What is the MTU size?

MTU stands for Maximum Transmission Unit. The MTU size essentially describes the maximum possible size of a data packet to be transmitted.

MTU and MTU size:

The MTU size (Maximum Transmission Unit) essentially determines the maximum possible size or length of a data packet that can be transmitted over a transmission system, such as the Internet. Generally, the MTU is limited upward by the network, but may be smaller. But the smaller it is, the greater the fragmentation of the user data to be transmitted in the end.

To illustrate, the upper limit can be compared with the height limit for highway underpasses or bridges. Trucks or cars that exceed this height cannot pass. It is the same with packets that exceed the MTU of a network: They cannot be transmitted. Instead, they are divided into several smaller data units, transmitted in pieces, and reassembled at the destination. It's as if you were to disassemble a vehicle, bring it through the tunnel in individual parts, and reassemble it at the destination.

In addition to the pure data, whose maximum size in bytes is expressed by the MTU size, data packets also contain other meta-data such as the sender and recipient IPs. The recommended MTU size is 1400, since this is internationally compatible with most mobile networks.

The smaller the MTU size, the more individual data packets files are divided into (fragmentation). Since meta data is also transmitted with each data packet, data consumption also increases if a smaller MTU size is configured.