Lesson 3-Communicating Over Networks

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Lesson 3-Communicating Over Networks
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Overview

• Understand network communication.
• Decipher computer addressing.
• Network communication protocols.
• Network designing.

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Understand Network Communication

• A sender, a receiver, a message, and a medium are
  required for network communication.
• In order to communicate effectively, it is
  essential that the systems on a network use the
  same language.

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Understand Network Communication

• Computer signals
• Messages

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Computer Signals

• Digital signal and analog signal are the two
  forms in which computer signals are transmitted.
• When two computers communicate on a network, they
  exchange digital signals.
• Each signal or digit is represented by a distinct
  state.

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Computer Signals
An analog signal
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Computer Signals

• The presence of an electrical signal is
  considered as on, and is represented by the
  digit one.
• The absence of an electrical signal is considered
  as off, and is represented by a zero.
• A system that uses zeros and ones is called a
  binary system.

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Computer Signals

• A modem is required to convert a digital signal
  into an analog signal, and vice versa.
• The process of converting digital signals into
  analog signals is called modulation.
• The process of converting analog signals back
  into digital signals is called demodulation.

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Computer Signals

• Bits
• The term bit is used to represent a single
  instance of a digital signal.
• These can also be represented by other medium
  states, such as the relative signal strengths of
  light pulses or radio waves.
• A bit becomes important when it is combined with
  other bits to create different characters.

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Computer Signals

• Bytes
• Eight bits make a byte.
• A byte can be used to represent up to 256
  characters, digits, or symbols on a computer.

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Messages

• When a computer communicates with itself or with
  other computers, it assembles the characters into
  meaningful data.
• The data can then be easily received and
  interpreted by the receiving computer.

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Decipher Computer Addressing

• Unique address.
• Physical address.
• Hexadecimal notation.
• Node address.
• Network addresses and their implementation.

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Unique Address

• A unique address with an exact name and storage
  path is required for storing and retrieving data
  accurately over a network.
• Network addressing is handled by ensuring that
  each address is unique.

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Physical Address

• The physical address is the first element of a
  computers network address.
• It is a special serial number assigned to a
  component installed inside the computer.
• The numbers are controlled by the networking
  industrys regulating organization, the Institute
  of Electrical and Electronics Engineers (IEEE).

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Physical Address

• The equipment manufacturer requests a block of
  unique 48-bit binary numbers and assigns a
  separate number to each network interface card
  (NIC) that they create.
• The first 24 bits of the MAC address assigned to
  a NIC are set by the IEEE to identify the
  manufacturer.
• The second 24 bits are used for a unique serial
  number that is assigned to the individual network
  interface card by its manufacturer.

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Physical Address

• The physical address, also know as the Media
  Access Control (MAC) address, is a means by which
  the computer gains access to the networking
  medium.
• The physical (or MAC) address is also sometimes
  referred to as the hardware address.

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Hexadecimal Notation

• Hexadecimal notation (hex) is a numbering system
  that uses 16 alphanumeric characters instead of
  the usual ten numeric digits.
• Hex is a shorthand for writing binary numbers.
• A single hex digit is used to represent four
  digits of a binary number.

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Node Address

• A unique node address is required for every
  computer on a network.
• Adding node numbers to the MAC helps locate the
  randomly generated node numbers.
• Each node address is useful within the specific
  network to which it is attached.

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Network Addresses and Their Implementation

• The network address is a combination of the node
  address and the MAC address.
• The source address and the destination address
  are required to transmit data effectively.
• The source address specifies where the
  transmitted information originates.

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Network Addresses and Their Implementation

• The destination address specifies the
  informations destination.
• Both the source and destination addresses are
  then added to the data being transmitted to make
  sure that the message is routed properly.

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Network Addresses and Their Implementation
Directing messages to the specific computer
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Network Communication Protocols

• Network communication decisions.
• Layered communication.
• Internet communication.
• Intranet/Extranet communication.

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Network Communication Decisions

• Language
• A set of language rules developed to effectively
  communicate over a network is called a protocol.
• NetBIOS (Network Basic Input/Output System) and
  NetBEUI (NetBIOS Extended User Interface) were
  two networking languages used earlier.

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Network Communication Decisions

• Broadcasting versus routing
• Broadcasting involves passing digital messages
  over the network medium.
• Routing involves deciding the recipient of the
  message and sending it to them directly.

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Network Communication Decisions

• Message format - Formatting refers to combining
  mutually acceptable characters in such a way that
  messages can be exchanged.

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Layered Communication

• The International Standards Organization (ISO)
  suggested the use of the Open Systems
  Interconnection (ISO) model to explain network
  communication.
• The OSI models standards are open and made
  available to everyone to enable interconnectivity
  of different systems.
• The model simplifies complex networking
  activities by grouping the steps into seven
  layers.

