Transcript CSCI-1305 Introduction To Information Technology

Introduction to
Networks
What is a Network?
• A network is an interconnected
system of things or people
•
•
•
•
•
•
•
•
Religions
Business contacts
Snail Mail
Social Media
Broadcasting - NBC, CBS, ABC, PBS
Transportation (air traffic control, highways & rail)
Cellular phone service
…and of course computer based (internet)
• Networks let people share resources, devices,
information, software, and data.
• Networks can be simple, or complex, and network
components can interact in different ways.
Computing before Networks
• In the early years of the computer revolution, most
computers functioned as stand along units.
• And then . . .
Bob Metcalfe had an Idea
• In 1976, Bob Metcalfe had an idea for transporting
data between computers.
• His idea has become a key element in just about
every computer network including the Internet.
• He called his idea Ethernet.
And so . . .
• In the global society we live in, networks connect
people and resources
• Hardware and software are required to make this
happen
• Networks can be simple or complex
• The Internet is the largest network in the world
Ethernet Technology
• Ethernet is the most widely used standard for wired
networks. This standard controls how adapter
cards, routers, and modems share access to
cables and phone lines. The standard also dictates
how devices transmit data.
Cables, Connectors, Ports
Wired networks have cables that connect
network devices through ports. Networks could
use the following types of cables.
• Twisted pair (lowest rate of data transfer)
• Coaxial
• Fiber optic (fastest rate of data transfer)
Are all Networks the Same?
• Networks exist in many variations because each
one is constructed from a collection of
technologies.
• Networks can be classified according to their size
and geographic range or scope.
Wired Networks
• Data in a wired network travels from one device to
another over cables. Wired networks tend to be
more secure and transmit data faster than wireless
networks.
Wireless Networks
• Data in a wireless network travels through the air.
Wireless networks are more convenient, but can be
less secure.
In information technology, a network
is the combination of hardware,
software, cables, and signals that
allows people and computers to
communicate with each other and
other electronic devices.
Nodes
What is a Node?
• In a network, a node is a connection point. In
general, a node has programmed or engineered
capability to recognize and process or forward
transmissions to other nodes.
Computer Networks – Nodes
• Node – Client
•
•
•
•
•
•
•
Printers
Desktops
Laptops
Copiers
Network storage devices
Routers
Anything that can connect to a network
•
•
•
Cell phone
GPS device
IPOD/PSP/XBOX/PS3/Tivo/DVR/Slingbox…
Identify Nodes
Networks Need Hardware and
Software to Make Connections
• Simple software built into a computer will connect a
home network
• Sophisticated software is needed for larger and
more complex networks
Network Interface Card (NIC)
• A circuit board with
special electronic
circuits that connects
a computer to a
network
• Smaller laptops or tables may use a wireless network
card
Communications Hardware
• To connect to a network, your computer will need a
network interface card (NIC), which can be wired or
wireless
Hub or Switch
• A device that provides
a central point for
cables in a network.
Most networks today use switches, which transfer
data only to the intended recipient.
• Switches are more commonly used than hubs
because switches transfer data only to the intended
devices.
Communications Hardware
Hubs and switches provide a central point for network
cables. Hubs transfer all data to all devices, and switches
transfer data only to specified recipients. Most modern
networks use switches rather than hubs.
Router
• A device that connects two or more networks and
directs, or routes, the flow of information along the
networks.
Communications Hardware
A router manages network traffic by evaluating
messages and routing them on the best path to their
destination.
Communications Hardware
• A digital modem sends and receives data and
information to and from a digital line. Many
modems today include built-in Wi-Fi connectivity.
Network Hardware Devices
• Wireless access point – Lets wireless device
connect to a wired network
• Router – Sends data between networked
computers
• Broadband modem – Connects a computer to the
Internet
Mobile Computing
Smartphones, laptops, tablets, and other handheld
devices can connect wirelessly to networks to share
data and services, which is known as mobile
computing.
Identify NICs,
Switch, Wireless Access
Points, Mobile Computing,
and Router
Why no modem?
Network Architecture
Network architecture determines how networked
computers interact with one another.
Typically, one of two architectural models are used:
• Peer-to-peer
• Client/Server
Domain vs. Peer
Networks can be domain-based or peer-to-peer.
• Domain-based networks have a domain controller
such as a server, that regulates access to the
network.
• In a peer-to-peer network each computer is equal on
the network and controls access to its own resources.
Peer-to-Peer is best suited for networks with
10 or fewer computers
Individual
computers
may maintain
their own
files, but
share
resources
such as
printers and
scanners.
Client Server
Each computer or device on the network is called a
client. The clients make requests of the server for
services, like access to a software program, a
database, the Internet, or a printer.
A client server is one central computer (the server)
controlling access to network resources.
Wireless Networks
In addition to domain vs. peer-to-peer, networks can
be wired and wireless. Wireless networks
communicate via signals through the air, connecting
devices without the use of cables.
Wi-Fi Hotspot
A Wi-Fi (wireless fidelity) network uses radio signals
to connect computers and devices.
Tethering and Mobile Hotspots
You tether (connect) your mobile phone to your
computer, using a USB cable or Bluetooth, and then
turn on your mobile phone’s tethering feature.
Client/Server or
Peer-to-Peer?
Identify Hotspots,
and Tethering Areas
PAN (Personal Area Network)
• Is a network that connects personal digital devices
within a range of about 30 feet.
PANs work without the
use of wires or cables.
Bluetooth is an example
of a PAN.
Where could a PAN be
located in this diagram?
Networks May Use a Combination of
both Wired and Wireless
Technologies
Identify wired and
wireless
Types of Networks
• In communication networks, a topology is a schematic
description of the arrangement of a network, including its
nodes and connecting lines.
