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Chapter 11. Diffentiate Following Connection oriented vs Connectionless LAN Vs PAN Vs WAN OSI Reference Model Vs TCP Reference Model Analog Signal Vs Digital SignalFunctions of Application layer:File transfer, access, and management (FTAM),Mail services, Directory servicesTranslation,Encryption,...

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Chapter 1 1. Diffentiate Following  Connection oriented vs Connectionless

 LAN Vs PAN Vs WAN

 OSI Reference Model Vs TCP Reference Model

 Analog Signal Vs Digital Signal

2. Explain OSI reference model with brief functionality of each layer. OSI stands for Open System Interconnection is a reference model that describes how information from a software application in one computer moves through a physical medium to the software application in another computer. OSI consists of seven layers, and each layer performs a particular network function.

Functions of Application layer: File transfer, access, and management (FTAM),Mail services,Directory services

Translation,Encryption,Compression

Dialog control,Synchronization

Functions of Transport Layer: Service-point addressing,Service-point addressing,Connection control,Flow control,Error control

Functions of Network Layer: Internetworking,Addressing,Routing,Packetizing

Functions of Data-link Layer: Framing,Physical Addressing,Flow Control,Error Control,Access Control

Line Configuration,Line Configuration,Topology,Signals

3. Define Computer Network? What are different types of networks? Or Explain Local Area Network.(4 mark) A computer network is a set of devices connected through links. A node can be computer, printer, or any other device capable of sending or receiving the data. The links connecting the nodes are known as communication channels. Computer Network uses distributed processing in which task is divided among several computers. Instead, a single computer handles an entire task, each separate computer handles a subset.

LAN(L ocal Area Network) o Local Area Network is a group of computers connected to each other in a small area such as building, office. o LAN is used for connecting two or more personal computers through a communication medium such as twisted pair, coaxial cable, etc. o It is less costly as it is built with inexpensive hardware such as hubs, network adapters, and ethernet cables. o The data is transferred at an extremely faster rate in Local Area Network. o Local Area Network provides higher security.

PAN(Personal Area Network) o Personal Area Network is a network arranged within an individual person, typically within a range of 10 meters. o Personal Area Network is used for connecting the computer devices of personal use is known as Personal Area Network. o Thomas Zimmerman was the first research scientist to bring the idea of the Personal Area Network. o Personal Area Network covers an area of 30 feet. o Personal computer devices that are used to develop the personal area network are the laptop, mobile phones, media player and play stations.

MAN(Metropolitan Area Network) o A metropolitan area network is a network that covers a larger geographic area by interconnecting a different LAN to form a larger network. o Government agencies use MAN to connect to the citizens and private industries. o In MAN, various LANs are connected to each other through a telephone exchange line. o The most widely used protocols in MAN are RS-232, Frame Relay, ATM, ISDN, OC-3, ADSL, etc. o It has a higher range than Local Area Network(LAN).

WAN(Wide Area Network) o A Wide Area Network is a network that extends over a large geographical area such as states or countries. o A Wide Area Network is quite bigger network than the LAN. o A Wide Area Network is not limited to a single location, but it spans over a large geographical area through a telephone line, fibre optic cable or satellite links. o The internet is one of the biggest WAN in the world. o A Wide Area Network is widely used in the field of Business, government, and education.

4. What is TCP reference Model? Explain the functions and protocols and services of each layer?

5. Explain ARPANET(4 Mark) It started Paul Baran in 1960s funded by Advanced Research Projects Agency (ARPA), an organization of the united States Defense Department and, therefore, named as Advanced Research Projects Agency Network (ARPANET) predecessor of the modern Internet. It was world's first fully operational packet switching computer network and the world's first successful computer network to implement the TCP/IP reference model that was used earlier by ARPANET, before being used in the Internet. The ARPANET is the first network that planed the seed of interent. ARPANET was built to accommodate research equipment on packet switching technology and to allow resource sharing for the Department of Defense's contractors. The network interconnected research centers, some military bases and government locations. It soon became popular with researchers for collaboration through electronic mail and other services. • It is basically a WAN. It was developed by the ARPA (Advanced Research Project Agency) in 1968 which is the research arm of 000. • ARPANET was designed to service even a nuclear attack. • Before ARPANET, the networks were basically the telephone networks which operated on the circuit switching principle. • But this network was too vulnerable, because the loss of even one line or switch would terminate all the conversations. • ARPANET used the concept of packet switching network consisting of subnet and host

