In order to measure traffic at higher speeds like ATM OC3 (150 Mbits/s), data capturing can no longer be effectively done on standard UNIX machines using mechanisms as the libpcap library. Therefore, the National Laboratory for Applied Network Research (NLANR) and MCI Telecommunications Corp. have developed OC3MON as a low cost high-speed traffic flow measurement system [14]. OC3MON is part of the ``CORAL'' project, which is now aiming at the development of a similar monitor for even higher (OC12) line speeds.