• The topology of a network is a diagram of the network and the
way it physically connects.
Network Topology
Network topology is the physical system of
interconnections of the elements of a computer network
(Links, Nodes, Clients, etc.) The system of interconnected
things on a computer network are referred to as nodes.
Star Topology
Star topology is the most common topology used in
today’s workplace.
North Greenville University in Tigerville uses star
topology.
Bus Topology
Bus topology is where in a computer
network, a bus is a transmission path on
which signals are dropped off or picked up at
every device attached to the line.
Ring Topology
A ring is a network topology or circuit
arrangement in which each device is
attached along the same signal path to two
other devices, forming a path in the shape
of a ring.
Mesh Topology
Wireless
Topology
A wireless Internet service provider (WISP) is
an Internet service provider (ISP) that allows
subscribers to connect to a server at
designated hot spots (access points) using a
wireless connection such as Wi-Fi.
Identify Ring Topology,
Star Topology, and
Wireless Topology
LAN – Local Area Network
• A local area network (LAN) connects computers
and devices in a limited area, such as a home, an
office building, an office complex, or a school
• Each computer or device on the network is called a
node
• Networks help companies save money by
facilitating resource sharing.
WAN – Wide Area Network
• A wide area network (WAN) covers a large area. A
WAN is appropriate for a state, country, or other
large area where data needs to be transmitted over
significant distances.
• WANS combine multiple connection technologies,
such as telephone lines, cables, and radio waves.
• A WAN can be one large network, or a WAN can
consist of a series of interconnected LANs.
• Multi-nations companies, governments, retail
chains might all use WANS.
• The Internet is the world’s largest WAN.
LAN or WAN?
The Internet . . .
• Is a collection of personal, local, regional, national,
international, and multinational computer networks.
It is the largest network in the world.
The Internet is Many Networks
all Linked Together.
• They share data and tasks. The Internet carries
voice, data, video, and graphics.
Artist rendering
of the Internet
The Internet Backbone . . .
• The essential infrastructure of the Internet, is owned by
several telephone and communications companies
around the world such as AT&T and Verizon.
Network Service Providers
• Backbone links and routers are maintained by
network service providers (ISPs). No single entity
controls or owns the Internet.
Internet Service Provider (ISP)
• Is a company that offers Internet access to
individuals, businesses, and smaller ISPs.
Connecting to a Network
• Computers need specific network hardware, services, and
standards to connect to a LAN or a WAN
• Connecting to the Internet often requires services from an
Internet service provider
• All communication technologies need global standards so
they can understand one another
Network Standards
• Computers need a common language to
communicate over networks. Network hardware
and software must work together, regardless of
who made them or where they are located.
• To ensure that any computer in any part of the
world can connect to any network, organizations
such as ANSI and IEEE propose, develop, and
approve network standards
Network Standards
Network standards specify the way computers access a network,
the types of hardware used, data transmission speeds, and the
types of cable and/or wireless technology used.
Current Network Standards
How Networks Work
•
•
•
Networks connect computers and digital devices to share
resources and data.
Networks need hardware to transmit data
Networks let you share resources and data to get your work
done
Bandwidth
Networks transmit data using the information
“Roads” and “highways.” Smaller roads carry
less information than the larger highways.
Bandwidth is the common term used to describe
information carrying capacity.
Broadband refers to high-capacity channels (like
the superhighways.)
Narrowband refers to slower channels with less
capability such as dial-up (like the back roads.)
Networks can also be described by their
geographical area
PAN
Personal Area Network
• PAN refers to the networking of personal digital
devices within a range of about 30 feet. For
example, a PAN can transmit data wirelessly from a
notebook computer to a media player.
LAN
Local Area Network
• A local area network (LAN) connects computers
and devices in a limited area, such as a home, an
office building, an office complex, or a school
• Each computer or device on the network is called a
node
• Networks help companies save money by
facilitating resource sharing.
NAN
Neighborhood Area Network
• A NAN provides connectivity within a limited
geographical area, such as in a city’s downtown
area.
MAN
Metropolitan Area Network
• A MAN is a public high-speed network capable
of voice and data transmission within a range of
about 50 miles.
• Examples of MANs include local ISPs, cable
television companies, and local telephone
companies.
WAN
Wide Area Network
• A WAN covers a large geographical area and
typically consists of smaller networks, which might
use different computer platforms and network
technologies.
• Networks for nationwide banks and large retailers
are classified as WANs.
Other Types of Computer
Networks
• Intranet
• An organizations restricted computer network
• Private, yet using WWW software
• Extranet
• Part of a organization‘s intranet that is extended to users
•
outside the organization – usually via WWW.
Customer access
• VPNs
• A virtual private network (VPN) is a private, secure path
across a public network that allows authorized users
secure access to the company network.
What is the Internet?
• Internet
• A worldwide computer network using TCP/IP protocol to
transmit and exchange data.
• (TCP/IP is a set of communication protocols used by
networks.) Transmission Control Protocol/Internet
Protocol.
• The Internet is a worldwide system of computer
networks - a network of networks in which users at any
one computer can, if they have permission, get
information from any other computer.
World Wide Web
• The web consists of Web pages and documents
connected through links that include text, graphics,
sound, and video.
E-commerce
• E-commerce refers to buying and selling products
using the Internet.
Net Neutrality
• The idea that every Web site SHOULD have the
same value or priority as other Web sites. Net
neutrality supports the Internet’s core principle that
its networks should be neutral.
Computer Networks – Benefits
• Simultaneous Access
•
•
Software/Programs
Data
• Device Sharing
•
•
Printers
NAS – Network Access Storage
• Communication
•
•
Email
VOIP – Voice over internet protocol (Skype)
• Archiving
•
Backups of multiple clients by a single server
•
This is a huge benefit, saving time and effort