The following HTML text is provided to enhance online
readability. Many aspects of typography translate only awkwardly to HTML.
Please use the page image
as the authoritative form to ensure accuracy.
BOX 2.1How Damaged Cables in New York City Could Affect the Internet in Other Countries
It may seem surprising that events in New York City could have disrupted Internet connectivity far from U.S. shores, but one explanation is the structure of the international telecommunications market. The pricing and availability of international phone circuits are complex and do not necessarily reflect such simple measures as distance. They do reflect such factors as treaties, other historical ties between countries, and geography. For example, it is often easier to run a cable under water than across land. Also, in many cases, it is much less expensive for an Internet service provider (ISP) in country A to connect with an ISP in neighboring country B by leasing a line to the United States (or, in some cases, to the United Kingdom) than simply by leasing a line that runs directly from A to B. As a result, many regions choose to interconnect their various ISPs in the United States. New York City (and London) are key interconnection points for Africa and parts of Europe. Miami, Florida, is a major interconnection point for Central and South America. It is this counterintuitive interconnection pattern that explains why the collapse of the World Trade Center affected networks in Italy, Germany, Romania, and South Africa.
Traffic Load Across the Internet
Active ping-style probes are used by a number of entities to monitor the Internet. Data from these sources showed only a small loss in overall connectivity during September 11 and a corresponding slight increase in packet delay times and loss. One example, collected by the Cooperative Association for Internet Data Analysis (CAIDA), is shown in Figure 2.4. Measurements such as these reflect a sort of global average, highlighting the fact that from a global traffic perspective, the events of September 11 were actually quite localized in scope.
These observations are supported by passive measurements of packet traffic. Reports of several ISPs that participated in the committee’s workshop indicated that the total level of Internet traffic in fact dropped slightly on September 11 compared with that on the previous Tuesday. The normal Internet pattern, by contrast, is for traffic volume to increase slightly each week.
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. Nor did it report any unusual routing instability there. Impacts were confined to the edges of its network, such as customer-access lines. This view is supported by data from Yahoo, which averaged roughly 1
Items in cart [1]
