One of the most effective answers is not "buy a stinkin' Cisco firewall" but rather "buy a stinkin' Arbor"
If you want to survive large scale DDOS you need equipment that can scrub the incoming unvalidated data in real-time and keep up.
Combining Source Based Remotely Triggered Black Holing (RTBH) with uRPF affords you the ability in a sophisticated network to drop a large amount of undesired traffic (especially if it's from simpler DDOS strategies). If you do in fact have the $$/need for the Arbor then inside of black-holing the traffic you send it to the Arbor and let it scrub the packets.