well as a series of conventions for intercon­ a fully distributed network, rather than cus­ necting networks and routing traffic. The re­ tomers using expensive point-to-point leased sult was TCPIIP (Transmission Control Pro­ lines for direct connection to the Internet, or tocol/Internet Protocol). During the late slow dial-up lines for indirect connection 1970's, DARPA also funded research into through online services. packet switched networking and implemented a network called the ARP Anet. The goals of this paper are to explain the network technology, components, and archi­ TCPIIP became the only effective way to tecture, and the methodology which will pro­ communicate between computers from differ­ vide the cable operator with a foundation on ent manufacturers. It appealed to schools, in­ which to plan and build such a network. Case stitutions, and businesses, who did not want to studies of actual networks are used to illus­ be tied to one vendor's equipment, and who trate possible configurations. wanted to protect their investment in existing equipment. The convergence of the cable and data communications industries provides enor­ In the early 1980's Ethernet local area mous opportunities, but carries with it the networks (LANs) proliferated. Ethernet, de­ challenges of learning about each others' veloped by Metcalfe and Boggs in 1976, used technologies. This paper is intended to serve a coaxial cable network, in which all stations as a starting point, assuming little or no monitor the cable (the ether) during their own knowledge of data communications or the In­ transmission, terminating transmission im­ ternet. mediately if a collision is detected. This cre­ ated a new demand: rather than connecting to A BRIEF HISTORY OF THE INTERNET a single large timesharing computer per site, organizations wanted to connect the ARP Anet The evolution of cable TV data networks to their entire local network. This would al­ can be seen to parallel the development and low all the computers on that LAN to access growth of the Internet. Both have the roots of ARPANET facilities. their technology growing largely out of mili­ tary applications with initial use and promo­ In 1986, the National Science Foundation tion of the technology by the education and founded NSFNET to connect its networks research community, followed by adoption in centered around its 6 supercomputers into a the commercial marketplace, and finally network backbone that ties into the ARPA­ reaching widespread use in the home. NET.

A brief history of the Internet helps to This network arrangement was enor­ understand why it is organized the way it is, mously successful, and the Internet was born. and how cable networks connect to it. With success came the need to upgrade com­ pute resources and leased line speeds, which continues today.

1995 NCTA Technical Papers -399- are not only possible, but possible on an in­ ternational level. Internet marketing and ad­ vertising will change the way products are MANAGEMENT OF THE INTERNET promoted.

The Internet has evolved from a loose The commercialization of the Internet federation of networks, to a network with a will forever change the future of both small character all its own. There is no central business and worldwide commerce. It will management, but rather a group of organiza­ also forever change what the Internet is. tions who steer its activities. These groups include the Internet Architecture Board (lAB), WHO ARE THE USERS? the Internet Society (ISOC), and the Internet Engineering Task Force (IETF). Users of the Internet include companies, universities, colleges, K-12 schools, research Another unique aspect of the Internet is groups, and individual users. that, as it is not owned by any one party, it is also not paid for or funded by any one organi­ The majority of universities and research zation. NSF, which subsidized its develop­ facilities have Internet access. Many compa­ ment is phasing out its $11.5M subsidy. Pri­ nies also have access. There is now a major vatization of the Internet remains a hot topic. initiative to connect K-12 schools. Individual Many third party Internet access providers users are largely an untapped market, as until have sprung up to offer Internet access to recently, acquiring Internet access required businesses and individuals. specialized knowledge of UNIX and TCP/IP.

THE COMMERCIALIZATION OF THE The popular press is rife with articles on INTERNET the wealth of information available on the In­ ternet, as well as on the need for a national, as Those who stand to gain most from the well as global, Information Highway. This commercialization of the Internet are small has sparked a feeding frenzy of interest in businesses, K-12 schools, home workers, and connecting up to the Internet. To people to­ recreational users. Corporations, research day, the Internet is the Information Highway. institutions, and universities have been using the Internet for many years. Big business has WHAT ARE THE APPLICATIONS? also been using private wide area networks (WANs) for years as well. (W ANs being es­ Applications on the Internet started out sentially company-owned internets.) with simple text-based applications, such as electronic mail. Today' s applications are Prior to the commercialization of the In­ highly visual - containing color pictures, ternet, small businesses, schools, and indi­ sound, graphics, video, and other data­ viduals could not afford the high price of pri­ intensive information formats. It is the in­ vate W ANs, and were not allowed access to crease in such applications that drives the the Internet. Commercialization opens the need for the "big pipes" that cable TV can door for access to resources previously only provide. available to large organizations. It also opens up a whole new range of possibilities. Virtual corporations and electronic shopping malls

