An Introduction to Computer Networking

1
An Introduction to Computer Networking
2
Objectives

• Identify elements of a network
• Describe several specific uses of a network
• Distinguish between client/server and
  peer-to-peer networks

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Networks and Standalone Computers

• Network
• Group of computers and other devices connected by
  some type of transmission media
• Networks enable users to share devices and data,
  collectively called a networks resources
• Standalone computer
• Uses programs and data only from its local disks
  and is not connected to a network

4
Local and Remote Computers

• Local computer
• Computer on which user is working
• Remote computer
• Computer that user controls or works on via
  network connection

5
Peer-to-Peer Network

• Computers communicate on single segment of cable
  and share each others data and devices
• Simple example of a local area network (LAN)

Simple peer-to-peer network
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Local Area Network (LAN)

• Network of computers and other devices confined
  to relatively small space
• LANs involving many computers are usually
  server-based
• On a server-based network, special computers
  (known as servers) process data for and
  facilitate communication between other computers
  on the network (known as clients)

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Networking Basics

• Workstation
• Computer that typically runs a desktop operating
  system and connects to a network
• Client/server architecture
• Networking model in which clients use central
  server to share applications, devices, and data

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Networking Basics

• Client/server network
• Network based on client/server architecture
• Network operating system
• Special software designed to manage data and
  other resources on a server for a number of
  clients

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Networking Basics
LAN with a file server
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Advantages of Server-Based over Peer-to-Peer
Networks

• User login accounts and passwords can be assigned
  in one place
• Access to multiple shared resources can be
  centrally granted
• Servers are optimized to handle heavy processing
  loads and dedicated to handling requests from
  clients
• Servers can connect more than a handful of
  computers

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MANs and WANs

• Metropolitan area network (MAN)
• Network connecting clients and servers in
  multiple buildings within limited geographic area
• Wide area network (WAN)
• Network that spans large distance and connects
  two or more LANs
• The Internet is an example of a very intricate
  and extensive WAN that spans the globe

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WAN
A simple WAN
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Elements Common to AllServer-Based Networks

• Client
• In addition to referring to a computer on the
  network, may also refers to human user of client
  workstation
• Server
• Workstation
• Network interface card (NIC)
• Enables workstation to connect to the network and
  communicate with other computers

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Elements Common to AllServer-Based Networks

• Network operating system (NOS)
• Host
• Server that manages shared resources
• Node
• Client, server, or other device that can
  communicate over a network and that is identified
  by a unique identifying number, known as its
  network address

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Elements Common to AllServer-Based Networks

• Topology It is the physical layout of computer
  network

• Commonly used network topologies are

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Elements Common to AllServer-Based Networks

• Protocol
• Rules network uses to transfer data
• Data Packets
• The distinct units of data transmitted from one
  computer to another on a network
• Addressing
• Scheme for assigning unique identifying number to
  every workstation on network
• The number that uniquely identifies each
  workstation and device on a network is its address

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Elements Common to AllServer-Based Networks

• Transmission media
• Means through which data are transmitted and
  received

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How Networks Are Used

• Services
• Features provided by a network
• File and print services
• Communications services
• Mail services
• Internet services
• Management services

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Network Services

• File services
• Refers to capability of a server to share data
  files, applications, and disk storage space
• Server that provides file services is called a
  file server
• Print services
• Allows printers to be shared by several users on
  a network

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Network Services

• Communications services
• Allow remote users to connect to a network
• Remote user
• Person working on a computer in a different
  geographical location from the LANs server
• Communications server
• Server that runs communications services
• Also referred to as access servers and remote
  access servers

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Network Services

• Mail services
• Coordinate storage and transfer of e-mail between
  users on a network
• Gateway
• Combination of software and hardware enabling two
  different kinds of networks to exchange data
• Internet services
• Enable networks to communicate with the Internet

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Network Services

• Management services
• Centrally administer and simplify complicated
  management tasks on the network
• Numerous services fall under category of network
  management

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Important Management Services

• Traffic monitoring and control
• Traffic
• Data transmission and processing activity taking
  place on a computer network at any given time
• Segment
• Part of LAN that is logically separated from
  other parts of LAN and that shares fixed amount
  of traffic capacity

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Important Management Services

• Load balancing
• Distributing process activity evenly across a
  network so that no single device is overwhelmed
• Hardware diagnosis and failure alert
• Determining when a network component fails and
  automatically notifying network administrators
  through e-mail or pager

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Important Management Services

• Asset management
• Collecting and storing data on number and types
  of software and hardware assets in an
  organizations network
• License tracking
• Determining how many copies of a single
  application are currently in use on a network

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Important Management Services

• Security auditing
• Evaluating what security measures are currently
  in force and notifying network administrator if a
  security breach occurs
• Software distribution
• Automatically transferring data file or program
  from the server to a client on the network

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Important Management Services

• Address management
• Centrally administering a finite number of
  network addresses for an entire LAN
• Backup and restoration of data
• Backing up
• Copying critical files to a secure storage area
• Restoring
• Retrieving data if original files are lost or
  deleted