TTCP (Test TCP, see www.netcordia.com/resources/tools.asp) gets a large number of hits on our web site. It is a free throughput testing program that has been used for many years. I obtained it from someone at Excelan, a network interface card vendor, while working at the US Naval Academy in the mid-1980s. I don’t know who wrote the initial version. I was working on PDP11 Unix and needed a testing tool that wasn’t limited by disk I/O bandwidth, which is the problem with using something like FTP for testing. I, along with Mike Muuss, modified TTCP to incorporate other features like UDP testing. [Note: Mike worked at the Ballistic Research Lab, Aberdeen Proving Grounds and was the author of the original version of Ping, the network round trip and reachability test tool - see ftp.arl.mil/~mike/ping.html.]
I shared the modified version with other people, some of whom made other improvements (see the source file header comments for who did what). Later, at Chesapeake Computer Consultants, I created a Java version, which ran surprisingly fast. (See The Network Monitor, www.netcordia.com/resources/network-monitor.asp, issue 3-2.)
TTCP sends or receives a data stream from in-memory buffers, so there is no disk I/O to limit its throughput, making it a useful tool for checking network throughput. Cisco has incorporated it into IOS (see The Network Monitor, www.netcordia.com/resources/network-monitor.asp, TNM 3-1). [While writing this, I realized that a useful extension would be to add the ability to set the DSCP value of the packets.]
TTCP has been a true community development and has been widely used. It is heart-warming to find someone using it for network testing.
-Terry