1995 NCTA Technical Papers -400- Electronic Mail Multimedia, client-server based applica­ tions like the Web are the future of the Inter­ The most commonly used application on net, and fuel the need for cable TV speeds. It the Internet is electronic mail, or e-mail. is becoming commonplace for small business, Each user has a unique address and can be schools, and municipalities to have their own reached by anyone else with email access to Web servers. This trend necessitates high­ the Internet. speed symmetrical access, meaning that ac­ cess speed is the same in either direction, Electronic mail is a low-bandwidth, text­ which cable TV is in a unique position to based application. It is a store and forward provide. service, meaning it does not require commu­ nicating users to have an end to end commu­ Wide Area Information Servers (W AIS) nications path set up at the time the message is sent. The message is forwarded and stored W AIS provides a means to search in­ on subsequent computers until is reaches the dexed material using a string of text supplied recipient. by the requester. It allows the user to easily look for information regardless of where it is Traditional low-bandwidth, store and for­ located on the Internet. W AIS is one of many ward applications such as e-mail, do not nec­ such search tools, which instead of browsing essarily require the high-bandwidth capabili­ randomly, allow a user to locate specific in­ ties of a cable TV network. formation.

The World Wide Web Gopher

The World Wide Web, or Web is the Gopher allows a user to tunnel through newest and most often talked about applica­ the Internet and access information without tion on the Internet today. having to know its address. Using gopher is like having a library card catalog to access in­ The World Wide Web provides easily ac­ formation, rather than having to search for it cessible, organized access to the huge amount randomly. of data available on the Internet. The Web uses hypertext, in which displayed informa­ tion contains highlighted words which can be "expanded" with the click of a mouse, provid­ News allows users to access information ing links to other information or files. These on a variety of topics or special interests, and links can be to text, pictures, video clips, is analogous to a discussion group or bulletin audio clips, graphics, etc. board.

The Web is a client-server based applica­ File Transfer Protocol (FTP) tion. Information databases are stored on computers called Web servers. In order to The File Transfer Protocol (ftp) is a cli­ access the Web, a user's computer needs a ent-server based application used for copying piece of software installed called a client, or files from one computer to another over the in hypertext terminology, a browser. Internet. Ftp sets up a real-time connection between the two computers while the copying is taking place.

1995 NCTA Technical Papers -401- either producers or consumers of information, Telnet or prosumers. This societal model, coupled with the need to access the data-intensive Telnet is another client-server application applications used in these activities requires that allows a user to log in to another com­ high-speed symmetrical network access. puter on the Internet. It can allow users to access databases, public information, and li­ Key to the commercial growth is the brary card catalogs. ability to provide users in remote locations, at small companies, and at home with the same Summary high speed access to .information both on community networks and on the Internet that One of the primary lamentations of Internet they are used to having in the workplace. users is the inability to get high speed access to applications such as the World Wide Web As Vint Cerf, one of the founding fathers from their desktop (particularly from home) of the Internet, points out, "The information where a dial-up line may be the only available superhighway model, with low-speed access option. A dial-up line may be fine for e-mail, to a high-speed backbone, is flawed. My ex­ but it is totally unsuitable for applications perience with data networking is that some­ such as the Web. The time it takes to down­ times it makes sense to back out of the drive­ load an image is just too long for the average way at 900 miles per hour. We need to sup­ user to endure. Symmetrical access is also port both low-speed and high-speed access. key, as small companies, schools, and home­ For that reason, narrowband, 128-kb/s inte­ based businesses set up their own Web serv­ grated services digital network connections ers. are not bad, but developments like cable TV­ provided 10-Mbps Ethernet links are even more interesting."iii THE CASE FOR INTERNET ACCESS VIA CABLE TV Standard telephony lines simply do not have the capacity to bring the same bandwidth " ... sometimes it makes sense to back out of to the home as cable TV. the driveway at 900 miles per hour."

Vint Cerf HOW DOES INTERNET ACCESS VIA co-author ofTCP/IPnntemet designer CABLE TV WORK?

