Testing network performance with NTttcp
NTttcp is a multithreaded, asynchronous application that sends and receives data between two or more endpoints and reports the network performance for the duration of the transfer. It is essentially a Winsock-based port of the ttcp tool that measures networking performance in terms of bytes transferred per second and CPU cycles per byte. Because it can be difficult to diagnose a system's overall performance without dividing the system into smaller subsystems, NTttcp allows users to narrow the focus of their testing and investigation to just the networking subsystem.
Whitepaper and tool
