According to the New York Times it was 300 gbps and Cyberbunker was the bad guy.
http://www.nytimes.com/2013/03/27/technology/internet/online-dispute-becomes-internet-snarling-attack.html?pagewanted=all&_r=0
It didn't ask me for an account. YMMV. I suspect you will need cookies.
-Bill
At least they compared it to a traffic jam. 