Communications mirrors society, as well Data networks use devices such as re­ as changes the way society interacts. Both peaters, bridges, and routers to extend, as well data networks and cable television evolved to as segment, local area networks. bring information to people in physically dis­ tant locations. People and networks have be­ A repeater, as in a cable TV network, come more decentralized. An outgrowth of connects two segments of network cable. It the ability to communicate over wide dis­ retimes, regenerates, and forwards a digital tances has fueled the growth of virtual com­ signal. Repeaters, however, can only extend a panies, telecommuting, distance learning, and high-speed LAN a few thousand yards. other phenomena. Key to these models are the fact that the people using networks can be

1995 NCTA Technical Papers -402- Bridges are used to connect two net­ The cable data modem is specifically de­ works which use the same network signaling signed for cable TV networks. It uses a bi­ and the same media access-control protocol, directional single or dual cable plant to pro­ such as Ethernet. vide symmetrical data transmission at a sig­ naling rate of I 0 Mbps. It uses Quadrature Routers are used to connect two different Phase Shift Keying (QPSK) and has a spectral types of networks, in this case to route IP da­ efficiency of 1.67 bits/Hz. The data modem is tagrams. frequency agile, allowing it to operate in any available standard 6 MHz channel, over a transmit frequency range of 10 MHz to 174 Internet Backbone MHz and a receive frequency of 54 MHz to 550 MHz, with a bit error rate (BER) of 25 dB 9 Routers are also used to connect LANs to C/N: <1 in 10 . W ANs, and make up the Internet backbone. A backbone is a central network to which other Hosts, Nodes, Gateways, and Routers networks are connected. Internet backbone routers were originally It is important to remember that in the called gateways. Gateways were developed to same way that a Local Area Network is a net­ deal with the fact that for internetworking to work of computers, the Internet is essentially work, computers communicating across mul­ a network of networks, consisting of thou­ tiple types of networks needed a way to talk sands of computer networks interconnected by with each other as well as to talk to the inter­ routers. It is also important to make a distinc­ mediary networks in between in order to pass tion between an Internet backbone router and packets. What was needed was an end-to-end a router on the community Ethernet network, protocol. or on the customer LAN, as illustrated in later scenarios. An assumption was made in protocol de­ sign that the networks themselves could not be modified in order to internetwork them. Sample Cable TV Networking Protocol Therefore the gateways had to handle such things as differing maximum packet lengths An example of a protocol in use today for and error characteristics among networks. extending a LAN by cable TV is UniLJNJ(fM, The gateway would know about the end-to­ developed by LANcity Corporation, which: end protocol used by hosts (end user comput­ ers) communicating across multiple networks. • provides two-way, symmetrical data transmission at a signaling rate of 10 Other terms that may be encountered in­ Mbps clude nodes, or packet switch nodes (PSNs), • extends Ethernet beyond its distance which were also originally called interface limitation of 2.2 miles out to 160 miles message processors (IMPs). These terms all • coexists with entertainment and other refer to packet switches in the Internet back­ services on a commercial cable TV net­ bone. An important distinction is that the work term node when talking about the Internet • provides the same data rates and services means something entirely different than it that an Ethernet provides. does when talking about an Ethernet. A node in Internet terminology means a router; a node

1995 NCTA Technical Papers -403- in Ethernet terminology is the end user com­ control and error handling. All of this takes puter, or the Internet's equivalent of a host. place transparently to the user, but internally a complex system of data transmission, traffic Cable Internet Broutersiv control, and error handling ensures that data reaches its destination intact, and in a timely A cable Internet brouter is a combination manner. bridge/router designed to work over commer­ cial cable TV channels, and has a form-factor The brouter receives and forwards Inter­ similar to a standard set-top box. net datagrams, providing buffer management, congestion control, and fairness. This activity Using a cable Internet brouter, all packets allows data waiting to be sent to be stored in that are destined for users on the Metropolitan holding areas, or buffers, and ensures that Area Network (MAN), or the community each user "gets a tum" to transmit or receive network, are transparently bridged using the data when the network is being heavily used, IEEE 802.1D Spanning Tree protocol. In or is "congested", the equivalent of a system other words, packets destined for the com­ of onramps and traffic lights to control traffic munity network are handled by the bridge during rush hour. portion of the Brouter. The brouter also chooses a next hop des­ Routing tables, which determine where to tination for each IP datagram. This means send packets that are destined outside the that the network chooses which computer to community network, or somewhere out on the send the data to next. Each computer in the Internet, are maintained using a routing proto­ chain from sender to receiver is called a hop. col called RIPl. RIP1 is an interior gateway Internally, the network keeps track of the best protocol used to execute distributed routing routes for data at any given time, dependent and reachability algorithms with other routers. on various conditions in the network. For ex­ ample, it may have detected that a certain For packets going out to destinations computer is not operational. Even though across the Internet, or IP packets, the cable taking this route may be the fewest "hops", Internet brouter conforms to specific Internet and hence the natural first choice to send the protocols including the Internet protocol (IP), data to, it will choose an alternative route. Internet Control Message Protocol (ICMP) and others when required. This ensures that For non-IP packets, the Internet brouter other computers in the network receiving the uses the Spanning Tree algorithm and auto­ data packets will be able to process and route matically learns the locations of devices by them to their destination, i.e. that they "speak listening to network traffic, forwarding pack­ the same language". ets only when necessary. Packets that are not forwarded are filtered. The brouter interfaces between an Ether­ net LAN and the cable TV network and per­ Realizing that a standard communication forms required functions such as encapsula­ protocol is needed for cable TV based broad­ tion and decapsulation of the data (i.e. putting band communications networking, the IEEE the data in an envelope with an address on it, 802.14 working group was formed.v and taking it out of the envelope), sending and receiving datagrams, performing IP destina­ The 802.14 protocol will define multiple tion address translation, and network flow physical layer protocols, a MAC layer proto-

