Yaskawa SmartTrac Ethernet Card - Manual (Page 9)

SMART TRAC Ethernet Card
Technical Manual Smart Trac Ethernet Card Ethernet Basics
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7
Ethernet Basics
Introduction
Ethernet is a low cost, widely used LAN access method. Originally developed
by Intel, Digital (now Compaq), and Xerox, it is an open network standard
(IEEE 802.3).
The Open Systems Interconnect (OSI), established in 1984 by the ISO
(International Standards Organization), divides network functions into seven
layers: Physical, Data Link, Network, Transport, Session, Presentation and
Application Protocol.
Application
Presentation
Session
Transport
Data Link
Network
Physical
Ethernet provides
these layers of the
OSI (Open Systems
Interconnect) model.
TCP/IP protocol on
Ethernet provides
all seven layers of
the OSI model.
Figure 1. Ethernet and the OSI Model.
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The Physical Layer transforms data into bits that are sent across the
physical media.
•
The Data Link layer determines access to the network media in terms
of frames. Its Media Access Control (MAC) sublayer is responsible for
physical addressing.
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The Network Layer routes data through a large network.
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The Transport Layer provides end-to-end, reliable connections, often in
terms of segments.
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The Session Layer allows users to establish connections using
intelligently chosen names in packets.
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The Presentation Layer negotiates data exchange formats, also in terms
of packets.