Summary of Previous
In the previous lecture we have learnt, Managing business data MS Access 2007
Purpose and Data OrganizationCreating a Database
Table Form Query Report
Summary of Previous Data Presentation
Purpose and Types of presentations Microsoft Power Point A New presentation Design Templates Animation Slide Master Adding Pictures Working With Text Graphs and Charts
4
Today’s Topics Introduction to Telecommunications
Basic Components of Communications Telecommunications Media Rate of data transfer
Define the basic terminology of computer networks Network Topology Classification of Computer Networks Network Devices Recognize the individual components of the big picture
of computer networks
Today’s Topics Computer Network Layouts
Microcomputer-to-local area networkMicrocomputer-to-InternetLocal area network-to-local area networkPersonal area network-to-workstationLocal area network-to-metropolitan area
networkLocal area network-to-wide area network
Today’s TopicsSensor-to-local area networkSatellite and microwaveCell phonesComputer terminal / microcomputer-to-
mainframe Summary
7
Introduction Everyone is using a computer network today. Mass transit, interstate highways, 24-hour
bankers, grocery stores, cable television, cell phones, businesses and schools, and retail outlets support some form of computer network
What is Telecommunication?
Transmission of different forms of data such as text, audio, video, images, graphics
It occurs between one set of electronic
devices over media to another set of
geographically separated electronic devices.
Basic Components of Communications
Sender: Person or device sending the
message
Receiver: Person or device receiving the
message
Medium: What carries the message from
sender to receiver
Sender
Person
Receiver Person
Channel/Medium
A short distance of air
Message
Voice
Face-to-face Communication
Sender Telephone, Computer,
Video Conferencin
g
Channel/Medium Various
Types of Electronic Media
Message Voice, Data Video, etc.
Receiver Telephone, Computer,
Video Conferencin
g
Telecommunications
Telecommunications Media Communications media - the paths, or physical
channels, in a network over which information travels.
Wired communications media - transmit information over a closed, connected path.
Wireless communications media - transmit information through the air.
Telecommunication – Rate of data transfer Data transmission channels (bps)
narrow bands: 5-30voice bands: 1,000-9,600broad bands: 100,000
16
What is Computer Network? Computer network is an interconnection of
computers and computing equipment using either wires or radio waves over small or large geographic areas
Network Topology – Connecting Computers
The network topology defines the way in which computers, printers, and other devices are connected.
A network topology describes the layout of the wire and devices as well as the paths used by data transmissions.
Bus Topology
Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable.
Ring Topology
A network configuration in which computers are arranged in the form of a ring using twisted-wire, coaxial cable, or fiber optics.
Messages are transmitted in one direction to all devices between the sending node and the receiving node.
Star Topology
A topology in which a central host
computer receives all messages and
then forwards the message to the
appropriate computer on the network.
Mesh TopologyThe mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance.
It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions.
Implementing the mesh topology is expensive and difficult.
Different Types of Network Exists
Local area network Networks that are small in geographic
size spanning a room, floor, building, or campus
Types Metropolitan area network
Networks that serve an area of 1 to 30 miles, approximately the size of a typical city
MAN MAN networks are generally good for
businesses and organizations that have multiple locations around a city. A bank may also take advantage of a MAN.
Types Wide area network
a large network that encompasses parts of states, multiple states, countries, and the world
Types Personal area network
a network of a few meters, between wireless devices such as PDAs, laptops, and similar devices
Types Voice network
a network that transmits only telephone signals (almost extinct)
Data network a network that transmits voice and computer
data (replacing voice networks)
32
Computer Network Popular Terms
Data communications – the transfer of digital or analog data using digital or analog signals
Telecommunications – the study of telephones and the systems that transmit telephone signals (becoming simply data communications)
Popular Terms Network management – the design,
installation, and support of a network, including its hardware and software
Network cloud – a network (local or remote) that contains software, applications, and/or data
34
The Big Picture of Networks Networks are composed of many devices,
including:Workstations (computers, tablets, wireless
phones, etc)ServersNetwork hubs and switches Routers (LAN to WAN and WAN to WAN)Telephone switching gear
Network Devices Workstations
They are personal computers/microcomputers (desktops, laptops, net books, hand held, etc.) where users reside
Servers, They are the computers that store network
software and shared or private user files
Network Devices Switches,
They are the collection points for the wires that interconnect the workstations
Routers, They are the connecting devices between
local area networks and wide area networks
41
Basic Layouts of Communication networks Microcomputer-to-local area network Microcomputer-to-Internet Local area network-to-local area network Personal area network-to-workstation Local area network-to-metropolitan area
network
42
Local area network-to-wide area network Sensor-to-local area network Satellite and microwave Cell phones Computer terminal / microcomputer-to-
mainframe
Basic Layouts of Communication networks
43
Highly common throughout business and academic environments, and now homes
Typically a medium- to high-speed connection
Computer (device) requires a NIC (network interface card)
NIC connects to a hub-like device (switch)
Micro Computer to Local Area Network Layout
46
Microcomputer-to-Internet Layout
Popular with home users and small businesses
For some, a dial-up modem is used to connect user’s microcomputer to an Internet service provider
Technologies such as DSL and cable modems are replacing modems
49
Local Area Network-to-Local Area Network Layout
Found in systems that have two or more LANs and a need for them to intercommunicate
A bridge-like device (such as a switch) is typically used to interconnect LANs
50
Local Area Network-to-Local Area Network Layout (continued)
Hardware that connects
computers to one another on a local network.
51
Personal Area Network-to-Workstation Layout Interconnects wireless devices such as
PDAs, laptops and notebooks, and music playback devices
Used over short distances such as a few meters
54
Local Area Network-to-Metropolitan Area Network Layout Used to interconnect companies (usually
their local area networks) to networks that encompass a city
High-speed networks Typically, this interconnection uses only fiber-
optic links
56
Local Area Network-to-Wide Area Network Layout One of the most common ways to
interconnect a user on a LAN workstation to the Internet (a wide area network)
A router is the typical device that performs LAN to WAN connections
Routers are more complex devices than switches
Data Communications and Computer Networks: A Business User's Approach, Sixth Edition 57
Local Area Network-to-Wide Area Network Layout (continued)
58
Wide Area Network-to-Wide Area Network Layout High-speed routers and switches are used
to connect one wide area network to another
Thousands of wide area networks across Pakistan, many interconnected via these routers and switches
59
Sensor-to-Local Area Network Layout
Not all local area networks deal with microcomputer workstations
Often found in industrial and laboratory environments
Assembly lines and robotic controls depend heavily on sensor-based local area networks
61
Satellite and Microwave Layout Typically long distance wireless connections Many types of applications including long
distance telephone, television, radio, long-haul data transfers, and wireless data services
Typically expensive services but many companies offer competitive services and rates
Newer shorter-distance services such as Wi-Max
63
Cell Phone Layout Expanding market across the world specially
Pakistan. Third generation services available in many
areas and under many types of plans with fourth generation services starting to appear
Latest generation includes higher speed data transfers (100s to 1000s of kilobits per second)
65
Terminal/Microcomputer-to-Mainframe Computer Layout Predominant form in the 1960s and 1970s Still used in many types of businesses for data
entry and data retrieval Few dumb terminals left today, e.g. Telnet
67
One More Layout An Additional Basic layout – telephone-to-
networkTelephone systems are ubiquitous and now
carry more data than voiceVoice over IP – telephone-to-LAN via gateway
or telephone to gateway via DSL/cable