1995 NCT A Technical Papers -404- col, cable topologies supported, and other ferent types of network devices) and includes criteria. proprietary extensions to the Mffi for man­ agement of cable TV objects. Also included CABLE DATA NETWORK are the UDP and IP protocols required to ex­ MANAGEMENT change SNMP packets with a network man­ agement station. vi Largely due to the decentralized nature of the Internet, there is no central network man­ It should be noted that these network agement. Each IP network is responsible for management capabilities offer cable operators managing itself. Out of necessity, evolved a an added benefit by proyiding additional in­ common technology used to manage the in­ formation for troubleshooting the physical dividual components of the Internet, which, cable plant and thus improving reliability of like many other protocols originated for the the entertainment network as well. Internet became adopted as the standard for non-Internet networks as well. CABLE DATA NETWORK SECURITY

This management framework is called Once one computer is connected to an­ Simple Network Management Protocol other, some security risk exists, no matter how (SNMP). SNMP evolved from the Simple slight. It is often said that the most secure Gateway Monitoring Protocol (SGMP) which network is no network at all. The more con­ was designed for monitoring IP gateways in nections there are, the greater the risk, and the wide area networks. greater the potential that the network can be broken into by a hacker. SNMP is the defacto standard for net­ work management today. By using SNMP Security can have many different definitions, network management, cable Internet brouters but basically includes the areas of data integ­ and bridges are fully integrated with the net­ rity, user authentication, and privacy. work management of all of the other IP net­ works on the Internet. According to Al Hoover, vice president of information and application services at ANS, SNMP allows the collection of network there are three questions you want to askvii: statistics from widely diverse network com­ ponents by defining the minimum amount of • What are you protecting? information that each IP device should pro­ • Why are you protecting it? vide, via a structure called the MIB • What are you protecting it from? (Management Information Base). An SNMP agent is the software which interfaces be­ The most common security risk in a tween the Mffi and the network management computer network is also the easiest to over­ station (NMS) and processes all of the Mffi look: password security. and management requests and responses to a device. It uses the SNMP protocol to package The first level of security planning is also the request and responses. the toughest: ensuring that users do not pick passwords that are easy to guess, such as the In a cable bridge or Internet brouter, the names of family members. Password genera­ implementation of an SNMP agent supports tion programs are sometimes used to inhibit Mffi IT objects (an extended Mffi to cover dif- this. Hackers will sometimes use stolen pass-

