S5 MCE. UNIT 3 COMPUTER SCIENCE.pptx

COMPUTER SCIENCE
GS GIKOMERO
S5MCE

INTRODUCTION TO COMPUTER
NETWORK
UNIT 3

Fundamentals of Computer Networks
A computer network connects two or more computers to share data and
resources.
• Nodes: Devices on the network, including hosts (PCs, phones, servers)
and networking hardware (modems, routers, hubs, switches, bridges).
• Connection: Two devices are networked when they can exchange
information.
Types of Connections:
Wired Network: Uses cable media (Ethernet, coaxial, fiber optics) to
connect computers.
Wireless Network: Connects computers using wireless media, such as
radio waves.

Properties of Computer Networks
Easy Sharing of Resources: Allows sharing of internet, files, printers,
and storage.
Performance: Speed of data transmission.
Reliability: Consistent availability of resources.
Scalability: Easily add devices without performance loss.
Security: Protects data with encryption and access controls.
Quality of Service (QoS): Prioritizes traffic for better performance.
Fault Tolerance: Keeps the network running despite failures.

Advantages of Computer Networks
 Enhanced Communication: Improves information sharing.
 Resource Sharing: Allows sharing of devices and services.
 Easy File Sharing: Simplifies file transfers.
 Improved Storage Capacity: Expands storage options.
 Cost Efficiency: Reduces costs through shared resources.
 Security: Protects information and resources.
 Easy Data Backup: Simplifies data backup processes.
Disadvantages of Computer Networking
Lack of Independence: Devices depend on the network, limiting functionality
if it fails.
Security Issues: Higher risk of cyberattacks and data breaches.
Lack of Robustness: Failures can disrupt access to resources.
Complexity: Setup and maintenance can be complicated.
Cost: Initial and ongoing costs can be high.
Performance Issues: Congestion can slow down data transmission.
Dependency on Hardware: Failures in hardware can impact the entire network.

Types of computer networks
A computer network is classified basing on the size of the area covered,
the number of users connected and the number & types of services
available.
These network types are:
Personal Area Network (PAN)
Local Area Network (LAN)
Metropolitan Area Network (MAN)
Wide Area Network (WAN)

a. Personal Area Network (PAN)

a. Personal Area Network (PAN): It is a network that
connects devices like mice, keyboards, printers,
smartphones, and tablets within a range of up to 10
meters.
b. Local area network: It connects computers within a
limited area, such as a home, school, or office building.
It covers a small geographical area and typically uses
Ethernet (IEEE 802.3) as its standard.
A Wireless LAN (WLAN) uses radio waves to
transmit data between wireless devices, while a
traditional LAN connects devices using copper
cabling.
c. Metropolitan Area Network (MAN): It covers a
large area, such as a campus or city, connecting multiple
buildings through wireless or fiber optic links.
d. Wide area network (WAN): It connects multiple
networks that are in geographically separated locations
• WAN network provides connectivity to MANs and
LANs
• The Internet is a large WAN that is composed of
millions of interconnected networks.

Computer Network Concept and
Technology
1. Network metrics: quantitative measurements used to evaluate and
monitor the performance and reliability of a computer network
2. Data Transmission model: transmission mode is used to define the
direction of signal flow between two linked devices
3. Internetwork (Internet, Intranet, Extranet): A network of
networks is called an internetwork, or simply the Internet

1. Network metrics
• Standards of measurement by which efficiency, performance, progress, or
quality of a plan, process can be assessed.
• Network metric are used by a router to make routing decisions.
• When data is sent over a computer network, it is broken up into small
chunks called packets.
• Each packet contains source and destination address information.
• Packets are sent across a network one bit at a time.

