NETWORKS, INTERNET
and E COMMERCE
Computer network
In information technology, a computer network, also
called a data network, is a series of points, or nodes,
interconnected by communication paths for the
purpose of transmitting, receiving and exchanging
data, voice and video traffic.
Computer network
• Network devices including switches and routers use
a variety of protocols and algorithms to exchange
information and to transport data to its
intended endpoint. Every endpoint (sometimes
called a host in a network has a unique identifier,
often an IP address or a Media Acess control
address, that is used to indicate the source or
destination of the transmission. Endpoints can
include servers, personal computers, phones and
many types of network hardware.
Computer network
 Wired and wireless technologies
 Networks may use a mix of wired and wireless technologies.
Network devices communicate through a wired or wireless
transmission medium. In wired networks, this may consist of
optical fiber or coaxial cable or copper wires in the form of
a twisted pair. Wireless network pathways include computer
networks that use wireless data connections for connecting
endpoints. These endpoints include broadcast radio, cellular
radio, microwave and satellite.
Computer network
Networks can be private or public. Private networks
require the user to obtain permission to gain access.
Typically, this is granted either manually by a network
administrator or obtained directly by the user via a
password or with other credentials. Public networks
like the Internet do not restrict access.
• Networks may also be categorized by the
scope of their domains.
TYPES OF
COMPUTER
NETWORK
1. Wide area network interconnect multiple
LANs, and
2. Metropolitan area network interconnect
computer resources in a geographic area.
3. Storage area network interconnect storage
devices and resources. Networks may also
be divided into subnetworks, also called
subnets.
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TYPES OF
COMPUTER
NETWORK
• Network protocols and standards specify
exactly how data should be transmitted and
received.
1. Mod ern, packet switch netwo rks use
protocols to establish a standard means of
communication.
2 . T h e E th e r n e t s ta n d a r d e s t a b l i s h e s a
common language for wired networks to
communicate.
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TYPES OF
COMPUTER
NETWORK
• A network's capacity -- that is, how much
traffic it can transmit at any one time -- is
measured in terms of bandwidth. Bandwidth
is quantified by the theoretical maximum
number of bits per second that can pass
through a network device. Throughput is a
measure of the actual speed of a successful
transmission after accounting for factors like
latency,
processing
power
and
protocol overhead.
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Network Characteristics
The following characteristics are also used to categorize different types of networks:
1.
TOPOLOGY - T h e g e o m e t r i c a r r a n g e m e n t o f a c o m p u t e r s y s t e m . C o m m o n
topologies include a bus, star, and ring.
2.
PROTOCOL -defines a common set of rules and signals that computers on the
network use to communicate. One of the most popular protocols for LANs is
called Ethernet
3.
ARCHITECTURES -refer to either hardware or software or to a combination of
both.
4.
COMPONENTS

Computers on a network are sometimes called nodes.

Computers and devices that allocate resource., for a network are called servers.
Types of
Network
Topology
1.
BUS Topology is a network type in which
every computer and network device is
connected to single cable. When it has exactly
two endpoints, then it is called Linear Bus
topology.
2.
RING Topology forms a ring as each computer
is connected to another computer, with the
last one connected to the first. Exactly two
neighbors for each device.
3.
STAR Topology is where all the computers are
connected to a single hub through a cable. This
hub is the central node and all others nodes
are connected to the central node.
4.
TREE Topology (Hierarchy Topology) has a root
node and all other nodes are connected to it
forming a hierarchy. It should at least have
three levels to the hierarchy.
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5. MESH Topology i s a p oint -to -point
connection to other nodes or devices. All
the network nodes are connected to
each other. Mesh has n(n-1)/2 physical
channels to link n devices.
Types of
Network
Topology
There are two techniques to transmit data
over the Mesh topology, they are
1.
Routing - the nodes have a routing
logic,
as
per
the
network
requirements. Like routing logic to
direct the data to reach the
destination
using the
shortest
distance.
2.
Flooding - the same data is
transmitted to all the network nodes,
hence no routing logic is required.
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Backbone
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M i l
Bus
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Point-to-Point
Network protocol defines rules and
conventions for communication between
network devices. Network protocols include
mechanisms for devices to identify and
make connections with each other, as well
as formatting rules that specify how data is
packaged into messages sent and received.
Some
protocols
also
support
message acknowledgment and data
compression designed for reliable and/or
high-performance network communication.
1.
The Internet Protocol family contains a set of
related (and among the most widely used network
protocols.
2.
Wireless network protocols designed for use on
wireless networks must support roaming mobile
devices and deal with issues such as variable data
rates and network security.
/ /
 The term protocol refers to a well known set of rules and formats to be
used in order to perform a task. For
example, a task of communicating
between processes.
Network
protocol
 Parts of a protocol:
 A specification of a sequence of
messages that must be exchanged.
 A specification of the format of the
data in the messages.
 Existence of well-known (standard)
protocols
enables
the
separate
components of the distributed systems
to be developed independently in
different languages and on different
platforms.
 Ports are destination points within a host computer.
 Processes are attached to the ports, enabling them to
communicate.
 Transport layer addresses are composed of network
address of the host computer and a port number.
 In the Internet every host is assigned a unique IP number
which is used in routing.
 In an Ethernet each host is responsible for recognizing
that the messages meant for it.
 No single networking technology can satisfy all
requirements.
 Universal interconnection is desired.
 Protocols allow communication between nodes
without understanding underlying mechanisms.
 Internetworking is the process by which a group
of disparate, heterogeneous networks can be
linked to form a single logical network.
I• T h e I n t e r n e t i s j u s t s u c h a c o l l e c t io n .
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 Routing is the mechanism used to transfer
data between networks to reach the correct
ea.
destination.
• A net wo r k ope rat i ng syst em (NOS ) is a com p ute r operating
syst am
system
that
is
designed
primarily
to
support workstation,
loconal computer, a n d , i n s o m e
i n s t a n c e s , o l d e r terminal t h a t a r e c o n n e c t e d o n a l o c a l a r e a
network
(LAN).
Artisoft's
LANtastic,
Banyan
VINES,
Novell's NetWarf, 1 and Microsoft's LAN Manager are examples
of network operating systems. In addition, some multi -purpose
operating
systems,
such
as
Windows
NT
and
Digital's OpenVMS come with capabilities that enable them to
be described as a network operating system.
WHAT IS ECOMMERCE
Commonly known as Electronic Marketing.
"It consist of buying and selling goods and services over
an electronic systems Such as the Internet and other
computer networks."
"E-commerce is the purchasing, selling and exchanging
goods and services over computer networks (Internet)
through which transaction or terms of sale are performed
Electronically.
;mt..
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E-COMMERCE TECHNOLOGIES
E_ Internet, intranets, and extranets - network
infrastructure or foundation of e-commerce.
Customers - secure information, marketing,
transaction, processing, and payment services.
Trading and business partners - exchange information
and accomplish secure transactions; including
electronic data interchange (EDI), supply chain,
financial systems and databases.
Company employees - resources to communicate and
collaborate in E-Commerce work activities.
Information system professionals and end users manage the content and operations of the websites
and other E-Commerce resources
E-commerce businesses may also employ some or all of the followings:
Online shopping web sites for retail sales direct to consumers
Providing or participating in online market places, which process third-party
business-to-consumer or consumer-to-consumer sales
Business-to-business buying and selling;
Gathering and using demographic data through web contacts and social media
Business-to-business (B2B) electronic data interchange
Marketing to prospective and established customers by e-mail or fax (for example,
with newsletters)
Engaging in retail for launching new products and services
Online financial exchanges for currency exchanges or trading purposes.