Goodput: throughput measurement of data speed that does not include retransmissions.

Throughput is a measurement of data transfer speeds over a particular medium, i.e. the internet or a LAN network.

However, in calculating this, it must be taken into account that some information will be retransmitted.

This happens because as the information travels, it hits snags and errors, and gets sent back to be checked and sent again by the network.

Throughput measures these anomalies, thus making the speed appear slightly larger.  Goodput, on the other hand, only measures the original data, and ignores the retransmissions.

In this way, it is always shorter than the throughput. Calculating goodput is easy enough: simply divide the size of a file by the time it takes to transfer from one connection to another.

The difference between the goodput and throughput depends on the size of the file and the status of the network.

The calculation of goodput does not include additional information, so in cases where a file larger than a connections MTU (maximum transmission unit) is sent, it is broken down and each section sent is sent with a header.

In such cases, the goodput and throughput will be close.  However, if the network is congested or requires verification that packets have been received, the throughput will be far larger than the goodput simply because of the extra transmissions that must be performed.

Simply note that as more overhead is added, the difference between goodput and throughput increases.

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