in assessing the state of the Internet during a crisis. However, they are typically considered proprietary and are only available to the operators running a specific network.

MEASUREMENT CHALLENGES

Proprietary Data

As indicated above, business and legal considerations can mean that most data about Internet behavior during crisis conditions may never be made public. If these data were available, the assessment of Internet behavior during a crisis, or indeed, at any other time, would be greatly simplified. There would be challenges in organizing and normalizing the data, but these procedures would readily lend themselves to scientific methods. However, convincing large network providers to make their data publicly available is at best an uphill battle and at worst a pipe dream. An alternative approach would be to mandate reporting by ISPs to an agency such as the Federal Communications Commission (indeed, reports of certain types of outages in the public telephone network must be so filed under present rules).

Consistency in Data and Analysis

There is no guarantee that data gathered at different sites are consistent. Time stamps, units, and field descriptions for data can all be different. Owing to sampling and the possibility of measurement errors, there are also issues of the basic accuracy of particular measurements. Furthermore, even if the data are consistent, the tools and data analysis methods must also be consistent in order to evaluate and validate results.

Representativeness

The heterogeneity of the Internet infrastructure and its users, applications, protocols, and media all render it difficult if not impossible to make representative statements about overall Internet behavior on the basis of a small number of measurements. This heterogeneity manifests itself in several ways, such as:

  • Available bandwidth. Wireless users with a low-bandwidth connection to the Internet exhibit dramatically different behavior from users with corporate high-bandwidth connections. High-bandwidth users are much more likely to access multimedia content such as video streams.

  • Network congestion. The levels of congestion in the Internet vary



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