Network metrics (cont’d)
a. Bandwidth: Bandwidth is the amount of data that can be transmitted in
a fixed amount of time (b/s,kb/s,Mb/s,Gb/s)
b. Latency: is the time between requesting data and receiving data
c. Throughput: the actual rate at which information is transferred. the
amount of completed work against time consumed and may be used to
measure the performance of a processor, memory and/or network
communications.
d. Error rate: Error rate is the number of corrupted bits expressed as
percentage or fraction of the total sent.
e. Jitter: variation in packet delay at the receiver of information

2. Data Transmission model
The term transmission mode is used to define the direction of signal flow
between two linked devices.
1. Simplex: a single one-way transmission (Keyboard and monitor, computer
and a printer, Listening to the radio)
2. Half-Duplex: data flows in one direction at a time (Walkie-Talkies)
3. Full-Duplex: data flows in both directions at the same time (Telephone)
A to B only
A to B or B to A
A to B and B to A

3. Internetwork
• A network of networks is called an internetwork, or simply the
Internet.
• The Internet, extranets, and intranets all rely on Transport Control
Protocol / Internet Protocol (TCP/IP)
a. An Intranet: is a private computer network that uses Internet
Protocol to securely share any part of an organization’s information
within that organization. Only users inside the organization are only
allowed to access it.

Internetwork (cont’d)
b. An Extranet: is a private network that uses Internet protocols,
network connectivity
Extranet is a private network that enables authorized external trusted
partners to access specific services or information provided by an
organization by using virtual private network (VPN)
c. The Internet: is a global system of interconnected computer
networks that use the standard Internet Protocol suite (TCP/IP) to serve
billions of users worldwide

Local Area Networks (LANs) categories
a) Peer-to-peer (P2P) is a network in which interconnected nodes share
resources among each other without a central device

Advantages of P2P network
It is easier to set up
No need of dedicated server
It is less expensive
It requires less time to configure
and implement it.
Disadvantages of P2P network
A computer can be accessed
anytime
Network security has to be
applied to each computer
separately
Backup has to be performed on
each computer separately
No centralized server is available
to manage and control the access
of data

b) Client-Server Network: In a client-server network,
the client requests information or services from the
server and the server provides the requested
information or service to the client.
It is a communications model in which multiple
clients share the services of a common server.
In a client-server network, resources are controlled
by a centralized network administration

Advantages of client-server network
Centralization of control
Scalability
Easy maintenance
Disadvantages of client-server network
There is a reliance on the central
server, if it fails, no work can be
done
A network manager is required and
this costs money
The server costs money, as does the
network operating system
Servers are powerful, thus
expensive
Lots of network traffic.

Physical Components
A network host or a node is a computer or any other device that is
directly connected to a computer network
i. Network Interface Card (NIC): is a component that allows the
computer to communicate across a network
Wireless Network Interface Card

ii. Media Access Control Address (MAC Address):is a unique identifier
assigned to network interfaces for communications at the data link layer of a
network segment.
iii. Modem: is a hardware device that enables a computer to send and receive
data over a telephone line or a cable or satellite connection
The word “modem” is derived from the term “Modulator - Demodulator.”
its main functions are:

modulator takes the input signals which contains the information to be
transmitted and combines it with carrier signal to produce a modulated
signal that can be transmitted over a communication channel.
demodulator takes the modulated signal as input and separates it into its
original components.
Modem is used to transmit digital information via analog systems
Two types of modem are internal and external

iv. RJ 45 Connector and Port: A registered jack (RJ) is a standardized
physical network interface used for network cabling, wiring and jack
construction.
RJ 45 is eight-wire connector used for Ethernet connection in LANs
RJ 45 connector is connected to a device through Ethernet port.

NETWORK DEVICES /CENTRAL DEVICES
Network devices are devices used to connect, manage and facilitate
communication between devices in a computer network
1. Hub: is a basic network device used to connect multiple devices in a
network. It receives data packets on one port and send them to all
connected devices.

2. Switch: is a device that connects multiple devices within a network. It
receives the data packets and forwards them to the correct destination
device. It operates in data link layer of OSI model.
How does a network switch work?
Once a device is connected to a switch, the switch notes its MAC address
and uses the MAC address to identify which device’s outgoing packets are
being sent, and where to deliver incoming packets.
When a packet enters the switch, the switch reads its header, then matches
the destination address and sends the packet out through the appropriate
ports that lead to the destination devices.

