Page "Internet backbone" Paragraph 12

The government of Egypt shut down the four major ISPs on January 27, 2011 at approximately 5: 20 p. m. EST.

Evidently the networks had not been physically interrupted, as the Internet transit traffic through Egypt, such as traffic flowing from Europe to Asia, was unaffected.

Instead, the government shut down the border gateway protocol ( BGP ) sessions announcing local routes.

BGP is responsible for routing traffic between ISPs.