The router is a small box bristling with antennas. Stands on the table near the computer and blinks with multi-colored lights. There is no particular need to know what's going on inside the router. This is an ordinary household appliance, just like a television or a camera. And, like any household appliance, the router has settings that require special knowledge. And if there are no problems with the Internet, then it is better not to touch anything!
What is MTU
Are you familiar with the situation when some sites do not open through a Wi-Fi router? Or is it terribly slow. Or the video on the Internet does not play. Everything "slows down".
The reason for this is often setting up an Internet connection - the parameters of the WAN port of the router. And one of the most critical parameters is MTU.
MTU - maximum transmission unit. The maximum size of the payload data block of a packet that can be transmitted by the protocol without dividing this block.
In fact, everything is simple. Information on the Internet is transmitted in small pieces (packets). An analogy can be drawn with sentences in human speech. The longer the sentence, the more information. But the more difficult it is to transmit it over a long distance.
Can you hear me ?
Imagine that you are shouting to someone across the street. Cars fly by, hum and noise. There and then other people shout from different sides. The longer your phrase, the more likely it is that the other side will not hear everything. We'll have to repeat it several times.
Perhaps it will be faster if you shout in short phrases? Not really. Packages, in addition to the actual data, also contain the service part. The main task of service information is to inform who it is intended for. And the shorter the phrases, the more often you have to transfer additional information. This means that the transmission rate of useful information drops again.
There is no general solution to the problem. Each provider solves it independently. Different providers on the network may have different MTU values.
Dimension problems
It is important that your router has the correct setting for this parameter, which matches the MTU value of your ISP.
The ISP does not know the MTU value for all nodes on the network. It sends packets to everyone the same way. And if your router has a lower MTU value, then it will not be able to receive the entire packet. Then you have to fragment the package.
Everyday situation: you need to move a table from one room to another. In one place the door is wide, and the table was carried through without any problem. But the trouble is, the door in another apartment is too small. The table doesn't go through. You need to disassemble it, bring it in and reassemble it. It will take a lot of time.
From the example it is clear why the network can be slow if the settings are incorrect. It can be much worse. The table cannot be disassembled. Then the site will not open at all.
Only one of the causes of Internet problems has been considered. Other reasons can affect the speed of the network.
