DOS attack tracing

Hi, We recently experienced several DOS attacks which drove our backbone routers CPU to 100%. The routers are not under attack, but the router just couldn't handle the traffic. There is a plan to upgrade these routers. One criteria is the ability to track which IP address is under attack and blackhole the traffic quickly. Anyone can share your experience of what kind of router is capable of doing this? Also besides having a powerful router which can handle large volume of traffic, is there any other things that we need to consider in selecting the routers? Thanks, Richard