Did you know there are 4 types of network latency?

Speaking of latency, most of us are familiar with it. High latency will greatly reduce our entertainment experience. For example, you are PKing with your enemy in a game, and suddenly the network slows down. You watch others keep hacking at you, but you can only dodge slowly, and sometimes you can't even move. This experience is really sour.

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For network devices, latency refers to the total transmission time of a frame from the source to the destination, including the processing time of all nodes in the network and the propagation time on the transmission medium. Its calculation method is also very simple. You only need to add timestamp T1 when sending and timestamp T2 when receiving, and then T2-T1 to get the latency of the entire frame transmission, as shown in the figure below:

Delay = T2-T1

This is actually a very easy thing to understand, but it becomes complicated after considering the length of the message.

We all know that a message has a length. So when timestamping, should it be done on the first bit of the message or on the last bit? In order to distinguish between sending and receiving, the delay is divided into four types:

• First In last Out: FILO, first in first out
• Last In Last Out: LILO, last in last out
• Last In First Out: LIFO, Last In First Out
• First In First Out: FIFO, first in first out

As shown in the following figure:

Considering the delay of frame length

In order to measure the latency, the standards organization has a special test item in RFC2544 to uniformly measure the latency of network equipment.

If you want to measure the delay professionally, you need a professional test instrument. For example, the instrument below can measure 4 types of delay, as shown in the following figure:

Professional instrument measurement delay

Friends, please first understand this simple time delay. Only professionals can perform such detailed measurements.