DoS – first-hand experience

Today at work, we had a first-hand experience of a DoS attack. Around lunch time, internet access was at first sluggish and then dried up completely. TelstraClear, the university’s ISP, seems to have a system that prevents such DoS attacks. I wonder, whether the uni already such a service in place or whether they are thinking now about installing such a system now as well. Interesting to know who was behind that attack: a disgruntled student, a former staff that lost his/her job due to the current restructuring here at uni, or another, unrelated third party?