1995 NCTA Technical Papers -405- word lists in what is referred to as a "dictionary attack". Another possibility is Fire walls that the hacker has a password capture pro­ gram, whereby when a legitimate user logs in, One security device often used in corpo­ his or her password is "captured" and reused rate networks is a firewall. A firewall creates by the hacker. Training users on password a safety mechanism whereby all traffic on the security is a key factor in creating a secure network must pass through the firewall com­ network. puter, and only authorized traffic is permitted to pass. A firewall can be between two pri­ For a community-wide Ethernet network vate networks, or betw~en a private and a connected to the Internet, security is ad­ public network, such as the Internet. dressed on several different levels. Application-Layer Gateway Closed User Groups Another security option is an application­ From the community side of the network, layer gateway. With an application-layer security can be provided via a system of gateway, the user is not directly connected to closed user groups, as implemented in the the Internet, although to the user it appears as UniLINK protocol. Using this system, users if he is. The gateway actually executes the are assigned to one or more user groups. Eth­ user commands. The gateway can also exam­ ernet data from one bridge or brouter can only ine the source and destination address and be read by another bridge or brouter if it is a commands entered. A user accessing the member of the same user group. This system Internet must pass an authentication process allows multiple users to share the same RF to gain access through the gateway. The channel, but operate as if they are on different gateway can also be set up to prohibit a user networks, essentially creating multiple logical from using certain commands which could networks on one physical network. Schools pose a security risk to the organization. could be on one logical network; hospitals, medical centers, and doctors' homes on an­ Tunneling other, and a business and its telecommuting employees on a third. One risk to firewall security is the prac­ tice of tunneling. Tunneling can have positive Filtering, Authentication, and Scrambling uses, or can be used to circumvent security. Tunneling refers to the practice of encapsulat­ Security is also provided in a community ing a message from one protocol in another, Ethernet network via features such as IP ad­ and using the facilities of the second protocol dress filtering, traffic type filtering, broadcast to traverse some number of network hops. At and route filtering. In addition, built-in se­ the destination point, the encapsulation is curity features, including user authentication stripped off, and the original message is rein­ and passwords are provided to prevent tam­ jected into the network. In a sense, the packet pering with the cable TV receive and transmit burrows under the intervening network nodes, frequencies. viii The fact that the data is and never actually sees them. There are many modulated using QPSK and the data is uses for such a facility, such as encrypting scrambled using changing seed patterns links and supporting mobile hosts.ix means that it would be extremely difficult to decode.

1995 NcrA Technical Papers -406- REGULATORY ISSUES COMPARISON OF INTERNET ACCESS OPTIONS The legal and regulatory environment in the cable and telco world, coupled with the The term "Internet access" is often used growth of data networks like the Internet, has as if there is only one type of access available. created the need for major reform in tele­ In fact, Internet access runs the gamut from communications policy in the US, Canada, low speed dialup access to high speed dedi­ and countries around the world. The regula­ cated network access. Below are some of the tory environment is politically complex, and primary alternatives.xi the need to relax existing cable and telco regulations in order to build a global informa­ Dedicated Access tion infrastructure is recognized. Dedicated access is appropriate for insti­ The Internet, on the other hand, is cur­ tutions and businesses who want to be hooked rently unregulated. This is in keeping with up to the Internet. For dedicated access, the the fact that common carriers are considered user needs: natural monopolies, and therefore are regu­ lated, but services provided over common • a dedicated leased line (56 kbps or faster) carriers are not. This regulatory policy is not • a router consistently administered, however, since services provided over telco lines are regu­ This kind of connection in the US costs at lated. This has caused some public interest least $2,000 initially, with monthly fees groups to call for similar regulatory require­ starting at $1 ,500 per month to much higher ments for the Internet. charges as line speed increases. Dedicated ac­ cess allows all computers, and all users on a The issue of universal access is also inte­ Local Area Network (LAN) to connect to the grally tied to the debate over regulation of the Internet through the router. It allows users ac­ Internet. The concern is that the Internet not cess to the full functionality of the Internet. create a society of "haves" and "have nots" on Because of the cost of a dedicated connection, the global information infrastructure. The this is not a practical option for home users. current thinking is that a certain level of "basic service" should be available to all citi­ SLIP and PPP zens for a modest fee. But the debate rages on as to what defines "basic service" and how to A less expensive option is to use standard subsidize such universal access.x phone lines and high-speed modems, and connect to the Internet using the Serial Line Given the high "public good" quotient Inter-net Protocol (SLIP) or Point to Point that such networks bring to municipalities, Protocol (PPP). For dial-up access, the user schools, and the general citizenry, in addition needs: to businesses and for-profit enterprises, it is unlikely that government regulatory agencies • SLIP or PPP software will regress into imposing a stricted-regulated • a high-speed modem (V.32 or higher) environment that would hinder the growth of the national information infrastructure. With SLIP and PPP, the user has full ac­ cess to Internet resources, but saves on the high connection costs of a dedicated leased

