Syria's Internet connectivity has been completely crippled since the early morning of today (EST).
According to Renesys, all of Syria's 84 IP address blocks are unreachable. The company's traceroutes identified five networks that use Syrian-registered IP space and host Syrian content, but these traces lead Tata Communications and offshore destinations. "[These networks] perhaps [are] not subject to whatever killswitch was thrown today within Syria," Renesys wrote in a blog post.
Akamai confirmed the Renesys report and published a traffic chart that visualizes the sudden traffic drop at 10:26 UTC/GMT.
Arbor networks also documented the shutdown of Syria's Internet with a similar characteristic as the shutdown of the Internet in Egypt in January 2011. Egypt was offline nearly seven days back then.