How is latency calculated?

Answer:

There are 2 ways to calculate latency; Cut through and Store and Forward:

Cut-through (First In First Out, FIFO) - The frame is forwarded through the switch before the entire frame is received. At a minimum the frame destination address must be read before the frame can be forwarded. This mode decreases the latency of the transmission, but also reduces error detection.

Store-and-forward (Last In First Out, LIFO) - The entire frame is received before any forwarding takes place. The destination and source addresses are read and filters are applied before the frame is forwarded. Latency occurs while the frame is being received. Latency is greater with larger frames because the entire frame must be received before the switching process begins. The switch is able to check the entire frame for errors, which allows more error detection.