Andrew Blum’s recent book Tubes, describes the way that networks interact with each other. A few interesting examples, the first from page 30:
The Internet Assigned Numbers Authority gives out the prefixes, but anyone can put up a sign pointing the way. And sometimes that does go horribly wrong. In one well-known incident in February 2008, the Pakistani government instructed all Pakistani Internet providers to block YouTube, because of a video it deemed offensive. But an engineer at Pakistan Telecom MegaPath, receiving the memo at his desk, misconfigured his router, and rather than removing the announced path to YouTube, he announced it himself – in effect declaring he was YouTube. Within two and a half minutes, the ‘hijacked’ route was passed to routers across the Internet, leading anyone looking for YouTube to knock on Pakistan Telecom’s door. Needless to say, YouTube wasn’t there. For most of the world, YouTube wasn’t available at all for nearly two hours, at which point the mess was sorted out.”
Another example, discussing “peering”, where one network physically connects to another and what can happen when the process breaks down (from page 123):
In one famous peering de-peering [disconnecting] episode in 2008, Sprint stopped peering with Cogent for three days. As a result, 3.3 percent of global Internet addresses ‘partitioned’, meaning they were cut off from the rest of the Internet, according to an analysis by Renesys, a company that tracks Internet traffic flows and the politics and economics of connection. Any network that was ‘single-homed’ behind Sprint or Cogent – meaning they relied on the network exclusively to get to the rest of the Internet – was unable to reach any network that was ‘single-homed’ behind the other. Among the better-known ‘captives’ behind Sprint were the US Department of Justice, the Commonwealth of Massachusetts, and Northrup Grumman; behind Cogent were NASA, ING Canada, and the New York court system.
Also mentioned in Blum’s book is the brief mention of the URL for Facebook’s peering policy, which is not hidden or behind a password. The screenshot at the top is from that page, including the information needed to connect to its network.