Editing Network performance (section)

===Latency===
{{Main|Latency (engineering)}}
The [[speed of light]] imposes a minimum propagation time on all electromagnetic signals. It is not possible to reduce the latency below

:<math>t=s/c_m</math>

where s is the distance and c<sub>m</sub> is the speed of light in the medium (roughly 200,000&nbsp;km/s for most [[optical fiber|fiber]] or [[electrical cable|electrical]] media, depending on their [[velocity factor]]). This approximately means an additional millisecond [[round-trip delay]] (RTT) per 100&nbsp;km (or 62&nbsp;miles) of distance between hosts.

Other delays also occur in intermediate nodes. In packet switched networks delays can occur due to queueing.