3. Network bridge: is a networking device used to divide a LAN into multiple
segments.
• It operates in data link layer of OSI model
• It stores the MAC addresses of available PCs in a network
• It reduces the network traffic
• It has only two ports which enables it to divide a network into two
segments (segment 1 and segment 2)
This is how a network bridge works

4. Access Point is connected to a switch using UTP cable, therefore it can
provide access to the rest of the network. Instead of providing copper cabling
to every network host, only the wireless access point is connected to the
network with copper cabling and spread radio waves to the rest of network
A wireless access point (WAP) is a networking device that allows wireless-
capable devices to connect to a wired network

Network Transmission Medium
Network transmission medium is the physical mean of communication
between network computers.
Data transmission media are the physical materials used to transmit data
between computers on a network.
Example:
Copper wire (to carry electrical signals)
Fiber optic (to carry light signal
Wireless/ radio frequency (to carry electromagnetic waves through
space)

Two main types of data communication media
Bounded or Guided media: which transmit signals by sending electricity or
light over a cable wire (twisted cables, Coaxial cables and fiber optic cables)
Unbounded media or unguided media: which transmit data through the air,
radio waves, layer or infrared signal and satellite-based microwaves, etc.

1. Guided/bounded transmission media
a. Coaxial cable: is a type of cable that has an inner
conductor surrounded by an insulator and a conductive
shielding to avoid signal interference
Types of coaxial cable
Thicknet or 10BASE5 which is used in networks and
operated at 10 Mb/s with a maximum length of (500 m)
Thinnet 10BASE2: which is used in networks and
operated at 10 Mb/s with a maximum length of 607 ft.
(185 m)

b. Twisted-pair copper cabling
Twisted pair copper cabling is a type of communications cable in which two conductors of a
single circuit are twisted together for the purposes of improving electromagnetic compatibility
TYPES OF TWISTED PAIR CABLES
a. Unshielded twisted-pair (UTP): they have two conductors that are generally made up of
copper and each conductor has insulation.
A crossover cable: is a type of Ethernet cable used to connect computing devices together directly
and is used to connect two devices of the same type, e.g. two computers or two switches to each
other, …..
A straight-through cable: is used to connect different types (computer to a router, a router to a
switch, …)

b) Shielded twisted-pair (STP): it is similar to UTP cable but with an additional
layer of shielding to provide extra protection against electromagnetic
interference(EMI) and radio frequency interference (RFI)
FIBER OPTIC CABLE/ OPTICAL FIBER refers to the way of transmitting
information by using a total internal reflection principle of light. Fiber optic cables
carry light signals

Advantages of fiber optic
They are not affected by radio interference or cross talk (unwanted signals in a
communication channel)
They can transmit signals over a long distance up to 2000
They can carry information at high rate speed
They are more secured
Low transmission loss
Data can be transmitted digitally
They are more resistant to adverse weather conditions.
Their download and upload speeds are equal
They carry a large amount data

2. Unguided/ unbounded transmission media
Unguided media transport electromagnetic waves without using a physical
conductor and this is done through wireless communication.
a.Wireless Transmission: It is a method of
communication that relies on the use of wireless signals to transmit data
Wireless transmission works by using electromagnetic waves to transmit data
without the need for physical cables or wires.
The process involves a with transmitter and a receiver.

The transmitter takes the information to be transmitted and converts it into
electromagnetic waves.
The electromagnetic waves are then propagated through the air, water, or
vacuum, depending on the specific wireless transmission medium being used.
These waves carry the encoded information and travel through space until
they reach the receiver.
The receiver, equipped with an antenna, picks up the electromagnetic waves
and converts them back into the original form of the transmitted information
(demodulation)

Wireless transmission can occur over various frequencies and
can be used for different purposes.
For example:
Wi-Fi uses radio waves to transmit information between
devices and a router
Cellular networks utilize radio waves to enable wireless
communication between mobile devices and base stations
Satellite communication relies on microwaves to transmit
signals between satellites and ground stations.
Remote controllers commonly use infrared (IR) waves to
transmit signals to the device they control, such as a TV or
DVD player.

