INTRODUCTION TO NETWORKS

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INTRODUCTION TO NETWORKS
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What Is A Network?

• A network is a way to connect computers together
  so that they can communicate, exchange
  information, and pool resources.
• Computer networking is a combination of software,
  hardware and cables that joins computers together
  to share resource such as data, messages,
  printer, graphics, fax machines, modems and other
  devices.
• Each computer connected to the communication
  medium with a network adapter, called Network
  Interface Card.

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What Is A LAN?

• A group of computers connected together to permit
  the (rapid) transfer of information between them.
• Cheap and easy to install.
• Geographically close (easy to maintain and
  secure).
• Controlled at the Department/Group level.
• Multiple (conflicting) technologies different
  hardware, protocols, etc.
• Choice of LAN can limit supported hardware,
  operating system, and even applications.

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LAN

• There are three roles for computers in a local
  area network
• Client which use but do not provide network
  resources
• Peer which both use provide network
  resources
• Servers which provides network resources

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Client

• A client is a stand alone computer that gathers
  data from a user and prepares it for the server.
  The client accesses the shared resources provided
  by a server.

Server Types

• File Server
• Print Server
• Message Server
• Database Server

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What Is A WAN?

• Can use traditional transmission lines to form a
  coordinated system (e.g., leased phone lines).
• Effective for large transnational companies.
• WAN transmissions dont burden the local LANs
• They route through special purpose computers.
• Costs of planning, infrastructure, hardware.
• Different LAN/WAN technologies are often
  incompatible.

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LAN WAN

• LAN (Local Area Networks) users are in a
  relatively small area, such as one floor of a
  large office complex or the offices and warehouse
  of a small company.
• WANs can span cities, countries and continents by
  incorporated dedicated network devices such as
  bridges and routers, which connect LANs together
  using public communication carrier.

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Data Sharing Before Networks

• Before network were implemented, people could
  share data in three basic ways listed below
• Voice communication
• Memos
• Copying information to a physical medium and
  passes it on to another user.

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Need For Networking

• Network provides following advantages
• Allows common files to be shared from a central
  location among multiple users.
• Allows sharing of devices such as printer, faxes,
  modems and scanner etc.
• Add to the security of an organization by
  requiring users to log on.
• Allow important files to be managed and backed up
  from a central location.

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Network Benefits

• Allowing simultaneous access to critical programs
  data.
• Allowing people to share peripheral devices.
• Streamline personal communication with e-mail.
• Making backup process easier.

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Personal Communication With E-mail

• Video conferencing
• Teleconference
• Net meeting
• Exchange servers
• Collaborative software

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Data Sharing - With Networks

• Reduce computing cost by sharing data and
  peripherals such as printers.
• Reduces support cost by establishing corporate
  standards for applications.
• Centralizes the installation, management and
  upgrade of applications software.

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Data Sharing - With Networks

• Reducing computing costs by sharing data and
  peripherals such as printers.
• Increasing communication and scheduling
  capabilities.
• Accelerates access to corporate data.
• Increases security by requiring users to enter a
  user name and password to access the network.

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Network Topologies For LANs

• Bus Topology
• Star Topology
• Ring Topology

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BUS Topology
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Bus Topology - Advantages

• It requires less cabling than other topologies.
• The cabling and hardware are relatively
  inexpensive.
• It is easy to install.
• Adding additional nodes is easy.

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Bus Topology - Disadvantages

• It is difficult to troubleshoot because there is
  no central distribution point
• Bus failures (cable break or disconnections) can
  stop all communication on the bus, and locating
  the problem can be difficult.

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Star Topology
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Star Topology - Advantages

• It is easy to troubleshoot because traffic flow
  can easily be isolated from the hub.
• It is easy to configure. A computer can be added
  or removed with no effect on any other connected
  computer.

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Star Topology - Disadvantages

• It requires more cabling than other topologies.
• It is moderately difficult to install because
  each node is separately connected.
• It is crucially dependent on the hub. If the hub
  fails, the entire network cannot operate.

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Ring Topology
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Ring Topology - Advantages

• All connected computer have equal access. Each
  computer has the same opportunity to transmit.
  (Time Sharing)
• As more computers are added to the network,
  performance does not suffer appreciably because
  each computer accesses the media in sequential
  order

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Ring Topology - Disadvantages

• Media failure can stop all communication.
• It is difficult to troubleshoot a Ring network.
• Adding or Removing computers disrupts the
  network.