computers. • The subnet was a datagram subnet and each subnet consists of minicomputers called IMPs (Interface Message Processors). • Each node of the network used to have an IMP and a host connected by a short wire. • The host could send messages of upto 8063 bits to its IMP which would break them into packets and forward them independently toward the destination. • The subnet was the first electronic store-and-forward type packet switched network. So each packet was stored before it was forwarded.

• The software for ARPANET was split into two parts namely subnet and host. • In 1974 the TCP/IP model and protocol were invented specifically to handle communication over internetwork because more and more networks were getting connected to ARPANET. • The TCP/IP made the connection of LANs to ARPANET easy.

Chapter 2 6. Diffentiate Following  Compare full-duplex and half-duplex communication

 multimode and single mode fiber

 Compare fiber optics and copper wire

 How OFDM is better compare to FDM.

 FDM Vs TDM

 Twisted Pair Wire Vs Coaxial Cable

 Guided media Vs Unguided media

 Fiber Optics and Satellite Communication.

7. Explain coaxial cable with diagram. Coaxial cable is very commonly used transmission media, for example, TV wire is usually a coaxial cable. The name of the cable is coaxial as it contains two conductors parallel to each other. It has a higher frequency as compared to Twisted pair cable. The inner conductor of the coaxial cable is made up of copper, and the outer conductor is made up of copper mesh. The middle core is made up of non-conductive cover that separates the inner conductor from the outer conductor. The middle core is responsible for the data transferring whereas the copper mesh prevents from the EMI(Electromagnetic interference).

Coaxial cable is of two types: 1. Baseband transmission: It is defined as the process of transmitting a single signal at high speed. 2. Broadband transmission: It is defined as the process of transmitting multiple signals simultaneously. Advantages Of Coaxial cable: o The data can be transmitted at high speed. o It has better shielding as compared to twisted pair cable. o It provides higher bandwidth. Disadvantages Of Coaxial cable: o It is more expensive as compared to twisted pair cable. o If any fault occurs in the cable causes the failure in the entire network.

8. What is electromagnetic spectrum? (4 mark) The electromagnetic spectrum is the entire range of electromagnetic radiation according to the wavelength or frequencies. It has a range of frequencies from 1Hz to Hz. The waves in order of increasing frequencies are radio waves, microwaves, infrared rays, visible light, UV rays, X-rays and gamma rays.Among these range, the frequencies between Hz to Hz are used for communication.

The following diagram shows the electromagnetic spectrum. The first figure gives the full range of frequency spectrum while the second figure elaborates that part of the spectrum which can be used for data communication –

9. What is Modulation? List modulation techniques and explain any one in detail. Modulation is nothing but, a carrier signal that varies in accordance with the message signal. Modulation technique is used to change the signal characteristics. Basically, the modulation is of following two types:

Analog Modulation In analog modulation, analog signal (sinusoidal signal) is used as a carrier signal that modulates the message signal or data signal. The general function Sinusoidal wave’s is shown in the figure below, in which, three parameters can be altered to get modulation – they are amplitude, frequency and phase; so, the types of analog modulation are:

Digital Modulation For a better quality and efficient communication, digital modulation technique is employed. The main advantages of the digital modulation over analog modulation include available bandwidth , high noise immunity and permissible power. In digital modulation, a message signal is converted from analog to digital message, and then modulated by using a carrier wave.

10.Explain Guided media and Unguided media.

