We have a 105 pipe but it's being hammered pretty hard right now. Historically we see this kind of bandwidth saturation for the first few hours as people setup and they pull down updates they did not do before coming to the LAN and/or download games from Steam they may have just purchased to play at the LAN, plus throw in the CODBLOPS2 free weekend...it adds up pretty quickly.
Here's the last six minutes of WAN traffic to understand:

In total we've pulled down over 76GB of traffic from the web since the doors opened at 6:00 (that's just a little over two hours).
Hopefully. In the meanwhile.....I will update Steam :D
Yep....that's part of the problem
