SourceTalk sorts the output of the 'show ip cache flow' and 'show ip accounting' commands on Cisco IOS routers and switches. It can be helpful in finding the source of highest traffic on connections overutilized by legitimate traffic or DoS attacks. To use it, paste the entire output of either command in the input textbox and hit ‘Run’. By default the program will deliver the top 10 talkers in descending order, sorted by the number of packets/bytes sent (taken from the last column of the output). The program processes up to 100 000 lines of traffic data and the results can be saved to a .txt file.
sourcetalk works great