Having trouble accessing a favorite Web site? Perhaps the site was taken offline, or the computer hosting it is down for maintenance. However, the cause could be something more mysterious. At any given moment, a portion of Internet traffic ends up being routed into information “black holes.” These are situations where advertised paths exist to the destination, but messages – a request to visit a Web site, an outgoing e-mail – get lost along the way.
Hubble is a system that operates continuously to find persistent Internet black holes as they occur. Hubble has operated continuously since September 17, 2007. During that time, it identified 892,612 black holes and reachability problems. In the most recent quarter-hourly round, completed at 19:40 PDT, 04/13/2008, Hubble issued 73,139 traceroutes to 3,207 prefixes it identified as likely to be experiencing problems (of 78,772 total prefixes monitored by the system). Of these, it found 2,099 prefixes to be unreachable from all its vantage points and 1,029 to be reachable from some vantage points and not others. Below the following map, you’ll find instructions on interpreting and navigating this page. Source : University of Washington