1995 NCTA Technical Papers -407- line. With these options, the user is actually user may not be able to access all Internet "on the Net", as opposed to accessing it services, and is dependent on the service pro­ through another system. They are suited to vider for services and disk space. The user connecting an individual or home user to a may also have to pay the phone charges, if larger LAN, which has dedicated access to the 800 numbers or local access numbers are not Internet. This solution is not appropriate to provided. connect a network of any size to the Internet, due to the line speeds. The cost of service is typically $20 to $40 per month, (possibly with some additional per­ The connection to the Internet is provided by hour access fee). The cheapest rates apply if a national or regional access provider. A you contract for "off peak" service only (i.e. provider like PSI or UUNET charges about nights and weekends. $250 per month for unlimited SLIP or PPP service; alternately, there may be a lower Cable TV Internet Access monthly charge, with an additional hourly fee. Service providers may supply 800 numbers or The advantage to the user of accessing the local access numbers in major urban areas to Internet via cable TV is that he does not need minimize telephone costs. his own leased line in order to get high-speed 10 Mbps access to the Internet. In the past, Dial-Up Access these speeds, since they required a dedicated leased line, were out of reach for all but large The low-end option for Internet access is corporations. By connecting businesses, insti­ a simple dial-up connection to a computer tutions, municipal offices, and home users which has dedicated access. For dial-up ac­ into a community wide network over cable cess, the user needs: TV, performance can be improved by three orders of magnitude while cost is reduced. • a terminal emulation package • amodem COMPARATIVE INTERNET ACCESS SCENARIOS In this case, the user is not really "on the Net". The advantages are the it is cheap and This section depicts several typical Inter­ easy to set up. The disadvantages are that the net access scenarios and compares and con­ trasts them with Internet access via cable TV.

Source: Data Communications. Aprll1994

Figure 1 - Corporate Connectivity to the Internet 1995 NCTA Technical Papers -408- Committed information rates (CIRs) - the maximum average speed of the connection - Telco Models range from 56 Kb to T 1. PSI's prices start at $400 a month and extend to $3,400, depending One typical method for corporate con­ on management and equipment. Sprint offers a nectivity uses a router and Data Service Unit zero-CIR service (no maximum average speed) (DSU) to tie directly into an the Internet that allows for bursts of traffic at up to T 1 for Service Provider's network. A methodology a flat rate of $400 per month.xv called frame relay can also be used for this purpose. Figure 1 shows a typical scenario for The Cable TV Models connecting corporate users to the Internet. In this scenario, the remote or home users can There are multiple alternatives for the log on via modem and dial-up linexii configuration of Cable TV networks which offer Internet routing. Typically, corporate users access the In­ ternet via leased lines. The company buys one or more leased circuits that connect one or more routers at the customer premise to a router at the Internet service provider's site. Available line speeds range from 56 Kbps to 45 Mbps (T3). The Internet service provider may supply the router at the customer site.xiii

Pricing for such services vary. One Inter­ net service provider, Uunet's Alternet, has pricing which begins at $795 per month for a local 56 kb link, T 1 starts at $1,250 per Figure 2 • Multiple IP Networks on a Cable Network month.xiv

One key point is that the customer, and Figure 2 shows multiple IP networks on a not the Internet service provider, is responsi­ cable network connecting to the Internet using ble for procuring the leased lines. Internet brouters. In this scenario, there are multiple IP Networks on each cable network. Another option that may be used by small This is a practical scenario for a community companies, who do not need the high band­ which includes multiple IP addresses which width that leased lines provide, is frame re­ requires IP routing with cable TV connectiv­ lay. PSI and Sprint, for example, offer frame ity. In this scenario, each site could have its relay services. In this scenario, users need a own IP network, and each would have an In­ router with a frame relay interface and leased ternet Brouter. Each site would have its own line to the Internet Service Provider's point of IP address space, and its own IP administra­ presence (POP). In this case, unlike leased tion. The security firewall would be at the lines, customers only pay for the bandwidth brouter at each site. This scenario would al­ they actually use. low for increased security, ease of manage­ ment and administration, expansion (the abil­ PSI's Interframe includes a router and ity to add more sites/IP networks), plus free­ frame relay DSU installed at the customer site. dom and ease of communication.

1995 NCTA Technical Papers -409- A second scenario is having a single IP network on each cable network, as depicted in Figure 3. In this configuration, the entire ca­ ble TV network using the bridges will be a single IP network. In this scenario, all sites would share the same address space, and would have common IP administration. The security firewall would be at the single router entry point, and there would be no IP firewalls between sites.

