Tactics for surviving heavy DDoS attack?

[offset <>]

I haven't been able to find any information regarding how to survive a sustained
heavy DDoS attack (ie. greater than 2G/sec) from a providers perspective.  I see
a lot of information on what DDoS is, how not to be an amplifier, etc, but
not much on best practice router/switch configs, hardware/solutions to stay alive
during a DDoS attack, etc.

If you are an ISP, other than calling your upstream provider to null route the
target IP, what other options are available?

-offset