Notice: Infrared waves are relatively inexpensive to
produce, have low power requirements, and are effective
for short-range communication within a room
Additionally, infrared signals are less likely to interfere
with other devices compared to radio waves because
Infrared signals have high frequencies and cannot
penetrate walls.
The disadvantages of using infrared
● Infrared signals cannot be used for long distance
communication.
● Infrared waves cannot be used outside of a building
because sun's rays contain infrared waves that can
interfere with communication.

1. Radio waves are a form of electromagnetic radiation that enable wireless
communication and broadcasting.
Transmitter: In radio communication, a transmitter generates radio waves and
sends them through an antenna. The antenna radiates the radio waves into
space. Once the radio waves are emitted by the antenna, they travel through
space in all directions (atmosphere, vacuum, or other mediums)
Receiver: receiver demodulates the received radio waves, extracting the
original information that was encoded onto the waves.

 Cellular networks rely on radio waves to enable wireless communication
between mobile devices and cell towers.
 Cellular networks are divided into cells, which are geographic areas covered
by individual cell towers or base stations.
 Each cell tower serves a specific area and communicates with mobile devices
within its range.
 Cellular networks use radio frequency (RF) connections to transmit and
receive data between mobile devices and cell towers.
 Radio Access Network (RAN) like cell towers, antennas, and other equipment
that transmit and receive radio waves.
 Mobile devices, such as smartphones, have built-in antennas that transmit
and receive radio waves.
 When a user makes a call, sends a text message, or accesses the internet, the
device sends signals to the nearest cell tower using radio waves

Bluetooth
Bluetooth is a wireless technology used for exchanging data
between devices over short range.
Bluetooth relies on short-range radio frequency, and any device that
incorporates the technology can communicate as long as it is within
the required range.
The difference between Bluetooth and infrared is that Bluetooth
allows communication when there is a barrier or a wall.
Before devices can communicate, they need to be paired. Pairing
involves establishing a secure connection between two Bluetooth
devices. During the pairing process, devices exchange encryption
keys to ensure secure communication.

Wi-Fi (Wireless Fidelity)
Wi-Fi is a wireless network technology which uses radio waves to connect
devices to the internet or other networks without the need for physical
cables.
It supports IEEE802.11b Ethernet standard.
The Access Point is used to connect devices and it acts as the central
device for Wireless LAN
To connect to a Wi-Fi network, a device needs a Wi-Fi adapter or a built-
in Wi-Fi capability.
The device scans for available Wi-Fi networks, and the user selects the
desired network and enters the appropriate password if required.
Once connected, the device can access the internet and communicate with
other devices on the same network.

Cellular network generations
1. First Generation (1G): was introduced in the late 1970s and early 1980s
and it used analog technology for voice communication and had limited
capacity and coverage
2. Second Generation (2G): emerged in the 1990s and introduced digital
technology, enabling more efficient voice communication and the
introduction of text messaging (SMS).
3. Third Generation (3G): was introduced in the early 2000s and brought
significant improvements in data transmission speeds, enabling services
like mobile internet access, video calling, and multimedia messaging.
4. Fourth Generation (4G): it was introduced in the late 2000s, enabled
faster internet browsing, video streaming, and advanced mobile services.
5. Fifth Generation (5G): is the latest generation of cellular networks, with
deployments starting in the 2010s. It offers significantly faster speeds. it
enable advanced applications such as autonomous vehicles, remote surgery,
and massive IoT (Internet of Things) connectivity.

