What is Latency?
In computer networking, we’re forced by physics to deal with latencies or delays, but we usually don’t think about what latency really is and what causes it.
To start with “latency,” means different thing to different people, even within the narrow confines of computer networking. To telecoms and physical layer folks, latency is about the delay of physical signals. And to applications people, latency is usually considered the elapsed time from when a user requests something, a web page for example, until the action is fully completed. At the IP layer, the one we care about, network latency is the amount of time it takes for a packet to cross between source and destination devices.
There are a number of separate components that create the total delay across the network: