“The source of Bradham’s difficulties is a feud between two big backbone Internet companies–the long-haul networks that most consumers and even most businesses ordinarily have little to do with. One of these companies, Level 3 Communications, has cut off direct communications with rival Cogent Communications, causing many of each company’s customers to lose access to potentially significant swatches of the Net.”
Blackout shows Net’s fragility | CNET News.com