Network Protocols

The seven-layer OSI model for network communications splits communications process into seven separate layers:

Name	Function
Application	Topmost layer, provides users a means to access network resources (only level seen by end user)
Presentation	Transforms data received into a format that is readable by the application layer. Handles encryption/description for secure data
Session	Manages communication sessions between computers. Manages connections with other devices. Half-duplex or full duplex.
Transport	Provide reliable data transport services to lower layers.
Network	Routes data between physical networks. Handles addressing, via IP. Handles packet fragmentation and error detection. Router level. Most complex layer.
Data Link	Transports data across a network. Provides addressing scheme to identify physical devices, bridges, switches, MAC addresses.
Physical	The physical medium for the network communication signals.

Different nodes or computers on the network are only connected at the physical level.

Network Architecture