Unit# 4: Data Communication and Networking

Learning Objectives In this unit you will be learn about: Introduction to DC and Network Transmission modes Types of media Digital and Analog Transmission Asynchronous and Synchronous transmission Network types, Network devices, IP address

Introduction Data communication is the flow of electronic data among two nodes (computers and other devices) through communication media. Data communication refers to the exchange of data between a source and a receiver. Data communication is a process of transferring data electronically from one place to another. Data can be transferred by using different medium.

Introduction Basic Components of Data Communications: Message Sender Receiver Medium/ communication channel Encoder and decoder

Introduction Message The message is the data or information to be communicated. It may consist of text, number, pictures, sound, video or any a combination of these. Sender Sender is a device that sends message. It is also called source or transmitter. Normally, computer is use as sender in information communication systems. Receiver Receiver is a device that receives message. The receiver can be computer, printer or another computer related device. The receiver must be capable of accepting the message.

Introduction Medium Medium is the physical path that connects sender and receiver. It is used to transmit data. The medium can be a copper wire, a fiber optic cable, microwaves etc. it is also called communication channel. Encoder and decoder The encoder is a device that converts digital signals in a form that can pass through a transmission medium. The decoder is a device that converts the encoded signals into digital form.

Data Transmission Modes Three modes of data communication: Simplex Half-duplex Full-duplex

Data Transmission Modes Simplex: Flow of data only in one direction, from the source to the destination. This type of transmission is used when data do not need to flow in both directions. Examples of simplex Mode: loudspeaker, television broadcasting, television and remote, keyboard and monitor

Data Transmission Modes Half-duplex: In half-duplex the data flows in both directions but one at the same time. When the sender is sending the data then at that time we can’t send the sender our message.

Data Transmission Modes Full-duplex: In full-duplex the data flows in both directions at the same time. Each node can thus transmit and receive the data simultaneously. Telephones are common examples of full-duplex devices

Data Transmission Modes

Types of Data Transmission Media Data Transmission Media is the pathway used to carry a communication signal from one system to another. There are two types of transmission media: Guided Media: Use a physical path for communication Un-guided-Media: Does not require any physical path for communication

Types of Data Transmission Media

Data Transmission Media Guided Media: Guided media are more commonly known as wired media, or those media in which electrical or optical signals are transmitted through a cables or wires. Types of Guided Media: Twisted Pair Coaxial Cable Optical Fiber

Data Transmission Media Twisted Pair Wire: Twisted Pair is a couple of copper wires, twisted together and enfolded with a plastic coating. Each pair consists of two wires used for the positive data signal and negative data signal.

Data Transmission Media Coaxial Cable: A Coaxial cable is a cable used in the transmission of video, communications, and audio. This cable has high bandwidths and greater transmission capacity. Most users relate to a coaxial or coax cable as a cable used to connect their TVs to a cable TV service.

Data Transmission Media Optical Fibers: A fiber optic cable contains optical fibers (usually glass) coated in plastic that are used to send data by pulses of light. The coating helps protect the fibers from heat, cold, electromagnetic interference from other types of wiring, as well as some protection from ultraviolet rays from the sun. Fiber optics allow for a much faster data transmission than standard copper wires, due to the fact that they have a much higher bandwidth.

Data Transmission Media

Data Transmission Media Un-Guided Media: Unguided media doesn't use any physical path between the two devices communicating. It simply carries electromagnetic waves without using any physical medium. Unguided media transport electromagnetic waves without using a physical conductor. This type of communication is often referred to as wireless communication. Unguided media included: Microwave Systems Communication Satellite.

Data Transmission Media Microwave: Microwaves are radio waves that are used to provide high-speed transmission. Both voice and data can be transmitted through microwave. Data is transmitted through the air form one microwave station to other similar to radio signals. Communication Satellite: Communication satellite is a space station. It receives microwave signals from earth station. It amplifies the signal and re-transmits them back to earth. Communication satellite is established in space about 22,300 miles above the earth. The data transfer speed of communication satellite is very high.

Data Transmission Media Radio waves are used for multicast communications, such as radio and television, and paging systems. Microwaves are used for unicast communication such as cellular telephones, satellite networks, and wireless LANs. Infrared signals can be used for short-range communication in a closed area using line-of-sight propagation.

Digital and Analog Transmission Analog signal: Transmitted power varies over a continuous range. Example: sound, light, and radio waves Analog is a continuous waveform, with examples such as music and video Digital signal: Sequence of voltage pulses represented in binary form Computer generated data signal is digital, whereas telephone lines carry analog signals

Analog signal A sine wave

Analog signal Amplitude

Analog signal Period and frequency Frequency is the rate of change with respect to time. Change in a short span of time means high frequency. Change over a long span of time means low frequency.

