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Introduction

A BRIEF OVERVIEW OF THE INTERNET

The Internet is a worldwide collection of networks, operated by some 10,000 Internet service providers (ISPs),1 that accommodates a diversity of applications such as e-mail, instant messaging, the World Wide Web, and numerous other, more specialized functions.

This system involves multinational telecommunications carriers, cable companies, corporate networks, nonprofit-organization networks, government-agency networks, sole proprietorships, and even hobbyists. Each network consists of a set of optical-fiber, copper-circuit, or wireless communications links that connect to “end-hosts”—desktop personal computers (PCs) or servers that provide Web content—or to specialized computers known as routers that control the paths taken by data packets. The interconnection of these networks is facilitated by a set of standardized protocols that determine how data and routing information are exchanged.

The networks of the Internet are not only interconnected but for the most part are richly interconnected. Its architecture, which dynamically adjusts the routes that packets follow in response to changes in the network (such as failures of communications links), emphasizes redun

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Boardwatch Magazine (<http://www.boardwatch.com>) lists 9,400; CyberAtlas (<http://cyberatlas.internet.com/big_picture/geographics/article/0,,5911_151151,00.html>) puts the worldwide figure at more than 11,400.



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1 Introduction A BRIEF OVERVIEW OF THE INTERNET The Internet is a worldwide collection of networks, operated by some 10,000 Internet service providers (ISPs),1 that accommodates a diversity of applications such as e-mail, instant messaging, the World Wide Web, and numerous other, more specialized functions. This system involves multinational telecommunications carriers, cable companies, corporate networks, nonprofit-organization networks, government-agency networks, sole proprietorships, and even hobbyists. Each network consists of a set of optical-fiber, copper-circuit, or wireless communications links that connect to “end-hosts”—desktop personal computers (PCs) or servers that provide Web content—or to specialized computers known as routers that control the paths taken by data packets. The interconnection of these networks is facilitated by a set of standardized protocols that determine how data and routing information are exchanged. The networks of the Internet are not only interconnected but for the most part are richly interconnected. Its architecture, which dynamically adjusts the routes that packets follow in response to changes in the network (such as failures of communications links), emphasizes redun 1   Boardwatch Magazine (<http://www.boardwatch.com>) lists 9,400; CyberAtlas (<http://cyberatlas.internet.com/big_picture/geographics/article/0,,5911_151151,00.html>) puts the worldwide figure at more than 11,400.

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dancy.2 However, this redundancy has its limits; only a finite number of paths connect any given point to the rest of the system. Also, geography and economics mean that some locations have a high concentration of Internet facilities while others only have few. New York City, a principal focus of this report, can be thought of as a “superconnected node.” This is largely because the city has a great many Internet users, private data networks, ISPs, and fiber-optic grids.3 For example, more than 600 dial-up ISPs and over 300 digital subscriber line (DSL) providers are listed in the ISP directory Boardwatch for the borough of Manhattan alone. Fiber-optic cables enter and exit Manhattan by way of at least five different rights-of-way. At least 74 U.S. and multinational telecommunications carriers have equipment in New York, either in co-location facilities or in private suites. The city is served by more than 100 international Internet carriers, and it has direct links with 71 countries.4 Connected to the Internet through the long-haul fiber networks of several major carriers, New York City is also a major interconnection point for these carriers.5 Interconnection is for the most part done at one of several key “carrier hotels”—buildings in which carriers lease space in order to link with other carriers located in the same building. Internet providers connect with each other through private connections at the carrier hotels, either directly through Internet exchange points such as the New York Internet Exchange (NYIX) or indirectly through transit providers. Most transatlantic telecommunication cables landing along the New Jersey/New York coastline are “backhauled” to one of the Manhattan 2   The redundancy and distributed character of the Internet clearly echo the design contemplated in Paul Baran’s seminal studies of packet networks at RAND. The series, together with brief commentary, is available online at <http://www.rand.org/publications/RM/baran.list.html>. 3   The Lower Manhattan Telecommunications Users’ Working Group (LMTUWG. August 2002. Building a 21st Century Telecom Infrastructure: Lower Manhattan Telecommunications Users’ Working Group Findings and Recommendations) reports six physically distinct fiber networks in Lower Manhattan (AT&T, Con Edison Communications, MCI WorldCom, Metromedia Fiber Network, Time Warner, and Verizon). Information supplied to the committee by Anthony Townsend indicates more than 40 providers of fiber in Manhattan, not all of which are physically distinct (because of sharing and resale by providers). 4   Telegeography, Inc. October 2001. Telegeography 2002: Global Statistics and Commentary. Washington, D.C. Executive summary available online at <http://www.telegeography.com/products/books/pg/pdf/pg2002_exe_sum.pdf>. 5   In addition to New York City, Washington, D.C., stands out on the East Coast of the United States as having a high concentration of Internet facilities. Several Internet service providers maintain network-control and data centers near Washington, D.C., and in Northern Virginia. Thus, in most ISP networks, the New York City-to-Washington, D.C., corridor contains the largest number of circuits.