Location tracking through Global Positioning System
GPS is a navigation system that uses network of 24 U.S satellites to
determine the precise location of a receiver on Earth.
HOW GPS WORKS
All 24 GPS satellites circle the planet twice a day in a very specific orbit.
During their travels, the satellite sends signal information to Earth.
A GPS receiver receives the information from all available satellites and
calculates the GPS receiver’s exact location by comparing the time that a
signal was transmitted by the satellite to the time the receiver receives the
signal.
This provides the distance that the satellite is from the receiver.
By using this difference from several satellites, the GPS receiver is able to
determine the receiver’s position with a high degree of accuracy and display
on a map or chart.
In order to provide an accurate 2D position consisting of latitude and
longitude (and to track movement), GPS receivers require at least three
GPS satellites signals to be received.
If there are four or more satellites in view, then the 3D position of the GPS
receiving unit (latitude, longitude, and altitude) can be determined.

IP Addresses
An IP address is an address used to uniquely identify a device on a computer
network.
IP Versions
There are two versions of IP address:
IP version 4
IP version 6

(a) Internet Protocol version 4 (IPv4)
IPv4 is the fourth version of IP and has been in use since the early days of
the internet.
It is the common used IP address
Structure of IP address
An IP address is a series of 32 binary bits grouped into four octets
separated by dots (4-8-bits bytes)
Ex: 192.168.1.5: 11000000.10101000.00000001.00000101
. . .
Once a host receives an IP address, all 32 bits are received by the
network interface card NIC.
11000000 10101000 00000001 00000101
Octet 1 Octet 2 Octet 3 Octet 4

Parts of IP address
IP address is made up two parts:
Network part/ network address/ network ID
This is the portion of the IP address that identifies the specific network to
which the device belongs.
Host part/ host address/ host ID
this is the portion of the IP address that identifies the specific device/ host
within the network.

Classes of IP version 4
There are five classes of available IP ranges:
Common used classes
Class A
Class B
Class C
Notice: class D and E are reserved for multicasting (the method of sending
data packets to a group of devices on a network simultaneously)

Class A
In class A, the first bit of the first octet (byte) is
always 0. 0xxxxxxx where x stand for any value (either o
or 1)
Minimum: 00000000=0 Maximum: 01111111=127
Range: the octet 1 is ranging between 0 and 127
127.x.x.x is reserved for the loopback/ localhost
(a special address range reserved for testing and
communication within a device itself)
Example: 127.0.0.1 is the common loopback address
In class A, octet 1 is network ID and others are for host
ID (N.H.H.H)

Broadcast address: is a special IP address used to transmit message and
data packets to all devices within a network.
In class A network, the broadcast address would have the last three octet
as 255.
Example: class A with IP address of 10.0.0.0, the broadcast address will
be 10.255.255.255

Class B
In class B, the first bit of first byte is always 1 and
the second bit of first byte is always 0
10xxxxxx where x stand for any value (either o or 1)
Minimum: 10000000=128 Maximum: 10111111=191
In class B, octet 1 and octet 2 are for network ID and
other are for host ID (N.N.H.H)
In class B network, the broadcast address would have
the last two octets as 255.
Example: class B with IP address of 135.0.0.0, the
broadcast address will be 135.0.255.255

Class C
In class C, the first bit of first byte is always 1, the
second bit of first byte is always 1 and the third bit
of the first octet is always 0
110xxxxx where x stand for any value (either o or 1)
Minimum: 11000000=192 Maximum: 11101111=223
In class C, octet 1, octet 2 and octet 3 are for network
ID and the last is for host ID (N.N.N.H)
In class C network, the broadcast address would have
the last octet as 255.
Example: class C with IP address of 200.0.0.0, the
broadcast address will be 200.0.0.255

Subnet mask
A subnet mask is used to determine which portion of the address belongs to
the network address and which portion belongs to the host address.
Notice: Class A, B, and C networks have default masks (natural masks)
Class A: 255.0.0.0
Class B: 255.255.0.0
Class C: 255.255.255.0

