The Internet Under Crisis Conditions Learning from September 11 (2003) / Chapter Skim
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2 The Network Experience
2 The Network Experience
Pages 21-39
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From page 21... ...
Then the South Tower collapsed, damaging equipment and circuits in the Trade Center complex. The subsequent collapse of the North Tower, the collapse of World Trade Center Building 7 (a 47-story structure)
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From page 22... ...
However, in a number of instances, data that would inform the committee's understanding of what transpired on and shortly after September 11 were lacking (a detailed discussion of Internet-measurement issues is presented in Chapter 5~. OVERVIEW OF DAMAGE AND IMPAIRMENT The terrorist attacks in New York City caused an immediate disruption in communications within the World Trade Center complex.
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From page 23... ...
These events had several types of effects on ISPs and Internet users, including the following: · Loss of Internet connectivity in the vicinity of the attacks. The effects in New York City were extensive as a result of the catastrophic damage at the World Trade Center site, the large number of nearby institutions, and the important role that New York City plays in the Internet infrastructure.
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From page 24... ...
To be sure, telecommunications facilities operators make provisions for power failures. ISP co-location facilities and telephone central offices contain backup batteries and generators.
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Consequently, in the early morning of September 12, some minor perturbations in Internet connectivity occurred in the New York City area when the backup batteries supplying optical devices ran out of power themselves. Although power problems did not persist beyond the month of September 2001, some longer-term effects may still remain.
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26 1 08,000 En i, Q `~ 1 06,000 c' 1 04,000 1 02,000 THE INTERNET UNDER CRISIS CONDITIONS I I I I I I 1 1 1 1 1 1 1 WTC 2 down I 25 Bway power out I | 25 Bway power back | | Nimda | · · · . 1 1 1 1 8 10 12 Day in September 2001 1 FIGURE 2.1 Number of reachable network prefixes as reported by several BGP core routers from the United States, Europe, and Japan from September 8 to September 22, 2001.
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From page 27... ...
The most significant traffic and routing events occurred several hours after the attacks; they resulted from damage to the Verizon central office at 140 West Street and power failures at the Telehouse 25 Broadway Internet co-location facility. Several of these events are visible in Figure 2.1.
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Copyright ~ 2001 Matrix NetSystems, Inc. http://www.matrixnetsystems.com GMT Sep 9/3 9/4 9/5 9/6 9/7 9/8 9/9 9/10 9/11 9/12 9/13 9/14 9/15 EDT Aug 31Sep 1 Sep 2Sep 3Sep 4Sep 5Sep 6Sep 7Sep 8Sep 9 Sep 11 Sep 13 FIGURE 2.3 Reachability of four representative sets of Internet hosts during 12 days in September, 2001.
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From page 29... ...
One ISP provided workshop participants with detailed information about traffic on its backbone that confirmed the general reports received from other ISPs. The ISP providing the detailed information did not experience any unusual peak traffic loads, delay, or loss within its backbone.
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From page 30... ...
Traffic to news sites jumped threefold on September 11, and queries related to a search for news jumped 50-fold; yet the overall traffic was just slightly lower than normal. Not all ISPs reported lower traffic levels, however.
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There was, however, a DNS problem in South Africa stemming from the loss of connectivity in New York, as described in the following section. SPECIFIC NONLOCAL EFFECTS As noted earlier, the damage around the World Trade Center complex had impacts worldwide.
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As a result, they could not access Internet services (such as Web servers) within the country, despite the fact that there were no physical network disruptions in South Africa itself at that time.
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the specifics about their underlying interconnection structures. These interdependencies can become even more difficult to comprehend in the face of technologies that complicate the basic structure of Internet connectivity, such as virtual private networks, private address realms interconnected using network address translators, overlay networks, firewalls, or transparent proxies.
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From page 34... ...
ISP Cooperation As the events of September 11 unfolded, many Internet service providers took steps to ensure that their networks would continue to run smoothly. Their actions ranged from increasing staff at network operations centers to coordinating with other ISPs to assure connectivity.
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connections, TWC replaced the Internet connectivity with Road Runner cable modem service. TWC also supplied New York City's morgue with New Jersey, Dominguez Hills, California, and Irving, Texas and the switch network resulting from a mass calling event following the terrorist attacks in New York and Washington, D.C.
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From page 36... ...
Apparently the first communications impact outside New York City occurred right after United Airlines Flight 175 struck the South Tower at 9:02 A.M., as the load on some telephone switches in northern New 6"World Trade Center Tragedy: Time Warner Cable of New York City & NY1 News Efforts." Time Warner Cable News Release, September 14, 2001.
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From page 37... ...
However, it appears that difficulties in calling out of New York City may have eased by then for example, AOL recommended that users unable to connect to its New York modem banks with a local number try calling a long-distance access number to get online; this advice apparently worked for many users. At 5:20 P.M., World Trade Center Building 7 collapsed, severely damaging Verizon's 140 West Street central office.
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From page 38... ...
capacity. In Lower Manhattan, full capacity was restored within a week.8 Broadcast Television and Radio Transmission facilities of 9 of the 14 local-area television stations along with those of 5 local radio stations, were lost when the North Tower of the World Trade Center was destroyed.
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From page 39... ...
Broadcasters do not consider this pair of sites adequate, however, for the long term: the Empire State Building does not have enough physical or electrical capacity for all of the broadcasters, and the Alpine tower, by virtue of its relatively modest height and remote location, does not serve as sizable a market as the World Trade Center site did. Efforts are now under way to select one or more permanent transmitter sites that are more suitable.
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