DDoS mitigation with BGP communities

[Matthew Crocker <matthew () crocker com>]

Hello,

 I just experienced my first official DDoS attack against my network.  
I never realized how helpless I was :(.   I had roughly 70 mbps of 
traffic aimed at one IP.  The IP wasn't even in use,  I'm assuming 
someone typed the wrong IP and meant to send it somewhere else.  I shut 
it down by removing the /24 announcement.   This was fine except for 
the customers on that /24.   I know my upstreams have special 
communities I can set via BGP announcements that effectively say 'route 
packets to this network to null0'.   My question is,  what do I need to 
put on my router (i.e. code examples) to inject the /32 into the BGP 
announcements.   I try to be a good net citizen and announce aggregate 
blocks.  I had to break my /21 up so I could announce everything but 
the /24 in the middle.  Any help would be greatly appreciated.

Routers are a couple 7500 series running 12.0.xx


-Matt