introduction to basicComputer Networks .pptx

 A computer data network is a collection of hosts connected by networking devices such
as computers, printers, scanners, smartphones, and file and print servers.
 Resources shared across networks include different types of services, storage devices,
and applications.
 Network devices link together using a variety of connections:
•Copper cabling
•Fiber-optic cabling
•Wireless connection
 Benefits from networking include:
•Fewer peripherals needed
•Increased communication capabilities
•Avoid file duplication and corruption
•Lower cost licensing
•Centralized administration
•Conservation of resources
Computer Networks

 We live in a world we barely imagined 20 years ago.
 What wouldn’t we have without the Internet?
 What will be possible in the future using the network as the platform?
Technology Then and Now

 Advancements in networking technologies are helping create a world without boundaries.
 The immediate nature of communications over the Internet encourages global communities.
 Cisco refers to the impact of the Internet and networks on people the “human network”.
Networking Today
No Boundaries

 Do you remember sitting in a classroom, like this?
 You don't have to be in school anymore to take a class. You don't have to be in a classroom to have
a teacher.
Networking Today
Networks Support the Way We Learn

Networking Today
Networks Support the Way We Work
 The globalization of the Internet
has empowered individuals to
create information that can be
accessed globally.
 Forms of communication:
 Texting
 Social Media
 Collaboration Tools
 Blogs
 Wikis
 Podcasting

Networks Support the Way We Work
 Data networks have evolved into
helping support the way we work.
 Online learning opportunities
decrease costly and time-consuming
travel.
 Employee training is becoming more
cost effective.

Network Components
Overview of Network Components
 A network can be as simple as a single
cable connecting two computers or as
complex as a collection of networks that
span the globe.
 Network infrastructure contains three broad
categories of network components:
 Devices
 Media
 Services

Network Components
 End Devices
 An end device is where a
message originates from or
where it is received.
 Data originates with an end
device, flows through the
network, and arrives at an
end device

Network Components
Intermediary Network Devices
 An intermediary device interconnects end devices in a network. Examples include:
switches, wireless access points, routers, and firewalls.
 The management of data as it flows through a network is also the role of an intermediary
device including:
 Regenerate and retransmit data signals.
 Maintain information about what pathways exist through the network and internetwork.
 Notify other devices of errors and communication failures.

Network Media
 Communication across a network is
carried through a medium which allows
a message to travel from source to
destination.
 Networks typically use three types of
media:
 Metallic wires within cables, such as
copper
 Glass, such as fiber optic cables
 Wireless transmission

Network Representations
 Network diagrams, often called topology
diagrams, use symbols to represent devices
within the network.
 In addition to the device representations
on the right, it is important to remember
and understand the following terms:
 Network Interface Card (NIC)
 Physical Port
 Interface

Physical Network Components
A Modem is an electronic device that connects to the Internet via an ISP.
 A modem converts digital data to analog signals for transmission over a
phone line.
 Internal modems plug into an expansion slot on the motherboard.
 External modems connect to a computer through the serial and USB ports.

Physical Network Components
 Network devices:
•Computers
•Hubs
•Switches
•Routers
•Wireless access points
 Network media:
•Twisted-pair copper cabling
•Fiber-optic cabling
•Radio waves

Network Devices
 VoIP phones - carry telephone calls over the data networks and Internet.
 Hardware firewalls - use various techniques for determining what is permitted or denied access to a
network segment.
 Internet appliance – web TV, game consoles, Blu-ray players etc.
 Purchasing Authentic Networking Devices - Computer and network problems can be related to
counterfeit components.
Network-attached storage (NAS)
 Consists of one or more hard drives, an Ethernet connection, and an embedded operating system

Types of Networks
 Two most common types of networks:
 Local Area Network (LAN) – spans a
small geographic area owned or
operated by an individual or IT
department.
 Wide Area Network (WAN) – spans a
large geographic area typically
involving a telecommunications service
provider.
 Other types of networks:
 Metropolitan Area Network (MAN)
 Wireless LAN (WLAN)
 Storage Area Network (SAN)

Local Area Networks
 Three characteristics of LANs:
 Spans a small geographic area
such as a home, school, office
building, or campus.
 Usually administered by a single
organization or individual.
 Provides high speed bandwidth
to end and intermediary devices
within the network.

Wide Area Networks
 Three characteristics of WANs:
 WANs interconnect LANs over wide geographical areas such as between cities, states, or countries.
 Usually administered by multiple service providers.
 WANs typically provide slower speed links between LANs.

