Measurements of network performance determine values such as the throughput, latency, jitter and error rates over a network connection. The measured values are used, among other things, for network optimization, error detection and troubleshooting, and for assessing the performance of network infrastructures.
iPerf has become established as a free program for generating and evaluating data streams over data connections. An iPerf server daemon receives TCP and UDP streams and measures the throughput for the corresponding applications along with the latency, jitter, packet loss and packet reordering over UDP connections.
To conduct a bandwidth measurement between two hosts, you start the iPerf server on one device and the iPerf client on the other one. The iPerf client then connects to the iPerf server. The server and client exchange data packets for a certain time or a certain amount of data and generate statistics about this. These statistics provide information about the quality of the connection between the two devices.
When measuring the quality of the TCP connection, the iPerf client transmits completely filled TCP data packets at the fastest speed possible. The average data rate of successful data transfer ("goodput") is the result of what the iPerf server received correctly.
When measuring UDP connection quality, the iPerf client transmits data over a specified bandwidth (1 Mbps by default), although this is without flow or performance control. The "goodput" relates to the maximum bandwidth with which the client's transmission buffer remains permanently filled without data packets being lost.
LANCOM devices include an Iperf2-compatible feature that directly measures the network performance between network nodes such as routers, VPN gateways, and APs. This makes it easier to measure the data throughput over WAN connections or WLAN point-to-point links, for example.
