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Open System Interconnection reference model
Open System
Interconnection reference model A network architectural model developed by
International Organization for Standardization (ISO) and International
Telecommunication Union Telecommunication Standardization Sector (ITU-T). The
model consists of seven layers, each of which specifies particular network
functions such as addressing, flow control, error control, encapsulation, and
reliable message transfer. The highest layer (the application layer) is closest
to the user. The lowest layer (the physical layer) is closest to the media
technology. The next to lowest layers are implemented in hardware and software,
while the upper five layers are implemented only in software. The OSI reference
model is used universally as a method for teaching and understanding network
functionality. Similar in some respects to SNA. See application layer, data
link layer, network layer, physical layer, presentation layer, session
layer, and transport layer.
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