資料來源 : Free On-Line Dictionary of Computing
Open Systems Interconnect
(OSI-RM, OSI Reference Model, seven layer model)
A model of network architecture and a suite of {protocols} (a
{protocol stack}) to implement it, developed by {ISO} in 1978
as a framework for international {standards} in heterogeneous
computer {network} architecture.
The OSI architecture is split between seven {layers}, from
lowest to highest: 1 {physical layer}, 2 {data link layer}, 3
{network layer}, 4 {transport layer}, 5 {session layer}, 6
{presentation layer}, 7 {application layer}.
Each layer uses the layer immediately below it and provides a
service to the layer above. In some implementations a layer
may itself be composed of sub-layers.
OSI is the umbrella name for a series of non-proprietary
protocols and specifications, comprising, among others, the
OSI Reference Model, ASN.1 ({Abstract Syntax Notation 1}), BER
({Basic Encoding Rules}), {CMIP} and {CMIS} (Common Management
Information Protocol and Services), {X.400} (Message Handling
System, or MHS), {X.500} (Directory Service), {Z39.50} (search
and retrieval protocol used by {WAIS}), and many others.
Apart from its actual application to real protocols, it also
serves as a useful teaching model.
(2002-05-19)