NetPIPE is a protocol independent performance tool that encapsulates the best of ttcp and netperf and visually represents the network performance under a variety of conditions. By taking the end-to-end application view of a network, NetPIPE clearly shows the overhead associated with different protocol layers. Netpipe answers such questions as: how soon will a given data block of size k arrive at its destination? Which network and protocol will transmit size k blocks the fastest? What is a given network's effective maximum throughput and saturation level? Does there exist a block size k for which the throughput is maximized? How much communication overhead is due to the network communication protocol layer(s)? How quickly will a small (< 1 kbyte) control message arrive, and which network and protocol are best for this purpose? For a paper fully describing NetPIPE and sample investigation of network performance issues using NetPIPE, see the homepage. WWW: http://bitspjoule.org/netpipe/