iperf - A TCP, UDP, and SCTP network bandwidth measurement tool
Winsock Packet Editor - WPE Pro is a packet editor.
TamoSoft Throughput Test - TamoSoft Throughput Test is a utility for testing the performance of a wireless or wired network.
Scapy - Scapy is a powerful interactive packet manipulation program.
netperf - Netperf is a benchmark that can be used to measure the performance of many different types of networking. It provides tests for both unidirectional throughput, and end-to-end latency. - HewlettPack...
packeth - packeth is GUI and CLI packet generator tool for ethernet.