(b) Internet Protocol Version 6 (IPv6)
IPv6 (Internet Protocol Version 6) also called IPng (Internet Protocol next
generation) is the newest version of the 128 Internet Protocol reviewed to
replace the current version of IPv4
IPv6 is a 128-bit address in eight 16-bitblocks separated by colons
Example: 3ffe:1900:4545:3:200:f8ff:fe21:67cf
Features of IPv6
Supports source and destination addresses that are 128 bits long
No more NAT (Network Address Translation)
Auto-configuration
No more private address collisions.
Uses Flow Label field to identify packet flow for Quality of
Service handling by router.
Allows the host to send fragments packets but not routers.
Does not require manual configuration or DHCP

Three types of IP v6 addresses
Unicast addresses: a packet is delivered to one interface.
Multicast addresses: a packet is delivered to multiple interfaces.
Anycast addresses: a packet is delivered to the nearest of multiple
interfaces (in terms of routing distance).

IP ADDRESS ASSIGNMENT
1) Static IP assignment:
The manual configuration of a host in a network, allows to assign the static
IP address and the following information has to be specified
IP address: identifies the computer on the network
Subnet mask: is used to identify the network on which the computer is
connected
Default gateway: identifies the device that the computer uses to access
the Internet or another network
Optional values: such as the preferred Domain Name System (DNS)
server address and the alternate DNS server address
2) Dynamic IP configuration:
A DHCP (Dynamic Host Configuration Protocol) server automatically
assigns IP address to host.
It simplifies the addressing process.
DHCP server can automatically assign to a host an IP addres, Subnet
mask, Default gateway and Optional values, such as a DNS server address.

SOME COMMON PROTOCOLS
Hypertext Transfer Protocol (HTTP): Enables communication and data
transfer between web browsers and web servers.
Transmission Control Protocol/ Internet Protocol(TCP/IP): Provides
the foundation for internet communication, including addressing, routing,
and packet delivery
URL (Uniform Resource Locator). It is a webpage address which is a
formatted text string used by web browser, email client or other software to
identify a network resource on the internet. It consists of three parts
named Network protocol, Domain name or address and file or resource
location.
File Transfer Protocol (FTP): Facilitates file transfer between a client
and a server
Address Resolution Protocol(ARP): Resolves IP addresses to MAC
addresses on a local network
Domain Name System (DNS): Translates domain names to IP addresses,
enabling human-readable web addresses
Dynamic Host Configuration Protocol (DHCP): Assigns IP addresses
and network configuration parameters dynamically to devices on a network

Simple Mail Transfer Protocol (SMTP): Transfers email messages
between mail servers
Secure Shell (SSH): Provides secure remote access and secure file transfer
capabilities
Internet protocol Security (IPsec): Ensures secure communication by
authenticating and encrypting IP packets
Border Gateway Protocol (BGP): Exchanges routing information
between autonomous systems on the internet
Network Time Protocol (NTP): Synchronizes the time of devices on a
network.
Internet Message Access Protocol (IMAP): Retrieves email messages
from a mail server
User Datagram Protocol (UDP): Provides a connectionless and
lightweight protocol for fast data transmission.
Secure Sockets Layer/Transport Layer Security (SSL/TLS): Encrypts
data transmitted over a network to ensure secure communication.

Internet Control Message Protocol (ICMP): Facilitates network
error reporting and diagnostic functions.
Virtual Private Network (VPN): Establishes secure connections
over public networks, enabling remote access and private
communication.
Network File System (NFS): Allows remote file access and sharing
over a network.
Simple Network Management Protocol (SNMP): Manages and
monitors network devices and gathers information for network
management.
Internet Group Management Protocol (IGMP): Manages
multicast group memberships on a network.
Ethernet: A widely used protocol for wired local area networks
(LANs) that defines how data is transmitted over the physical
network.

