Class lecture notes for third Year,sixth semester Computer Networks (Subject Code: EC) is available here in PDF formats for you to. In recent years, the network that is making significant impact in our day-to-day life is the Computer network. By computer network we mean an interconnected set. EC / EC62 / EC Computer Networks Complete Notes-Unit Wise ECE 6th Semester Regulation | BE Electronics and Communication.

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Where is the Menu? How to request Study Material? What is mean by data communication? Data communication is the exchange of data in the form of 1s and 0s between two devices via some form of transmission medium networkks as a wire cable. What are the three criteria necessary for an effective and efficient network? The most important criteria are performance, reliability and security. Security issues include protecting data from unauthorized access and viruses.

EC COMPUTER NETWORKS SYLLABUS | Online Engineering

What are the three fundamental characteristics determine the effectiveness of the data communication system? The effectiveness of the data communication system depends on three fundamental characteristics: The system must deliver data to the correct destination. The system must deliver data accurately. The system must deliver data in a timely manner. What are the advantages of distributed processing? Why are protocols needed? In networks, communication occurs between the entities in different systems.

Two entities cannot just send bit streams to each other and expect to be understood. For communication, the entities must agree on a protocol. A protocol is a set of rules that govern data communication 6. Why are standards needed? Co-ordination across the nodes of a network is necessary for an efficient communication. If there are no standards, difficulties arise. A standard provides a model or basis for development to which everyone has agreed.

What is the difference between a passive and an active hub? An active hub contains a repeater that regenerates the received bit patterns before sending them out. A passive hub provides a simple physical connection between the attached devices.

Distinguish between peer-to-peer relationship and a primary-secondary relationship. P e e r -t o-peer relationship: All the devices share the link equally.

P r i m ary-secondary relationship: One device controls traffic and the others must transmit through it. Raghavendra Reddy Malapati Page 2 9.

Group the OSI layers by function. The seven layers of the OSI model belonging to three notse. Physical, data link and network layers are the network support layers; they deal with the physical aspects of moving data from one device to another.

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Session, presentation and application layers are the user support layers; they allow interoperability among unrelated software systems. The transport layer ensures end-to-end reliable data transmission. What are header and trailers and how do they get added and removed? Each layer in the sending machine adds its own information to the message it receives from the layer just above it and passes the whole package to the layer just below it.

This information is added in the form of headers or trailers. Headers are added to the message at the layers 6,5,4,3, and 2. A computdr is added at layer2. At the receiving machine, the headers or trailers attached to the data unit at the corresponding sending layers are removed, and actions appropriate to that layer are taken. The transport layer creates a communication between the source and destination. What are the three events involved in a connection? Creating a connection involves three steps: In the NRZ-L sequence, positive and negative voltages have specific meanings: Instead, the receiver looks for changes from one level to another as its basis for recognition of 1s.

What notess the functions of a DTE? What are the functions of a DCE? Data terminal equipment is a device that is an information source or an information sink. It is connected to a network through a DCE. Data circuit-terminating equipment is a device used as an interface between a DTE and a network. What does the electrical specification of EIA describe?

The data must be transmitted using NRZ-L encoding. Discuss the mode for propagating light along optical channels There are two modes for propagating light along optical channels, multimode and single mode.

Multiple beams compjter a light source move through the core in different paths. Fiber with extremely small diameter that limits beams to a few angles, resulting in an almost netwkrks beam. The phenomenon related to the bending of light when it passes from one medium to another.

Raghavendra Reddy Malapati Page 3 What are the disadvantages of optical fiber as a transmission medium? What are the criteria used to evaluate transmission medium? Explain cross talk and what is needed to reduce it? Effect of one wire on another is called as cross talk.

EC2352 – Computer Networks Important Questions

One neworks will be the sending antenna and the other wire will be the receiving antenna. We can use the shielded twisted pair cable or coaxial cable for transmission, which contains metal foil to reduce cross talk. What are the responsibilities of data link layer? Specific responsibilities of data link layer include the following. Mention the types of errorsE There are 2 types of errors a Single-bit error. Define the following terms. Means that 2 or more bits in the data unit have changed from 1 to 0 or from 0 to 1.

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It is the error detecting mechanism, which means a shorter group of bits or compuher bits may be appended at the destination of each unit. List out the available detection methods. There are 4 types of redundancy checks are used in data communication. Write short notes on VRC. The most common and least expensive mechanism for error detection is the vertical redundancy check VRC often called a parity check. Write short notes on LRC. In longitudinal redundancy check LRCa block of bits is divided into rows and a redundant row of bits is added to the whole block.

Write short notes on CRC.

The third and most powerful of computeg redundancy checking techniques is the cyclic redundancy checks CRC CRC is based on binary division. Here a sequence of redundant bits, called the CRC remainder is appended to the end of data unit. Write short notes on CRC generator. A CRC generator uses a modulo-2 division.

EC2352 Computer Networks MJ2014 Question Paper

Write short notes on CRC checker. A CRC checker functions exactly like a generator. After receiving the data appended with the CRC it does the same modulo-2 division.

Otherwise, the received stream of bits is discarded and the dates are resent. What are the steps followed in checksum generator? The sender follows these steps a The units are divided into k sections each of n bits. List out the steps followed is checksum checker side. The receiver must follow these steps a The unit is divided into k section each coputer n bits. Write short notes on error correction. It is compkter mechanism to correct the errors and it can be handled in 2 ways.

What is the purpose of hamming code? A hamming code can be designed to correct burst errors of certain lengths. So the simple strategy vomputer by the hamming code to correct single bit errors must be redesigned to be applicable for multiple bit correction. Flow control refers to a set of procedures used to restrict the amount of data. The sender can send before waiting for acknowledgment. What is a buffer?

Each receiving device has a block of memory called a buffer, reserved for storing incoming data until they are processed.