Data Communication & Network

DATA COMMUNICATION
& NETWORKING
MIDTERM LESSON

Data Communication and Computer Network
A system of interconnected computers and computerized peripherals such as printers
is called computer network. This interconnection among computers facilitates
information sharing among them. Computers may connect to each other by either
wired or wireless media.
ClassificationofComputerNetworks
Computer networks are classified based on various factors. They include:
 Geographical span
 Inter-connectivity
 Administration
 Architecture
GeographicalSpan
Geographically a network can be seen in one of the following categories:
 It may be spanned across your table, among Bluetooth enabled devices,
Ranging not more than few meters.
 It may be spanned across a whole building, including intermediate devices to
connect all floors.
 It may be spanned across a whole city.
 It may be spanned across multiple cities or provinces.
 It may be one network covering whole world.
Inter-Connectivity
Components of a network can be connected to each other differently in some fashion.
By connectedness we mean either logically, physically, or both ways.
 Every single device can be connected to every other device on network, making
the network mesh.
 All devices can be connected to a single medium but geographically
disconnected, created bus-like structure.
 Each device is connected to its left and right peers only, creating linear
structure.
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OVERVIEW

 All devices connected together with a single device, creating star-like
structure.
 All devices connected arbitrarily using all previous ways to connect each other,
resulting in a hybrid structure.
Administration
From an administrator’s point of view, a network can be private network which
belongs a single autonomous system and cannot be accessed outside its physical or
logical domain. A network can be public, which is accessed by all.
NetworkArchitecture
Computer networks can be discriminated into various types such as Client-Server,
peer-to-peer or hybrid, depending upon its architecture.
 There can be one or more systems acting as Server. Other being Client,
requests the Server to serve requests. Server takes and processes request on
behalf of Clients.
 Two systems can be connected Point-to-Point, or in back-to-back fashion. They
both reside at the same level and called peers.
 There can be hybrid network which involves network architecture of both the
above types.
NetworkApplications
Computer systems and peripherals are connected to form a network. They provide
numerous advantages:
 Resource sharing such as printers and storage devices
 Exchange of information by means of e-Mails and FTP
 Information sharing by using Web or Internet
 Interaction with other users using dynamic web pages
 IP phones
 Video conferences
 Parallel computing
 Instant messaging
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Generally, networks are distinguished based on their geographical span. A network
can be as small as distance between your mobile phone and its Bluetooth headphone
and as large as the internet itself, covering the whole geographical world.
PersonalAreaNetwork
A Personal Area Network (PAN) is smallest network which is very personal to a user.
This may include Bluetooth enabled devices or infra-red enabled devices. PAN has
connectivity range up to 10 meters. PAN may include wireless computer keyboard
and mouse, Bluetooth enabled headphones, wireless printers, and TV remotes.
For example, Piconet is Bluetooth-enabled Personal Area Network which may contain
up to 8 devices connected together in a master-slave fashion.
LocalAreaNetwork
A computer network spanned inside a building and operated under single
administrative system is generally termed as Local Area Network (LAN). Usually, LAN
covers an organization offices, schools, colleges or universities. Number of systems
connected in LAN may vary from as least as two to as much as 16 million.
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TYPE OF COMPUTER
NEWORKS

LAN provides a useful way of sharing the resources between end users. The resources
such as printers, file servers, scanners, and internet are easily sharable among
computers.
LANs are composed of inexpensive networking and routing equipment. It may
contains local servers serving file storage and other locally shared applications. It
mostly operates on private IP addresses and does not involve heavy routing. LAN
works under its own local domain and controlled centrally.
LAN uses either Ethernet or Token-ring technology. Ethernet is most widely employed
LAN technology and uses Star topology, while Token-ring is rarely seen.
LAN can be wired, wireless, or in both forms at once.
MetropolitanAreaNetwork
The Metropolitan Area Network (MAN) generally expands throughout a city such as
cable TV network. It can be in the form of Ethernet, Token-ring, ATM, or Fiber
Distributed Data Interface (FDDI).
Metro Ethernet is a service which is provided by ISPs. This service enables its users
to expand their Local Area Networks. For example, MAN can help an organization to
connect all of its offices in a city.
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Backbone of MAN is high-capacity and high-speed fiber optics. MAN works in between
Local Area Network and Wide Area Network. MAN provides uplink for LANs to WANs
or internet.
WideAreaNetwork
As the name suggests, the Wide Area Network (WAN) covers a wide area which may
span across provinces and even a whole country. Generally, telecommunication
networks are Wide Area Network. These networks provide connectivity to MANs and
LANs. Since they are equipped with very high speed backbone, WANs use very
expensive network equipment.
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WAN may use advanced technologies such as Asynchronous Transfer Mode (ATM),
Frame Relay, and Synchronous Optical Network (SONET). WAN may be managed by
multiple administration.
Internetwork
A network of networks is called an internetwork, or simply the internet. It is the
largest network in existence on this planet. The internet hugely connects all WANs
and it can have connection to LANs and Home networks. Internet uses TCP/IP
protocol suite and uses IP as its addressing protocol. Present day, Internet is widely
implemented using IPv4. Because of shortage of address spaces, it is gradually
migrating from IPv4 to IPv6.
Internet enables its users to share and access enormous amount of information
worldwide. It uses WWW, FTP, email services, audio, and video streaming etc. At
huge level, internet works on Client-Server model.
Internet uses very high speed backbone of fiber optics. To inter-connect various
continents, fibers are laid under sea known to us as submarine communication cable.
Internet is widely deployed on World Wide Web services using HTML linked pages
and is accessible by client software known as Web Browsers. When a user requests
a page using some web browser located on some Web Server anywhere in the world,
the Web Server responds with the proper HTML page. The communication delay is
very low.
Internet is serving many proposes and is involved in many aspects of life. Some of
them are:
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 Web sites
 E-mail
 Instant Messaging
 Blogging
 Social Media
 Marketing
 Networking
 Resource Sharing
 Audio and Video Streaming
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