Commands used to verify computer connection on a
network
1) Ping command: is commonly used to test connections between
computers.
It is a simple but highly useful command-line utility used to determine
whether a specific IP address is accessible.
2) IPconfig command is used to find out your current local IP
address, default gateway, TCP/IP settings and more.
ipconfig/all: it displays all current IP information for all adapters.
ipconfig /release: Used to release current IP information and
obtain a new IP Address from the DHCP server.
ipconfig /renew: it is used to renew IP Address if you have it set to
obtain IP Address automatically.

Network Resource Sharing
Firstly, you need to determine which resources will be shared over the
network and the type of permissions users will have to the resources.
Any device which is connected to a host /node is called a Network Peripheral
in other word network peripheral is any device that is indirectly connected to
the network.
Examples of network peripheral are: printer, scanner

NETWORK TOPOLOGY
The network topology describes the configuration of network or the physical and
logical arrangement of nodes and connections on a network.
Classifications of network topologies
Physical topology: the arrangement of network nodes and their physical
connections.
Signal topology: the paths that signals take while they traverse the network.
Logical topology: the way data signals pass from one device to another.
Types of network topologies
Bus topology
Ring topology
Star topology
Mesh topology
Tree topology
Hybrid topology

BUS TOPOLOGY
Bus topology is a type of network topology in which all devices are connected to
a single cable
 Drop lines are the cables that connect to the primary cable (the bus)
 Taps are the individual connectors
Features:
It transmits data only in one direction
Every device is connected to a single cable
Advantages of busTopology Disadvantages of bus Topology
 It is cost effective
 Cabling is less required
 Used in small networks
 It is easy to understand
 Easy to expand joining two cables together.
 Cables fails then whole network fails
 The lower the number of nodes, the higher the performance it has
 Cable has a limited length
 It is slower than the ring topology.

RING TOPOLOGY
Ring topology is a type of network configuration where each device is
connected other two devices in a circular manner, forming a closed loop.
Features:
Each networked computer is connected to two others
Data travel from one device to the next until they reach their destination
single ring topologies allow data to travel only in one direction
Dual ring topologies allow data to travel in both two directions
Advantages of ring Topology Disadvantages of ring Topology
 No traffic in data transmission
 Cheap to install and expand
 Troubleshooting is difficult in ring topology
 Adding or removing the computers disturbs the network activity
 Failure of one computer disturbs the whole network.

STAR TOPOLOGY
Star topology is a network topology in which each network component is physically connected to a
central node such as a router, hub or switch.
Features:
Every node has its own dedicated connection to the hub
Hub acts as a repeater for data flow
Can be used with twisted pair or coaxial cable
Advantages of star Topology Disadvantages of star Topology
 Fast performance with few nodes and low network traffic
 Hub can be upgraded easily
 Easy to troubleshoot
 Easy to setup and modify
 Cost of installation is high
 Expensive to use
 If the hub fails then the whole network is stopped
 Performance is based on hub capacity

MESH TOPOLOGY
a network configuration where each device connects directly to multiple other
devices.
Partial mesh topology: here only some nodes connect directly to one another
Full mesh topology: here each node is connected directly to all the other nodes
Advantages of mesh Topology Disadvantages of mesh Topology
 Each connection can carry its own data load
 It is robust
 Fault is diagnosed easily
 Provides security and privacy.
 Installation and configuration is difficult
 Cabling cost is more
 Bulk wiring is required

TREE TOPOLOGY
Tree topology is a combination of Bus and Star topology.
Advantages of tree Topology Disadvantages of tree Topology
 Extension of bus and star topologies
 Expansion of nodes is possible and easy.
 Easily managed and maintained.
 Error detection is easily done.
 Heavily cabled
 Costly
 If more nodes are added maintenance is difficult.
 Central hub fails, network fails.

HYBRID TOPOLOGY
Hybrid topology is a type of network topology in which two or more
different topologies are combined in a network.
Advantages of hybrid Topology Disadvantages of hybrid Topology
 Reliable
 Scalable (easy to add new component)
 Flexible
 Effective
 It is Complex to Design
 Costly Infrastructure

S5 MCE. UNIT 3 COMPUTER SCIENCE.pptx

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