Toshiba e-STUDIO190F, Руководство по обслуживанию

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9.1.2. Protocol
One reason for the popularity of TCP/IP is that no one vendor owns it, unlike the IPX/SPX, DNA, SNA or
Apple Talk protocol suites, all of which are controlled by specific companies. TCP/IP evolved in response to
input from a wide variety of industry sources. Consequently, it is the most open of the protocol suites and is
supported by the widest variety of vendors. One huge advantage of using TCP/IP is that, it is required for
communication over the Internet, thus the Internet can be used as a communication backbone.
TCP/IP was originally designed by ARPANET (Advanced Research Project Agency) in 1969 for the UNIX
operating system. In early 1980, UNIX 4.2 BSD version was released. For more detailed information, an
RFC (Request for Comment) document is available from the IETF (Internet Engineering Task Force) on the
Internet at http://www.ietf.org/.
The Internet protocols do no map cleanly to the OSI reference model. The model for the Internet protocol
suite has four layers. From the illustration below, you can see the approximate relationship of the layers.
9.1.3. Cable
For the network transmission media at the Physical layer on the OSI reference model, there are several
cable categories available. Category 5, 8 wire Unshielded Twisted Pair (UTP) cable is commonly used.
Shielded Twisted Pair cables are also available. The Impedance for the STP / UTP Ethernet cable is 100
Ω
.
Category 3 is also used for the 10Base-T Ethernet.
Category Purpose
1 Voice grade telephone line
2 ISDN
3 10Base-T Token Ring (4M)
4 Token Ring (16M)
5 100Base-TX, ATM (155M)
Layer OSI Reference Model TCP/IP Base Function
7
Application Application This layer embraces functions of the OSI
Session, Presentation and Application
layers. Protocols at this layer provide
network services.
6 Presentation
5 Session
4 Transport Transport Compares to OSI Transport layer.
Enables peer communication between
hosts on the internetwork.
3 Network Internet
Corresponds roughly to the OSI Network
layer. Protocols move data between
devices on networks.
2 Data Link Network
Interface
Corresponds to the bottom two layers of
the OSI model. This correspondence
enables the TCP/IP protocols to coexist
with existing Data Link and Physical layer
standards. This layer is concerned with all
aspects of transmitting and receiving data
on the network.
1 Physical
Comparison of the TCP/IP layers to the OSI model