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carrier hotels to facilitate interconnection with other network operators. In some cases, the only route by which carriers can interconnect with the transatlantic cables is at one of the New York City carrier hotels. Local Internet access may be provided through a number of different technologies, including dial-up, integrated services digital network (ISDN), DSL, T-1, cable modem, wireless, and SONET fiber. Many of these connections take place over the network of the local exchange carrier, Verizon, and the long-haul fiber networks connect to Verizon’s central offices as well. Several ISPs that have registered as competitive local exchange carriers (CLECs) also have equipment in these central offices; collocated equipment there connects their networks to Verizon facilities that in turn connect the ISPs to their customers through DSL or ISDN. Finally, dial-up customers use the Verizon local network to place phone calls to modems operated by their ISPs. Other high-speed local data circuits are supplied by such companies as Time Warner Cable, Frontier, Cablevision/Lightpath, Metromedia Fiber Network, Inc. (MFN), AT&T Local Services, and WorldCom. WHAT WOULD IT MEAN FOR THE INTERNET TO FAIL? There are two principal types of failure that the Internet can incur: Parts of the network, such as interconnection points or communications links, are damaged or destroyed, and consequently the Internet stops functioning as expected. There are two obvious manifestations of this kind of failure. First, the Internet could be damaged enough that it is partitioned—split into separate networks—so that a user might be able to reach some Web sites or send e-mail to some places but unable to communicate with others. Second, the Internet could remain fully interconnected but the damage might cause a reduction in capacity that impairs the network’s operation in a material way. That is, when some links are damaged and new routes are constructed by the network to bypass the failed components, the backup paths are often of lower bandwidth. Thus there is less overall capacity, and increased network congestion is a likely outcome. A user might, for example, experience significantly greater Web-page loading times and be unable to view video clips. Changes in network use result in higher loads that cause parts of the network to be overwhelmed by traffic. For example, increased network use in a particular geographical area could overload the aggregate capacity connecting that area to the rest of the Internet. Or, increased demand on a particular service, such as a Web site, might exceed the capacity of the links to that service or the capacity of the computers providing it.

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Both types of failure—whether or not either of them occurred as a result of the September 11 attacks—are considered in this report. A BRIEF OVERVIEW OF EVENTS ON SEPTEMBER 11, 2001 As the catastrophe at the World Trade Center unfolded, elements of the communications and power infrastructures were impaired, damaged, or destroyed. Box 1.1 provides a detailed outline of what transpired on and immediately after September 11. Local effects, such as damage to Verizon switching centers and last-mile facilities, had direct effects on Lower Manhattan—notably, the loss of telephone lines and damage to the cellular-phone system. At the same time, the infrastructural damage had effects that extended beyond the immediate area. Following is a summary of the key events and their effects on telecommunications, including the Internet: 8:45–10:00A.M. Towers are attacked and set afire. Interior World Trade Center (WTC) communication is disrupted. Increased volume congests local exchanges and wireless networks. Limited physical damage occurs to the surrounding local telephone networks. 10:00–11:00A.M. Towers collapse. Because the WTC was a significant wireless repeater site, some wireless connectivity is disrupted (Sprint PCS, Verizon, AT&T Wireless). Several ISPs’ points of presence (POPs) in the complex—those of WorldCom, AT&T Local Service, and Verizon/ Genuity—are destroyed. Some data and private-line services to a diverse set of customers in New York City, Connecticut, Massachusetts, and even some European locations are disrupted. 11:00A.M.–5:00P.M. Local power failures occur and some equipment is switched over to battery and/or generators. Fires burn in the WTC complex. 5:20–5:40P.M. WTC Building 7 collapses, destroying a Consolidated Edison electrical substation in the process. The collapse also breaches the 140 West Street Verizon central office building, causing damage to equipment and the flooding of basement power systems. The fires, collapse, and flooding knock out much of the telecommunications service in Lower Manhattan. Although there were other significant events on September 11, 2001, this report mainly examines those in New York City. The crash of United Airlines Flight 93 in Somerset County, Pennsylvania, and that of American Airlines Flight 77 into the Pentagon did not appear to have any additional impact on the public Internet’s infrastructure—though they were definitely a factor in shaping how people made use of the network. The

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BOX 1.1 Detailed Time Line of the Events of September 11, 2001, and the Days Immediately Following Date and Time Event Internet Effect 9/11/2001   7:59–8:42 A.M. American Airlines Flight 11, United Airlines Flight 175, United Airlines Flight 93, and American Airlines Flight 77 take off.   8:40 A.M. Federal Aviation Administration (FAA) notifies North American Aerospace Defense Command (NORAD) American Flight 11 hijacked. 8:43 A.M. FAA notifies NORAD American Flight 175 hijacked. 8:46 A.M. American Airlines Flight 11 crashes into North Tower (WTC 1) of World Trade Center. 8:46 A.M. Fighter Scramble Order: two F-15s dispatched from Otis Air National Guard Base in Falmouth, Mass. (airborne 8:52 A.M.). 8:52 A.M. Port Authority Trans-Hudson (PATH) train service ordered stopped. 9:02 A.M. United Flight 175 crashes into South Tower (WTC 2). BBC, CNN, MSNBC, New York Times, Yahoo news, and other news Web sites become extremely unresponsive. Smaller local and regional news sites such as sfgate.com and nando.net still responsive. 9:12 A.M. “Rescue” PATH train departs WTC station.   9:17 A.M. FAA shuts down all New York City airports. 9:21 A.M. All bridges and tunnels in New York City closed.

