3. Definition of network
network A group of computers and
associated peripheral devices connected by
a communications channel capable of
sharing files and other resources among
several Users.
Sentra Computer
Engineering,
Sep 2013
Melaku A.
4. Some advantages of a network system
Sharing information (or data)
Sharing of software application systems.
Distribution of computing load on computers
Sharing of costly special devices by several computer users.
Ex. Printer ,modem, scanner…
Sentra Computer
Engineering,
Sep 2013
Melaku A.
7. Speed of Data transmission
Narrow band
Telegraph lines
Voice band
Telephone lines
Broad band
Recent technology
8. Types of Networks
Networks may be classified based on a number of parameters:
Geographic location
Control
1. Centralized
I.
II.
Dumb Terminals
Intelligent Terminals
LAN
MAN
WAN
2. Distributed
I.
II.
Client /server
Peer –to –peer
Sentra Computer
Engineering,
Sep 2013
Melaku A.
10. Peer-to-Peer
All the computers are equal and therefore are known as peers
Sentra Computer
Engineering,
Sep 2013
Melaku A.
11. Local Area Network (LAN)
•May be located within a single building or campus
•A LAN can range from simple (two computers
connected by a cable) to complex
LAN
M AN
LAN
WA
Sentra Computer
Engineering,
Sep 2013
Melaku A.
12. Metropolitan Area Network (MAN)
•A larger version of a LAN
•May span several corporate offices or an entire city
M
LAN
Sentra Computer
Engineering,
Sep 2013
Melaku A.
13. WAN (Wide Area Network)
A wide area network (WAN), on the other hand, has no geographical limit.
It can connect computers and other devices on opposite sides of the world.
A WAN is made up of a number of interconnected LANs
Sentra Computer Engineering,
Sep 2013 Melaku A.
14. Network topology
The map of a network
the arrangement or physical layout of computers, cables, and other
components on the network.
Physical layout
Design
Diagram
Map
Sentra Computer
Engineering,
Sep 2013
Melaku A.
16. 1. Star topology
Each computer are connected to a hub
If the central point fails, the entire network goes down
Sentra Computer
Engineering,
Sep 2013
Melaku A.
17. 2. Bus Topology
Referred to as a "linear bus“
a trunk (a backbone or segment)
Sentra Computer
Engineering,
Sep 2013
Melaku A.
18. 3. Ring topology
connects computers on a single circle of cable
Failure of one computer have an impact on the entire network.
Sentra Computer
Engineering,
Sep 2013
Melaku A.
19. 4. Mesh topology
Each computer is connected to every other computer by separate cabling
offers superior redundancy and reliability
Use a lot of cabling
If one cable fails, another will take over the traffic
Sentra Computer Engineering,
Sep 2013 Melaku A.
20. Hybrid topologies
Star bus topology
Star ring topology(star-wired ring)
Sentra Computer Engineering,
Sep 2013 Melaku A.
21. Hardware
NIC
The Network Interface Card (NIC), also known as a network adaptor,
acts as the interface between the computer and the physical network connection
Sentra Computer Engineering,
Sep 2013 Melaku A.
22. Most NICs for desktops are either integrated into the motherboard or are an
expansion card that fits into an expansion slot.
Most NICs for laptops are either integrated into the motherboard or fit into a
PC Card or Express Bus expansion slot.
USB network adapters plug into any available USB port and can be used with
both desktops and laptops.
Sentra Computer
Engineering,
Sep 2013
Melaku A.
24. Modem
Modulates a carrier signal to encode digital information and
Demodulate (digital to signal)
Sentra Computer Engineering,
Sep 2013 Melaku A.
26. Repeater
connects two network segments and broadcasts data between them.
It amplifies the signal, thereby extending the usable length of the bus.
bridge
Acts as an interface between two sets of nodes
Sentra Computer Engineering,
Sep 2013 Melaku A.
27. Hub
center point in a star topology
contains 4, 8, 16 or even more different ports
it broadcasts data received by any of the ports to all
other ports on the hub
Hubs can be
active,
passive or
hybrid
Sentra Computer
Engineering,
Sep 2013
Melaku A.
29. switch
A switch is similar to a bridge,
It has multiple ports.
Can also be seen as a more intelligent hub
Sentra Computer
Engineering,
Sep 2013
Melaku A.
30. Router
used to connect different network segments to internet
unlike a bridge, a router can be used to connect networks
that use different network technologies.
Routers are very commonly found in the hardware
infrastructure that forms the basis of the Internet
Sentra Computer Engineering,
Sep 2013 Melaku A.
33. Coaxial cable
relatively inexpensive, and it was light, flexible, and easy
consists of a core of copper wire surrounded by
insulation, a braided metal shielding, and an outer cover
Designed to carry a high frequency or broadband signal
Sentra Computer
Engineering,
Sep 2013
Melaku A.
34. Fiber optic
Transparent thin fiber made of glass or
plastic for transmitting light
Very fast to transmit data and so expensive
Sentra Computer Engineering,
Sep 2013 Melaku A.
36. Twisted pair cable
consists
of two insulated strands of copper wire
twisted around each other
Types
1. unshielded twisted-pair (UTP) and
2. shielded twisted-pair (STP) cable.
38. UTP
The most popular type of twisted-pair cable
Fast and the most popular LAN cabling
It is cheap and easy to use
Its performance over long distances is not as good as
coaxial cable
Most telephone systems use UTP cable (with the RJ11
connector), and many LANs nowadays also use UTP
(with the RJ45 connector).
Sentra Computer
Engineering,
Sep 2013
Melaku A.
39. STP
Higher quality than UTP, but more
expensive and less popular.
Sentra Computer
Engineering,
Sep 2013
Melaku A.
40. Worlds greatest WAN
Links millions of computer around the globe
Common features
Make information available to others
Search information provided by others
Distribute information & communicate
with others ………
Sentra Computer
Engineering,
Sep 2013
Melaku A.
41. Every site on the Internet has an address
Internet addresses are called URLs (Uniform
Resource Locators)
Eg http://www.sentra.com/basic/list.htm
https://www.facebook.com/ukmxl/photo.htm
Domain types
.edu
.com
.gov
.mil
.net
.org
Country codes
.et
.uk
Sentra Computer Engineering,
Sep 2013 Melaku A.
42. WWW:- newest Internet services that allows to access documents
from any computer from the network
Website:- document address on one computer in the network
Webpage, homepage….
Search engine:- a website used to find (search) data from different
computers on the network
Chat Engine:- social networks used to direct communication
Facebook, msn, Google talk….
E-mail:- most widely used service in the internet
sending text and any multimedia messages to different
users over networks
Sentra Computer
Engineering,
Sep 2013
Melaku A.
Editor's Notes
A switch can also be seen as a more intelligent hub – whereas a hub passes on all data to every port, a switch will only pass data on to the port that it is intended for