what's the difference between Transfer, Transport and Transmission as the noun

Solution 1:

From MacMillan:

transfer, v. tr. : to copy information or images from one place or object to another

transport, v. tr. : to move people or things from one place to another, usually in a vehicle

transmit, v. tr. : if a substance transmits light, sound, or energy, the light, sound, or energy can pass through it

FTP is a protocol for transferring files from one computer to another.

The transport layer is the vehicle for moving data. As this site explains, "the transport layer relieves the upper layers from any concern with providing reliable and cost effective data transfer." In other words, the other layers don't have to know how the truck (transport layer) works; they just have to know the truck is there.

TCP allows two hosts to transmit packets; conceptually, the packets pass through the medium of TCP without loss, and without being reordered.

Solution 2:

It is not possible to state absolute and universal definitions of the terms, much less the differences between them.

Transfer, transport and transmission are not confined to Computer Science alone. They are extensively used; defined differently in different fields of science and technology.

Blood is transported through the blood vessels; materials are transported by road, rail, sea and air. Infections are transmitted; power is transmitted in a motor vehicle as well as over electrical lines. In biochemistry, an enzyme type 'transferase' catalyzes the transfer of a functional group from one molecule to another; an employee is transferred from one location to another.

Some attempts could be made to show context-sensitive distinctions, though.