The Internet
 The Internet is a worldwide collection of
interconnected LANs and WANs.
 LANs are connected to each other
using WANs.
 WANs are then connected to each
other using copper wires, fiber optic
cables, and wireless transmissions.
 The Internet is not owned by any
individual or group, however, the
following groups were developed to
help maintain structure:
 IETF
 ICANN
 IAB

Network Devices
 Hub
• Extend the range of a signal by receiving then regenerating it and sending it out all
other ports.
• Allow for collisions on the network segment and are often not a good solution.
• Also called concentrators because they serve as a central connection point for a LAN.
 Bridges and Switches
• A bridge has the intelligence to determine if an incoming frame is to be sent to a
different segment, or dropped. A bridge has two ports.
• A switch (multiport bridge) has several ports and refers to a
table of MAC addresses to determine which port to use to forward the frame.
• Power over Ethernet (PoE)
• PoE switch transfers small amounts of DC current over Ethernet cable, along with
data, to power PoE devices such as Wi-Fi access points.

Network Devices (Continued)
 Routers
• Devices that connect entire networks to each other. They use IP addresses to forward packets to other
networks.
• A router can be a computer with special network software installed or can be a device built by network
equipment manufacturers.
• Routers contain tables of IP addresses along with optimal routes to other networks.
 Wireless Access Points (WAP)
• Provide network access to wireless devices such as laptops and PDAs.
• Use radio waves to communicate with radios in computers, PDAs, and other wireless access points.
• Have limited range of coverage.
 Multipurpose Devices
• Perform more than one function.
• More convenient to purchase and configure just one device.
• Combines the functions of a switch, a router and a wireless access point into one device.
• The Linksys E2500 is an example of a multipurpose device.

Twisted-Pair Cabling
 A pair of twisted wires forms a circuit that transmits data.
 The twisted wires provide protection against crosstalk (electrical noise) because of the
cancellation effect.
 Pairs of copper wires are encased in color-coded plastic insulation and twisted together.
 An outer jacket of poly-vinyl chloride (PVC)
protects the bundles of twisted pairs.
 There are two types of this cable:
• Unshielded twisted-pair (UTP)
(Cat 3, Cat 5, 5e ,Cat 6 and Cat 7)
• Shielded twisted-pair (STP)

Fiber-Optic Cable
 A glass or plastic strand that transmits
information using light and is made up
of one or more optical fibers enclosed
together in a sheath or jacket.
 Not affected by electromagnetic or
radio frequency interference.
 Signals are clearer, can go farther,
and have greater bandwidth than
with copper cable.
 Usually more expensive than copper
cabling and the connectors are more
costly and harder to assemble.
 Two types of glass fiber-optic cable:
Multimode and Single-mode

Topology Diagrams
 Note the key differences between the two topology diagrams (physical location of devices vs.
ports and network addressing schemes)

LAN Physical Topologies
 A physical topology defines the way in which computers, printers, and other devices
are connected to a network.
 Bus
• Each computer connects to a common cable The ends of the cable have a terminator
installed to prevent signal reflections and network errors.
• Only one computer can transmit data at a time or frames will collide and be destroyed.
 Ring
• Hosts are connected in a physical ring or circle.
• A special frame, a token, travels around the ring, stopping at each host to allow data
transmission.
• There are two types of ring topologies:
• Single-ring and Dual-ring

LAN Physical Topologies (Continued)
 Star
• Has a central connection point : a hub, switch, or router.
• Easy to troubleshoot, since each host is connected to the central device with its own wire.
 Hierarchical or Extended Star Topology
• A star network with an additional networking device connected to the main networking
device to increase the size of the network.
• Used for larger networks.
 Mesh Topology
• Connects all devices to each other.
• Used in WANs that interconnect LANs. The Internet is an example of a mesh topology.
 Hybrid
• A hybrid topology is a combination of two or more basic network topologies, such as a star-
bus, or star-ring topology. The advantage of a hybrid topology is that it can be implemented
for a number of different network environments

Peer-to-Peer
 Client and server software usually run on separate computers.
 However, in small businesses or homes, it is typical for a client to also function as the
server. These networks are called peer-to-peer networks.
 Peer-to-peer networking advantages: easy to set up, less complex, and lower cost.
 Disadvantages: no centralized administration, not as secure, not scalable, and
slower performance.

Clients and Servers
 Every computer connected to a
network is called a host or end
device.
 Servers are computers that provide
information to end devices on the
network. For example, email servers,
web servers, or file server
 Clients are computers that send requests
to the servers to retrieve information
such as a web page from a web server
or email from an email server.

introduction to basicComputer Networks .pptx

introduction to basicComputer Networks .pptx

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