How many petabytes do you have?

Level 3 Communications announced Tuesday that it is now carrying 3.0 petabytes, or quadrillion bytes, of Internet Protocol traffic daily, or the equivalent of transmitting the entire Library of Congress print collection more than 300 times a day.

That could make Level 3's IP network that largest by a U.S. carrier. AT&T carries a daily load of 4.411 petabytes per business day, or the equivalent to transmitting the printed contents of the Library of Congress every 3.6 minutes. But that includes both its IP and traditional circuit-switched voice networks, according to a spokesman. AT&T's IP network carries about 2.47 petabytes per day.

MCI declined to discuss traffic volume, citing lack of industry standards for such comparisons, and Sprint’s numbers were not available.

Level 3 officials attributed their company’s traffic growth to its wholesale business, supporting service provider customers including AOL, Comcast, Charter, Net2Phone, Skype, Speakeasy and more.

“Traffic on our network continues to grow faster than the broader Internet market, driven largely by consumer demand for Internet-based services from our cable, content, carrier, ISP and wireless customers,” said Gordon Boyes, vice president of Network and Internet Services for Level 3. “We believe that Level 3 operates an unparalleled, technologically advanced network that’s distinguished by its reliability, broad geographic reach and the ability to quickly scale to meet customer demand.”