Twi s t edpai r : Twisted pair is a physical media made up of a pair of cables twisted with each other. A twisted pair cable is cheap as compared to other transmission media. Installation of the twisted pair cable is easy, and it is a lightweight cable. The frequency range for twisted pair cable is from 0 to 3.5KHz.

Advantages Of Radio transmission: o

Radio transmission is mainly used for wide area networks and mobile cellular phones.

o

Radio waves cover a large area, and they can penetrate the walls.

o

Radio transmission provides a higher transmission rate

11.Explain Passband transmission ?

12. Explain in brief duties of Physical layer?(4 Mark) o The main functionality of the physical layer is to transmit the individual bits from one node to another node. o It is the lowest layer of the OSI model. o It establishes, maintains and deactivates the physical connection. o It specifies the mechanical, electrical and procedural network interface specifications. Functions of a Physical layer: o Line Configuration: It defines the way how two or more devices can be connected physically. o Data Transmission: It defines the transmission mode whether it is simplex, half-duplex or full-duplex mode between the two devices on the network. o Topology: It defines the way how network devices are arranged. o Signals: It determines the type of the signal used for transmitting the information. o Bit synchronization: The physical layer provides the synchronization of the bits by providing a clock. This clock controls both sender and receiver thus providing synchronization at bit level. o Bit rate control: The Physical layer also defines the transmission rate i.e. the number of bits sent per second. o Physical topologies: Physical layer specifies the way in which the different, devices/nodes are arranged in a network i.e. bus, star or mesh topolgy. o Transmission mode: Physical layer also defines the way in which the data flows between the two connected devices. The various transmission modes possible are: Simplex, halfduplex and full-duplex.

Chapter 3 13.What is mean by Elementary Data Link Protocols? Explain Utopian Simplex Protocol in detail

Framing is the process of dividing bit - streams from physical layer into data frames whose size ranges from a few hundred to a few thousand bytes. Error control mechanisms deals with transmission errors and retransmission of corrupted and lost frames. Flow control regulates speed of delivery and so that a fast sender does not drown a slow receiver.

At first we will discuss about the elementary Protocols. Elementary DLL Protocols are further divided into three protocols. They are :   

An Unrestricted(Utopian) simplex protocol A simplex stop and wait protocol A simplex protocol for a noisy channel

 I. AN UNRESTRICTED(Utopian) SIMPLEX PROTOCOL: The Simplex protocol is data link layer protocol for transmission of frames over computer network. It is hypothetical protocol designed for unidirectional data transmission over an ideal channel, i.e. a channel through which transmission can never go wrong. It is assumed that both the sender and the receiver are always ready for data processing and both of them have infinite buffer. The sender simply sends all its data available onto the channel as soon as they are available its buffer. The receiver is assumed to process all incoming data instantly. It is does not handle flow control or error control. Since this protocol is totally unrealistic, it is often called Utopian Simplex protocol. The significance of this protocol lies in the fact that it shows the basic structure on which the usable protocols are built upon.

Design  Sender Site: The data link layer in the sender site waits for the network layer to send a data packet. On receiving the packet, it immediately processes it and sends it to the physical layer for transmission.

 Receiver Site: The data link layer in the receiver site waits for a frame to be available. When it is available, it immediately processes it and sends it to the network layer.

 II. A SIMPLEX STOP AND WAIT PROTOCOL: Stop-and-wait o

In the Stop-and-wait method, the sender waits for an acknowledgement after every frame it sends.

o

When acknowledgement is received, then only next frame is sent. The process of alternately sending and waiting of a frame continues until the sender transmits the EOT (End of transmission) frame.

Advantage of Stop-and-wait The Stop-and-wait method is simple as each frame is checked and acknowledged before the next frame is sent. Disadvantage of Stop-and-wait Stop-and-wait technique is inefficient to use as each frame must travel across all the way to the receiver, and an acknowledgement travels all the way before the next frame is sent. Each frame sent and received uses the entire time needed to traverse the link.

