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Coaxial Cable

Coaxial cable, referred to as coax, contains a center conductor made of copper that’s surrounded by a plastic jacket with a braided shield over it. A plastic such as polyvinyl chloride (PVC) or fluoroethylenepropylene (FEP, commonly known as Teflon) covers this metal shield. The Teflon-type covering is frequently referred to as a plenum-rated coating, and …

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data network Modulation Techniques

In networks, modulation is the process of varying one or more properties of a waveform, called the carrier signal, with a signal that typically contains information to be transmitted. Modulation of a waveform transforms a baseband (Ethernet or wireless) message signal into a passband signal (a passband [a band-pass filtered signal] is the range of …

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The Physical Layer

the Physical layer does two important things: it sends bits and receives bits. Bits come only in values of 1 or 0—a Morse code with numerical values. The Physical layer communicates directly with the various types of actual communication media. Different kinds of media represent these bit values in different ways. Some use audio tones, …

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The Data Link Layer

The Data Link layer provides the physical transmission of the data and handles error notification, network topology, and flow control. This means the Data Link layer ensures that messages are delivered to the proper device on a LAN using hardware (MAC) addresses and translates messages from the Network layer into bits for the Physical layer …

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The Network Layer

The Network layer manages logical device addressing, tracks the location of devices on the network, and determines the best way to move data. This means that the Network layer must transport traffic between devices that aren’t locally attached. Routers are Layer 3 devices that are specified at the Network layer and provide the routing services …

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The Transport Layer

The Transport layer segments and reassembles data into a data stream. Services located in the Transport layer handle data from upper-layer applications and unite it onto the same data stream. They provide end-to-end data transport services and can establish a logical connection between the sending host and destination host on an internetwork. The Transport layer …

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The Session Layer

The Session layer is responsible for setting up, managing, and then tearing down sessions between Presentation layer entities. This layer also provides dialog control between devices, or nodes. It coordinates communication between systems and serves to organize their communication by offering three different modes: simplex , half duplex , and full duplex . To sum …

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The Presentation Layer

The Presentation layer gets its name from its purpose: it presents data to the Application layer and is responsible for data translation and code formatting. A successful data-transfer technique is to adapt the data into a standard format before transmission. Computers are configured to receive this generically formatted data and then convert it back into …

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The Application Layer

The Application layer of the OSI model marks the spot where users actually communicate or interact with the computer. Technically, users communicate with the network stack through application processes, interfaces, or APIs that connect the application in use to the operating system of the computer. The Application layer chooses and determines the availability of communicating …

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The OSI Reference Model

One of the greatest functions of the OSI specifications is to assist in data transfer between disparate hosts regardless if they’re Unix, Windows, or Mac based. But keep in mind that the OSI model isn’t a physical model; it’s a conceptual and comprehensive yet fluid set of guidelines, which application developers utilize to create and …

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