Data Communications and Networking Solution Manual 2024 with Complete Solution.
CHAPTER 1
Introduction
Solutions to Review Questions and
... [Show More] Exercises
Review Questions
1. The five components of a data communication system are the sender, receiver,
transmission medium, message, and protocol.
2. The advantages of distributed processing are security, access to distributed databases, collaborative processing, and faster problem solving.
3. The three criteria are performance, reliability, and security.
4. Advantages of a multipoint over a point-to-point configuration (type of connection) include ease of installation and low cost.
5. Line configurations (or types of connections) are point-to-point and multipoint.
6. We can divide line configuration in two broad categories:
a. Point-to-point: mesh, star, and ring.
b. Multipoint: bus
7. 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.
8. We give an advantage for each of four network topologies:
a. Mesh: secure
b. Bus: easy installation
c. Star: robust
d. Ring: easy fault isolation
9. The number of cables for each type of network is:
a. Mesh: n (n – 1) / 2
b. Star: n
c. Ring: n – 1
d. Bus: one backbone and n drop lines
10. The general factors are size, distances (covered by the network), structure, and
ownership.
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11. An internet is an interconnection of networks. The Internet is the name of a specific worldwide network
12. A protocol defines what is communicated, in what way and when. This provides
accurate and timely transfer of information between different devices on a network.
13. 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.
Exercises
14. Unicode uses 32 bits to represent a symbol or a character. We can define 2
32 different symbols or characters.
15. With 16 bits, we can represent up to 2
16 different colors.
16.
a. Cable links: n (n – 1) / 2 = (6 × 5) / 2 = 15
b. Number of ports: (n – 1) = 5 ports needed per device
17.
a. Mesh topology: If one connection fails, the other connections will still be working.
b. 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.
c. Bus Topology: All transmission stops if the failure is in the bus. If the drop-line
fails, only the corresponding device cannot operate.
d. Ring Topology: The failed connection may disable the whole network unless it
is a dual ring or there is a by-pass mechanism.
18. This is a LAN. The Ethernet hub creates a LAN as we will see in Chapter 13.
19. 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.
20. In a bus topology, no station is in the path of the signal. Unplugging a station has
no effect on the operation of the rest of the network.
21. See Figure 1.1
22. See Figure 1.2.
23.
a. 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.
b. We normally do not expect a file to be copied immediately. It is not very sensitive to delay.
c. Surfing the Internet is the an application very sensitive to delay. We except to
get access to the site we are searching.
24. In this case, the communication is only between a caller and the callee. A dedicated line is established between them. The connection is point-to-point.
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25. 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.
Figure 1.1 Solution to Exercise 21
Figure 1.2 Solution to Exercise 22
Station
Station Station
Repeat er
Station
Station Station
Repeat er
Station
Station Station
Repeater
Hub
Station
Station
Station
Station
Repeater
Repeater
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CHAPTER 2
Network Models
Solutions to Review Questions and Exercises
Review Questions
1. The Internet model, as discussed in this chapter, include physical, data link, network, transport, and application layers.
2. The network support layers are the physical, data link, and network layers.
3. The application layer supports the user.
4. The transport layer is responsible for process-to-process delivery of the entire
message, whereas the network layer oversees host-to-host delivery of individual
packets.
5. Peer-to-peer processes are processes on two or more devices communicating at a
same layer
6. Each layer calls upon the services of the layer just below it using interfaces
between each pair of adjacent layers.
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.
8. The physical layer is responsible for transmitting a bit stream over a physical
medium. It is concerned with
a. physical characteristics of the media
b. representation of bits
c. type of encoding
d. synchronization of bits
e. transmission rate and mode
f. the way devices are connected with each other and to the links
9. The data link layer is responsible for
a. framing data bits
b. providing the physical addresses of the sender/receiver
c. data rate control
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d. detection and correction of damaged and lost frames
10. The network layer is concerned with delivery of a packet across multiple networks; therefore its responsibilities include
a. providing host-to-host addressing
b. routing
11. The transport layer oversees the process-to-process delivery of the entire message.
It is responsible for
a. dividing the message into manageable segments
b. reassembling it at the destination
c. flow and error control
12. The physical address is the local address of a node; it is used by the data link layer
to deliver data from one node to another within the same network. The logical
address defines the sender and receiver at the network layer and is used to deliver
messages across multiple networks. The port address (service-point) identifies the
application process on the station.
13. The application layer services include file transfer, remote access, shared database management, and mail services.
14. The application, presentation, and session layers of the OSI model are represented
by the application layer in the Internet model. The lowest four layers of OSI correspond to the Internet model layers.
Exercises
15. The International Standards Organization, or the International Organization of
Standards, (ISO) is a multinational body dedicated to worldwide agreement on
international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model.
16.
a. Route determination: network layer
b. Flow control: data link and transport layers
c. Interface to transmission media: physical layer
d. Access for the end user: application layer
17.
a. Reliable process-to-process delivery: transport layer
b. Route selection: network layer
c. Defining frames: data link layer
d. Providing user services: application layer
e. Transmission of bits across the medium: physical layer
18.
a. Communication with user’s application program: application layer
b. Error correction and retransmission: data link and transport layers
c. Mechanical, electrical, and functional interface: physical layer
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d. Responsibility for carrying frames between adjacent nodes: data link layer
19.
a. 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
20. See Figure 2.1.
21. See Figure 2.2.
22. If the corrupted destination address does not match any station address in the network, the packet is lost. If the corrupted destination address matches one of the stations, the frame is delivered to the wrong station. In this case, however, the error
detection mechanism, available in most data link protocols, will find the error and
discard the frame. In both cases, the source will somehow be informed using one
of the data link control mechanisms discussed in Chapter 11. [Show Less]