 III. A SIMPLEX PROTOCOL FOR A NOISY CHANNEL: Simplex Stop – and – Wait protocol for noisy channel is data link layer protocol for data communications with error control and flow control mechanisms. It is popularly known as Stop – and –Wait Automatic Repeat Request (Stop – and –Wait ARQ) protocol. It adds error control facilities to Stop – and – Wait protocol Stop-and-wait ARQ is a technique used to retransmit the data in case of damaged or lost frames. This technique works on the principle that the sender will not transmit the next frame until it receives the acknowledgement of the last transmitted frame.

Design 

Sender Site: At the sender site, a field is added to the frame to hold a sequence number. If data is available, the data link layer makes a frame with the certain sequence number and sends it. The sender then waits for arrival of acknowledgment for a certain amount of time. If it receives a positive

acknowledgment for the frame with that sequence number within the stipulated time, it sends the frame with next sequence number. Otherwise, it resends the same frame. 

Receiver Site: The receiver also keeps a sequence number of the frames expected for arrival. When a frame arrives, the receiver processes it and checks whether it is valid or not. If it is valid and its sequence number matches the sequence number of the expected frame, it extracts the data and delivers it to the network layer. It then sends an acknowledgement for that frame back to the sender along with its sequence number.

14. Give comparison between a transport layer and data link layer.(4 mark) transport layer data link layer The Transport layer is a Layer 4 The data link layer is a Layer 2 The Transport layer is a Layer 4 ensures This layer is responsible for the error-free that messages are transmitted in the order in transfer of data frames. which they are sent and there is no duplication of data. This layer divide the data into segments. Encapsulation of packets into frames is done here. These frames are then transferred to the physical layer. Protocols used : TCP and UDP The Data Link Layer protocols are Ethernet, token ring, FDDI and PPP. Functions of Transport Layer Service-point addressing Segmentation and reassembly Connection control Flow control Error control

Functions of the Data-link layer Framing Physical Addressing Flow Control Error Control Access Control

15.What are duties of Data Link Layer? This layer is responsible for the error-free transfer of data frames. It defines the format of the data on the network. It provides a reliable and efficient communication between two or more devices. It is mainly responsible for the unique identification of each device that resides on a local network. It contains two sub-layers:

a.

Logical Link Control Layer i. It is responsible for transferring the packets to the Network layer of the receiver that is receiving. ii. It identifies the address of the network layer protocol from the header. iii. It also provides flow control.

b.

Media Access Control Layer i. A Media access control layer is a link between the Logical Link Control layer and the network's physical layer. ii. It is used for transferring the packets over the network.

Functions of the Data-link layer o

Framing: The data link layer translates the physical's raw bit stream into packets known as Frames. The Data link layer adds the header and trailer to the frame. The header which is added to the frame contains the hardware destination and source address.

o

Physical Addressing: The Data link layer adds a header to the frame that contains a destination address. The frame is transmitted to the destination address mentioned in the header.

o

Flow Control: Flow control is the main functionality of the Data-link layer. It is the technique through which the constant data rate is maintained on both the sides so that no data get corrupted. It ensures that the transmitting station such as a server with higher processing speed does not exceed the receiving station, with lower processing speed.

o

Error Control: Error control is achieved by adding a calculated value CRC (Cyclic Redundancy Check) that is placed to the Data link layer's trailer which is added to the message frame before it is sent to the physical layer. If any error seems to occurr, then the receiver sends the acknowledgment for the retransmission of the corrupted frames.

o

Access Control: When two or more devices are connected to the same communication channel, then the data link layer protocols are used to determine which device has control over the link at a given time.

16.Explain Sliding Window protocol with example. What is the relevance of sending window? 

The Sliding Window is a method of flow control in which a sender can transmit the several frames before getting an acknowledgement.



In Sliding Window Control, multiple frames can be sent one after the another due to which capacity of the communication channel can be utilized efficiently.



A single ACK acknowledge multiple frames.



Sliding Window refers to imaginary boxes at both the sender and receiver end.



The window can hold the frames at either end, and it provides the upper limit on the num...