Banner SureCross DX80 Wireless Networks - Manual (Page 10)

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DX80
Reference Guide
Network Basics
The OSI Seven Layer Model
The Open Systems Interconnection (OSI) seven layer model attempts to describe network communication
protocols as a layered series of steps necessary to transmit information between dissimilar devices or
networks .
The lowest level of the model is the physical level and pertains to the actual transfer media (air, wires),
connector types, voltages, and signaling speeds for a specific type of network. Layers two and three also
deal with data transfer at the hardware level .
Layers four through six typically are involved with data addressing - getting the data to the proper end
location .
The seventh and highest level of the model is the application layer . The application layer is the interface
between the user and the network .
Between each layer are protocols translating the information from one layer to the next . The OSI seven layer
model only loosely applies to most communications protocols because several layers may be combined
together, especially the layers involved in TCP/IP communications protocols used in the Internet.
The acronym TCP/IP refers protocols used in the network level (IP) and the transport level (TCP) . The TCP/
IP layers control how sessions are established, error corrections, and other data transportation issues and
encompass multiple layers of the OSI model .
In the Internet example, the application layer includes the protocols for http (Internet
website access), smtp (e-mail), and ftp (file transfers) to name just a few.
The networking term “stack” has been used to describe the seven layers. Data must
move up and down the same stack to be interpreted correctly .
Physical
Data Link
Network
Transport
Session
Presentation
Application
Media Layers
Host Layers
OSI Seven Layer Model
Physical
Data Link
Network
Transport
Session
Presentation
Application
Media Layers
Host Layers
http, smtp, ftp
10 Base-T
TCP/IP
Ethernet
OSI Seven Layer Model - Internet