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Date and Time Event Internet Effect 9:24 A.M. FAA notifies NORAD American Flight 77 hijacked; line kept open; United Flight 93 reported hijacked during same call.   9:24 A.M. Fighter Scramble Order: two F-16s dispatched from Langley Air Force Base, Va. (airborne 9:30 A.M.). 9:32 A.M. New York Stock Exchange closed. 9:37 A.M. American Flight 77 crashes into Pentagon. 9:39 A.M.   All New York City VHF stations, except CBS 2, off the air. Many radio stations also off the air. 9:40 A.M. FAA orders nationwide air traffic halt.   9:45 A.M. Passenger on United Flight 93 makes cell-phone call. 10:03 A.M. United Airlines Flight 93 crashes in Somerset County, Pa. 10:05 A.M. WTC 2 (South Tower) collapses. Verizon (South Tower), Genuity POPs in World Trade Center destroyed, AT&T Local Services POP in sub-basement operating on battery power. 10:10 A.M. Portion of Pentagon collapses.   10:28 A.M. WTC 1 (North Tower) collapses. 10:31 A.M.   Transatlantic circuit reported down after North Tower collapse. 10:32 A.M.   ISP operators report traffic volume decreasing slightly on networks. 11:02 A.M. All New York City bridges opened for outbound traffic only.  

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Date and Time Event Internet Effect 11:12 A.M.   Hundreds of DS-3 circuits reported down in New York City. 11:39 A.M.   CNN.com back up with very low graphics. 1:02 P.M. New York City Mayor Giuliani orders evacuation of Manhattan south of Canal Street.   1:16 P.M.   WorldCom SS7 long-distance switch experiences problems. 2:26 P.M.   AT&T reports its long-distance network is intact, but some equipment was damaged in its local New York service. 3:48 P.M.   CNN.com employs Akamai content server network to increase capacity. 3:48 P.M.   Covad reports service affected by fire in/near 140 West Street central office. 4:35 P.M. Commercial power fails because of fire at World Trade Center Building 7 (built over Consolidated Edison substation); Con Edison reports area bordered by Dover Street on the north, the East River to the east, William Street to the west, and Wall Street to the south without commercial power. 25 Broadway, 32 Old Slip, 140 West Street on generator power. 5:20 P.M. World Trade Center Building 7 collapses. Verizon’s 140 West Street central office walls breached by falling steel beams.

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Date and Time Event Internet Effect 7:17 P.M. U.S. Attorney General Ashcroft announces FBI has set up Web site for tips about the attacks: <www.ifccfbi.gov>.   7:33 P.M. Verizon announces payphones in Lower Manhattan free for local calls. 8:30 P.M. President Bush addresses the nation. 9:54 P.M. Federal Emergency Management Agency notifies primary Emergency Alert System stations by e-mail to “make any and all preparations” if primary communication methods fail (estimated time). 10:07 P.M.   ISP dial-access equipment overheating in 32 Old Slip. Reduction in inbound calls from New York City area. 10:26 P.M.   Generator stopped at 32 Old Slip; some carriers on battery. 10:36 P.M.   Verizon circuits at 60 Hudson Street reported down. 11:21 P.M.   NYC.gov (161.185.0.0/ 16) offline. 9/12/2001   1:09 A.M.   Generator started at 32 Old Slip; Verizon circuits still down. 2:30 A.M.   Sprint reports that power fluctuations at a New York City switching facility disrupted Sprint voice, data, and wireless in southern Connecticut. 9:00 P.M. Incorrect report of structural problems at 60 Hudson Street.  

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Date and Time Event Internet Effect 10:22 P.M.   NYC.gov restored online. Fuel truck allowed into area to refuel 25 Broadway. 9/13/2001   5:38 P.M.   25 Broadway generator failure; some equipment on battery. SAIX (South Africa Internet Exchange), NYIX (New York Internet Exchange), DANTE, Teleglobe, and many other providers affected. 9:28 P.M.   25 Broadway generator repaired. 9:47 P.M.   25 Broadway generator fails (again). 9/14/2001   11:59 A.M.   Fiber cut south of Washington, D.C. (MFN). 8:26 P.M.   32 Old Slip power fails. 8:55 P.M.   32 Old Slip power restored. 11:10 P.M.   25 Broadway restored on Consolidated Edison-supplied generator. 9/15/2001   1:28 P.M.   25 Broadway generator out of fuel; because of misjudged fuel consumption and fuel-truck travel time. 8:03 P.M.   25 Broadway generator refueled.   SOURCE: Compiled from various news reports and reports obtained by the committee from representatives of various Internet service providers.

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destruction at the Pentagon certainly had some effect on military communications, but those are not considered in this report. However, as is discussed in Chapter 2, indirect impacts on Internet operations in the Washington, D.C., metropolitan area were felt as the normal course of business was disrupted.