Smurf attack:

 A maliciously sent ping request to an Internet broadcast address, where it can be replicated up to 255 times. Since the attacker's address appears to be the address of the victim, all ping request replies come to the victim's address instead of the real sender's address. A single attacker sending thousands of these ping messages per second can bring an entire ISP network down by filling its T-1 or T-3 with ping replies. .The Computer Emergency Response Team at Carnegie Mellon University said Smurf attacks went up from 3 percent of reported incidents in January 1998 to 10 percent by December 1998