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Questions Q To make the communication bidirectional, each layer needs to be able to pro- vide two opposite tasks, one in each direction. At the application layer, the unit of data is a message.
Review Questions1. The five components of a data communication system are the sender, receiver, transmission medium, message, and protocol.
The three criteria are performance, reliability, and security. Line configurations or types of connections are point-to-point and multipoint. In half-duplex transmission, only one entity can send at a time; in a full-duplex transmission, both entities can send at the same time. The number of cables for each type of network is: a.
Star: n c. Ring: n 1 d. Bus: one backbone and n drop lines An internet is an interconnection of networks. The Internet is the name of a specific worldwide network Standards are needed to create and maintain an open and competitive market for manufacturers, to coordinate protocol rules, and thus guarantee compatibility of data communication technologies. With 16 bits, we can represent up to different colors. Mesh topology: If one connection fails, the other connections will still be working.
Star topology: The other devices will still be able to send data through the hub; there will be no access to the device which has the failed connection to the hub. Bus Topology: All transmission stops if the failure is in the bus. If the drop-line fails, only the corresponding device cannot operate. Ring Topology: The failed connection may disable the whole network unless it is a dual ring or there is a by-pass mechanism. Theoretically, in a ring topology, unplugging one station, interrupts the ring.
However, most ring networks use a mechanism that bypasses the station; the ring can continue its operation. See Figure 1. E-mail is not an interactive application. Even if it is delivered immediately, it may stay in the mail-box of the receiver for a while. It is not sensitive to delay.
We normally do not expect a file to be copied immediately. It is not very sensitive to delay. Surfing the Internet is the an application very sensitive to delay. We except to get access to the site we are searching. The telephone network was originally designed for voice communication; the Internet was originally designed for data communication.
The two networks are similar in the fact that both are made of interconnections of small networks. The telephone network, as we will see in future chapters, is mostly a circuit-switched network; the Internet is mostly a packet-switched network. The Internet model, as discussed in this chapter, include physical, data link, network, transport, and application layers.
The application layer supports the user. Peer-to-peer processes are processes on two or more devices communicating at a same layer 7.
Headers and trailers are control data added at the beginning and the end of each data unit at each layer of the sender and removed at the corresponding layers of the receiver. They provide source and destination addresses, synchronization points, information for error detection, etc. The data link layer is responsible for a. The transport layer oversees the process-to-process delivery of the entire message.
It is responsible for a. The application layer services include file transfer, remote access, shared database management, and mail services. The International Standards Organization, or the International Organization of Standards, ISO is a multinational body dedicated to worldwide agreement on international standards. Format and code conversion services: presentation layer b. Establishing, managing, and terminating sessions: session layer c.
Ensuring reliable transmission of data: data link and transport layers d. Log-in and log-out procedures: session layer e. Providing independence from different data representation: presentation layer See Figure 2. Figure 2. Reliable process-to-process delivery: transport layer Route selection: network layer Defining frames: data link layer Providing user services: application layer Transmission of bits across the medium: physical layer.
Before using the destination address in an intermediate or the destination node, the packet goes through error checking that may help the node find the corruption with a high probability and discard the packet. Normally the upper layer protocol will inform the source to resend the packet.
The errors between the nodes can be detected by the data link layer control, but the error at the node between input port and output port of the node cannot be detected by the data link layer. Frequency and period are the inverse of each other. Using Fourier analysis. Fourier series gives the frequency domain of a periodic signal; Fourier analysis gives the frequency domain of a nonperiodic signal.
Baseband transmission means sending a digital or an analog signal without modulation using a low-pass channel. Broadband transmission means modulating a digital or an analog signal using a band-pass channel.
The Nyquist theorem defines the maximum bit rate of a noiseless channel. Optical signals have very high frequencies. The frequency domain of a voice signal is normally continuous because voice is a nonperiodic signal.
This is baseband transmission because no modulation is involved. This is broadband transmission because it involves modulation.
See Figure 3. Each signal is a simple signal in this case. The bandwidth of a simple signal is zero. So the bandwidth of both signals are the same. The signal makes 8 cycles in 4 ms. The signal is periodic, so the frequency domain is made of discrete frequencies.
Figure 3. However, power is proportional to the square of voltage. This means we have. When the SNR is doubled, the data rate increases slightly. The three different techniques described in this chapter are line coding, block coding, and scrambling. The data rate defines the number of data elements bits sent in 1s. The unit is bits per second bps.
The signal rate is the number of signal elements sent in 1s. The unit is the baud. When the voltage level in a digital signal is constant for a while, the spectrum creates very low frequencies, called DC components, that present problems for a system that cannot pass low frequencies.
In this chapter, we introduced unipolar, polar, bipolar, multilevel, and multitransition coding. Scrambling, as discussed in this chapter, is a technique that substitutes long zerolevel pulses with a combination of other levels without increasing the number of bits. In parallel transmission we send data several bits at a time.
In serial transmission we send data one bit at a t. Log in Get Started. See Full Reader. Download for free Report this document. Embed Size px x x x x
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Embed Size px x x x x The five components of a data communication system are the sender, receiver,. The advantages of distributed processing are security, access to distributed data-.
With detailed accounts on the data transmission protocols and networking, the book is a useful for various the engineering courses in communication, computer science, and IT. Further, the book also finds usage as a preparatory material for the various other technology related courses too. This book starts with a detailed account on network models, thus providing the user with an ideal introduction on data transmission. The protocols and standards, as well as the physical structures of the networks are also discussed extensively here. A number of diagrams and tabular representations are also included in the book, thus making it more useful for the reader.
Embed Size px x x x x The five components of a data communication system are the sender, receiver,. The advantages of distributed processing are security, access to distributed data-. The three criteria are performance, reliability, and security. Advantages of a multipoint over a point-to-point configuration type of connec-. Line configurations or types of connections are point-to-point and multipoint. We can divide line configuration in two broad categories:.
of each section. o Complete Solutions Manual. Password-protected solutions to all end-of-chapter problems are provided. a Pageout. A free tool that helps you.
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