The Origin of TTCP (Test TCP)

Terry Slattery
Principal Architect

TTCP (Test TCP, see 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]

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,, 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,, 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.



Re-posted with Permission 

NetCraftsmen would like to acknowledge Infoblox for their permission to re-post this article which originally appeared in the Applied Infrastructure blog under


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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

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John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.