How does the Internet Work



This image is a visualization study of inbound traffic measured in billions of bytes on the NSFNET T1 backbone for the month of September 1991. The traffic volume range is depicted from purple (zero bytes) to white (100 billion bytes). It represents data collected by Merit Network, Inc. Credit: Donna Cox and Robert Patterson, courtesy of the National Center for Supercomputing Applications (NCSA) and the Board of Trustees of the University of Illinois

September 29, 2008
One Sunday afternoon last February, the YouTube Web site disappeared from the Internet. YouTube didn't take it down.
The problem came from Pakistan, when a telecommunications company suddenly began rerouting traffic to and from the Web site into an Internet black hole.
Incidents like this fascinate University of New Mexico (UNM) graduate student Josh Karlin. With a National Science Foundation (NSF) grant, he built and posted an Internet Alert Registry (IAR) that automatically sends an e-mail to registered Internet service providers when there is trouble with traffic in their section of the World Wide Web. The registry is free and any Internet service provider can sign up for the warnings.
How to Subscribe.


Internet - What is Was, What it is, And What it will be.

How it all works

Every computer in the world that is connected to the Internet has an address. Those addresses come from the Internet Assigned Number Authority (IANA). That entity assigns the numbers, but it doesn't police them.

"The IANA has been giving out these addresses for a very long time, and people have lost track of where they've gone," said Karlin. "So, some companies that were given Internet Protocol (IP) addresses have folded or sold them to other companies or broken them down into small blocks and given them out to other people, so nobody really knows what's where."

For instance, the University of New Mexico has thousands of Internet addresses assigned to it. But there is no agency that monitors whether UNM only uses the addresses it has been assigned. So how does any ISP sort out what is legitimate and what is not?

There are dozens of companies that sell services to help ISPs sort out suspicious activity from normal traffic. The IAR will alert providers as well. But researchers are only now trying to figure out how to handle suspicious traffic when it suddenly appears.

Karlin is one of them. He and his advisor, UNM computer science professor Stephanie Forrest, and Princeton University computer sciences professor Jennifer Rexford are working on an improvement to the Border Gateway Protocol. The modification changes preference to allow ISPs to automatically route traffic around a source that makes an unexpected change in routing.