This implementation might not be practi­ cal for a city with multiple businesses and institutions using the same network, and Figure 3 - Single IP Network on Each Cable Network would require coordinated management of IP addressing for all of the users. terface) fiber ring, which connects four headends. Connected to each headend is a Ultimately, in a third scenario, multiple community Ethernet network, comprised of cable TV networks could be connected to­ one to three companies. Each company site gether as an IP network over a WAN, via a itself houses its own LAN, which may be long distance carrier such as MCI or AT&T, comprised of hundreds of users. Bridges are or a Competitive Access Provider (CAP) such used to connect the LAN sites to the com­ as Teleport. In this scenario, the Cable TV munity network. networks could either be bridged or routed. The physical media in the network in­ CASE STUDIES clude dedicated fiber in the backbone, shared AM fiber for the headend trunks, and coax. Electronic Commerce Network ECnet - The fiber ring is supporting distances as great Phoenix, Arizona as 36 miles between headends, while the longest fiber/coax headend trunk extends over ECnet was one of the first data networks 15 miles to a customer site. The network op­ set up over cable television. The network was erates downstream at 336-342 MHz, and up­ developed as a collaboration between Times stream at channel T8 (11. 7 5 MHz - 17.7 5 Mirror Cable Television, Digital Equipment MHz).xvi Corporation, and Arizona State University. ECnet connects together manufacturing com­ Access to the Internet is provided by Ari­ panies in the Phoenix area for the purposes of zona State University. Security is provided concurrent Computer Aided Design (CAD), which includes 24 hour/7 day monitoring, file video conferencing, electronic whiteboarding, encryption, protocol monitoring, automated and access to the Internet. Companies using alerts, and lockouts. xvii the network include McDonnell Douglas, Tempe Precision Aircraft, and Modem In­ Hawaii Public Schools struments. The Hawaii public school district in­ The backbone of the ECnet network is a cludes 360 schools located on six islands. 100 Mbps FDDI (Fiber Distributed Data In- This unique geography has perhaps contrib-

1995 NCTA Technical Papers -410- uted to the Hawaii Department of Education HOW TO SET UP A COMMUNITY being on the leading edge of networking tech­ ETHERNET TO INTERNET NETWORK nology. Setting up a cable television network for Oceanic Cable, a Time-Warner subsidi­ Internet access involves both business and ary, Digital Equipment Corporation, and Con­ technical issues. To begin, a business case vergence Systems, Inc., a Digital reseller, must be completed, and the scope, schedule, have collaborated on the Hawaiian school and budget for the network must be defined. network. A project team, project manager, installation team, and site contact for each site must be The Hawaiian schools original network identified, and a project plan prepared. consisted of a T3 (45 Mbps) microwave back­ bone, 28 Tl (1.5 Mbps) leased lines, which didn't meet the needs of the school system. Network Planning and Design "Leased lines are expensive and they don't really provide us with the bandwidth we need The next step is the network design and for the applications we'd like to run on the network map. The design must include net­ network. We needed a high-bandwidth, high­ work layout, site locations, amplifiers, chan­ speed network. With the telephone company, nel assignments, network components, leased that would have meant a Tl line for every lines, etc. school, which would have been very expen­ sive", said Kyunghak J. Kim, director of net­ The basic requirements to set up a com­ work support services for the state of Ha­ munity Ethernet to Internet network are: waii's department of education.xviii • one forward and one reverse channel Hawaiian schools are using the Internet • one bridge or brouter per site for collaborative learning with schools on the • one translator at the headend (not required mainland, accessing images from weather for a dual system) services, maps, and information from libraries • diplexors (either sub-, mid-, or high-split) and universities. "The main thing Channel­ • an Internet point-of-presence (i.e. access Works™ has provided students is the ability to to a backbone router on the Internet) either effectively communicate with other students via one of the user sites on the network, or in other parts of the country and the world, via the headend and the capability to access resources avail­ able in other places," comments Kim. The Several decisions need to be made during ChannelWorks solution has sped up Internet the network planning phase, including: access considerably at Hawaii's schools: sending a message from the University of 1. Which sites will be in the same Closed Hawaii to the mainland and back can now be User Groups? completed in seven or eight seconds - which 2. Which sites will be on the same IP net­ is 100 times faster than what was possible on work? phone lines. xix 3. What are the security and firewall re­ quirements, and where should firewalls be located?