Analog Signals Components Amplitude Frequency Phase

Analog Signals Components Amplitude: The amplitude of a signal is the height of the wave above or below a given reference point. Frequency: The frequency is the number of times a signal makes a complete cycle within a given time frame. Phase: The phase of a signal is the position of the waveform relative to a given moment of time or relative to time zero.

A sine wave example (Analog signal)

Digital Signals In Digital signal data can be represented by digits that is 1 and Zero. For example, a 1 can be encoded as a positive voltage and a 0 as zero voltage.

Bit Interval The Bit Interval is the time required to send one single bit. The Bit Rate is the number of bit intervals per second. So, the Bit Rate is the number of bits send in 1 second and is usually expressed in Bits Per Second i.e. bps

Synchronous transmission Synchronous transmission is transmission of signals in a fixed interval based on a predefined clocking signal and is meant for constant and reliable transmission of time-sensitive data such as VoIP and audio/video streaming.

Synchronous transmission This method of transmission is used when large amounts of data need to be transferred quickly since data is transferred in large blocks instead of individual characters

Asynchronous transmission Asynchronous transmission is the transmission of data in which each character is a self-contained unit with its own start and stop bits and an uneven interval between them. Asynchronous transmission uses start and stop bits to signify the beginning and ending bits. The additional one at the start and end of a transmission alerts the receiver to the occurrence of the first character and last character. 

Network types LAN - Local Area Network. MAN - Metropolitan Area Network. WAN - Wide Area Network.

LAN - Local Area Network A local area network (LAN) is a computer network within a small geographical area such as a home, school, computer laboratory, office building or group of buildings. Transfer data with very high speed. They exist in a small geographical area. The LAN technology is less expensive

LAN - Local Area Network

MAN - Metropolitan Area Network A metropolitan area network (MAN) is similar to a local area network (LAN) but spans an entire city or campus. MANs are formed by connecting multiple LANs. Thus, MANs are larger than LANs but smaller than wide area networks (WAN).  MANs are extremely efficient and provide fast communication via high-speed carriers, such as fiber optic cables.

MAN - Metropolitan Area Network

WAN - Wide Area Network A wide area network (WAN) is a network that exists over a large-scale geographical area. A WAN connects different smaller networks, including local area networks (LANs) and metro area networks (MANs). WANs are similar to a banking system, where hundreds of branches in different cities are connected with each other in order to share their official data. A WAN works in a similar fashion to a LAN, just on a larger scale. Typically, TCP/IP is the protocol used for a WAN in combination with devices such as routers, switches, firewalls and modems.

WAN - Wide Area Network

Network devices Network Devices are used for: Controlling traffic: Large networks need a way to filter and isolate data traffic. Connectivity: These devices can connect different types of networks using different types of network protocols. Hierarchical addressing: Segmenting the network with connectivity devices provides an actual (physical) example of delivering actual data to the right destination through the IP address's network ID and host ID. Bridge Hub Switch Router

Bridge A network bridge helps to join two separate computer networks together to enable communication between them. Bridge devices are used with local area networks (LANs) for extending their reach to cover larger physical areas. A connectivity device that forwards data based on a physical address. A bridge filters and forwards packets by physical address. Bridges operate at the Network Access Layer in the TCP/IP protocol stack.

Bridge

Hub A hub is the most basic networking device that connects multiple computers or other network devices together. A connectivity device to which network cables are attached to form a network segment. Hubs typically do not filter data, but instead retransmit incoming data packets or frames to all parts.

Hub

Switch A switch is a hardware device that filters and forwards network packets, but often not capable of much more. A switch, simplified, is a smarter version of a hub. On a switch, as with a hub, each computer is connected through a single line. However, the switch is smarter about where it sends data that comes in through one of its ports.

Switch

Router Router is hardware device designed to receive, analyze and move incoming packets to another network. A router connects networks A router acts as a dispatcher as it decides which way to send each information packet A router is located at any gateway (where one network meets another) It may also be used to convert the packets to another network interface, drop them, and perform other actions relating to a network. 

Router Wireless router Brouter: Short for Bridge Router, a brouter is a networking device that serves as both a bridge and a router. Core router A core router is a router in a computer network that routes data within a network, but not between networks. Edge router: For information on an edge router, see our edge device definition page. Wireless router

IP address Short of IP is Internet Protocol address. IP address (Internet Protocol address) is a numerical label. It is basically assigned to each computer which is being participated in a computer-network (that uses the “Internet Protocol” for communication) IP or IP address is a number (172.16.50.16) used to indicate the location of a computer or other device on a network using TCP/IP. TCP/IP (Transmission Control Protocol/Internet Protocol) is a set of rules (protocols) governing communications among all computers on the Internet. 

Assignment What is network topology? How many types of network topologies? Explain with diagram examples

Network topology Connection arrangement of the various links and nodes of a computer network. Structure of a network that defines configuration of cables, computers, and other peripherals. Star Topology Ring Topology Bus Topology Mesh Topology

Star Topology

Ring Topology

Bus Topology

Mesh Topology