ABSTRACT
All three lower layers (physical, data, and network) of OSI-RM provide an environment for transmitting user data from source to destination stations across the network. The transmission of user data includes various functions and services such as routing provided by the network layer with every packet received from the transport layer, framing, error control (offered by the data link layer), and sending of frames (provided by the physical layer). After going through these functions, it is then transmitted over transmission media. The user data, as it travels to the network layer, is termed a
packet
, and after the packet is delivered to the data link layer, it is termed a
frame.