1995 NCTA Technical Papers -411- 4. Where will the connection to the Internet recommended to make sure there is no time­ be located? Will it be in the headend or at related ingress on either channel. a user site? 5. If the Internet connection will be at the Network Installation headend, who will install and manage the connection? When the above steps are completed, the 6. Who will procure, assign, and manage the sites are ready for the installation of the net­ IP addresses? working equipment. At this phase, a back­ 7. Who will secure the leased line connec­ bone router and a leased line are installed at tion to the Internet Service Provider? the headend, if required: What line speed is required? How much will it cost? How will it be paid for? Network Management 8. Who will manage the data network? 9. Who will supply help desk support? What Network management may be supplied is the problem reporting procedure? What by the cable operator or a third party. As a are the service hours? What are the prob­ network grows in size, so does the need for lem escalation procedures? network management. The plans for network 10. What is the monthly service charge? What management should be put in place during the are the billing procedures? planning and design phase.

The services of an Internet consultant or CONCLUSION Internet Service Provider, particularly one who is familiar with cable television, may be The capacity of the Internet will continue helpful during the network planning and in­ to grow, as will the user systems connecting stallation phase of the project to help answer to it. Multimedia and client-server based these questions and devise the network plan. applications, such as digital libraries, telecol­ laboration, concurrent engineering, and As early as possible in the project plan­ visualization will proliferate. Multicasting, ning, a certification of the cable plant should taking video or audio material, digitizing it, be done. The certification of the cable plant is and sending it over the Internet, will benefit an important first step. A detailed checklist is greatly from cable. Videoconferencing over used to ensure that all requirements are met so the Internet to the home PC or to the desktop that the network will function properly.xx will become possible. Cable TV can make high speed access to the multimedia Internet The first requirement for the network is of tommorrow a reality today. that one forward and one return channel must be allocated for the network. The transmit frequency range is 10 to 174 MHz. The re­ ceive frequency range is 54 to 550 MHz. The plant must be two-way, with two-way ampli­ fiers installed and activated, drops must be installed to all sites, and the channels to be used must have no ingress, extraneous carri­ ers, or other signals in either channel. At this phase a 24-hour sweep on both channels is

1995 NCI'A Technical Papers -412- Author References Lynn Jones Community Multimedia Networking, Jim Albrycht - Digital Equipment Corporation 1994 550 King Street, LKG1-2/L07 LANcity Product Architecture, Data Over Cable TV, Littleton, Massachusetts Rouzbeh Yassini ;The Internet Domain Survey, January 1995. Number 01460-1289 of users is an estimate. Note that Internet statistics are always open to debate due to differing measurement Internet Address: [email protected] criteria. They also are, due to the nature of the Internet, Telephone: 508-486-5681 already out of date by the time they are printed. Fax: 508-486-5511 ;;The Internet, Douglas E. Comer, Prentice Hall, 1995 ;;;Net-Cerfing, Richard Karpinski, Telephony, January 31, 1994 iv "ChannelWorks Internet Brouter- Sales Update, Trademarks Lynn Jones, Digital Equipment, May 1994 •IEEE 802.14 Cable-TV Functional Requirements and UniLINK is a registered trademark of LAN­ Evaluation Criteria, (Draft), February 6, 1995 vi"The Digital Channel Business Plan" - Lynn Jones, city Corporation. Digital Equipment, October 19, 1993 vii"The Internet: Corporations Worldwide Make the ChannelWorks is a registered trademark of Connection", Data Communications, April 1994 Digital Equipment Corporation. viiiChannelWorks Internet Brouter Fact Sheet, Lynn Jones, Digital Equipment, May 1994 ixFirewalls and Internet Security - Repelling the Wily Hacker, Cheswick, William R., and Bellovin, Steven M., Addison-Wesley 1994 xThe Economics of the Internet, MacKie-Mason, Jef­ frey K., and Varian, Hal, Dr. Dobb's Information Highway Sourcebook Winter 1994 xiThis section is largely taken from The Whole Internet, Krol, Ed. O'Reilly & Associates, 1993, Appendix A, which contains an excellent comparison of traditional options. xii "The Internet: Corporations Worldwide Make the Connection", Data Communications, April 1994 xiiilbid xivlbid xvlbid xviTimes Mirror Commercial Net Experiment, Martin Weiss, SpecTechnology, March!April1994 xviilbid xviii "ChannelWorks: Digital's Onramp to the Infonna­ tion Highway ... For Subscribers", Digital Equipment Corporation, February 1995 xixlbid xx This section excerpted and summarized from Certifi­ cation Overview", Bill Zabor, Digital Equipment, June 1994

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