OSI Reference Model

Application Layer: End user processes like file transfer, e-mail, network software services. E.g. Telnet, FTP

Presentation/Syntax Layer: Format, Encrypt data to send across network.

Session Layer: Establishes, manages and terminates connections between applications .

Transport Layer: End-to-end error recovery, flow control.

Network Layer: Switching, Routing, Addressing, internetworking, error handling, congestion control and packet sequencing.

Data Link Layer: Encoding, decoding data packets into bits.

Media Access Control Sub-layer: Data access/transmit permissions.

Logical Link Sub-layer: Frame synchronization, flow control, error checking.

Physical Layer: Conveys the bit stream (electrical, light, radio)
E.g. Ethernet, RS232, ATM