(This program was not used in the text, but is a useful tool of which readers should be aware.) ttcp is a benchmarking tool for measuring TCP and UDP performance between two systems. It was created at the U.S. Army Ballistics Research Lab (BRL) and is in the public domain. Copies are available from many anonymous FTP sites but an enhanced version is available from ftp://ftp.sgi.com in the directory sgi/src/ttcp.