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Layered Communication
Layers in the OSI Model
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Layered Communication
Layers in the OSI Model
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Internet Communication

• Transmission Control Protocol/Internet Protocol
  (TCP/IP).
• User Datagram Protocol (UDP).
• Domain Name Service (DNS).
• File Transfer Protocol (FTP).
• Simple Mail Transfer Protocol (SMTP).

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Transmission Control Protocol/Internet Protocol
(TCP/IP)

• TCP/IP is the most widely used protocol, and acts
  as the Transport/Network layer protocol.
• The TCP makes sure that the data is correctly
  sized, properly put in packets, and sequenced
  back in the right order upon receipt.
• The TCP, also known as a connection-oriented
  protocol, links the Application layer to the
  Network layer.

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Transmission Control Protocol/Internet Protocol
(TCP/IP)

• The IP is a set of rules that is concerned with
  sending a message to the correct address and is,
  therefore, called a connectionless protocol.
• The IP is also responsible for the creation and
  maintenance of an addressing scheme, known as the
  IP address.
• IP operates at the Network layer.

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Transmission Control Protocol/Internet Protocol
(TCP/IP)

• Each IP address is a unique 4-byte (or 32-bit)
  number, and each byte is separated by a decimal
  point.
• IP addresses can be used as static assignments to
  individual computers, or can be assigned
  dynamically.

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Transmission Control Protocol/Internet Protocol
(TCP/IP)

• The Dynamic Host Configuration Protocol (DHCP) is
  used to assign IP addresses dynamically.
• The DHCP is a set of rules that allow a group of
  computers to effectively lease IP numbers to
  network members when required.

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User Datagram Protocol (UDP)

• UDP is a connectionless protocol that operates at
  the Transport layer.
• This protocol does not have to open a connection
  with the receiver and it does not have to carry
  out any error correction.
• UDP does not perform any checks to ensure the
  receipt of data, so it never carries out
  automatic retransmissions.

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Domain Name Service (DNS)

• The DNS is used for locating resources on the
  Internet.
• It operates at the Application layer.
• The DNS server uses the IP address to link to the
  Uniform Resource Locator (URL) concerned.
• Examples of domain names include com, net, org,
  edu, gov, and mil.

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File Transfer Protocol (FTP)

• The FTP is used for transferring files over the
  Internet.
• It operates using a client at the Application
  layer and a server at the opposite end.

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File Transfer Protocol (FTP)

• It is also possible to send files to an FTP site,
  making the process of exchanging large pieces of
  information fast and simple.
• Some FTP servers allow anonymous logins, while
  others require passwords and proper
  authentication.

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Simple Mail Transfer Protocol(SMTP)

• SMTP is a set of rules that regulates the
  transfer of e-mail over the Internet.
• The Post Office Protocol (POP) or the Internet
  Message Access Protocol (IMAP) is required to
  read e-mail.

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Simple Mail Transfer Protocol(SMTP)

• Graphic or document attachments are handled by an
  SMTP extension called Multipurpose Internet Mail
  Extensions (MIME).
• The MIME converts each attachment into a coded
  form, similar to text, for transfer over SMTP.

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Intranet/Extranet Communication

• Intranet communication refers to using Internet
  communication techniques without using an
  Internet connection.
• When two or more Intranets are networked without
  being connected to the Internet, it is called an
  Extranet.

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Network Designing

• Network needs.
• Network choices.
• Network layout.

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Network Needs

• Administering a network involves
• Ensuring that the systems are up and running at
  any given point in time, while making them easy
  for a user to operate.
• Maintaining the systems operation with the
  minimum amount of downtime.

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Network Choices

• Network budget The total cost of the network
  must be less than the projected earnings to
  impose an economic limit for installing and
  maintaining a network.
• Network security The required security must be
  essentially added to the network to avoid any
  kind of security issues.

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Network Choices

• The following aspects must be considered while
  choosing a networks users
• The networks users should be trained and be
  capable of handling the system.
• The number of users who would be accessing the
  system should be defined at a given point in time.

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Network Choices

• The following aspects must be considered while
  choosing a networks users (continued)
• It must be ensured that when the network access
  is at its peak, the users are able to obtain the
  services immediately after logging in.
• The maximum capacity of the network should be
  designed to handle a users request.

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Network Choices

• Network application
• It is essential to know how and why the network
  would be used.
• These facts help determine the means for
  producing the networks output and the tools that
  go into producing it.

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Network Choices

• Network growth
• Any system should allow for future growth, and
  should include added capacity for incorporating
  new resources into the network.
• Allowances should also be provided for
  technological advances.

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Network Layout

• The physical layout or the geometric pattern
  formed by the arrangement of interconnected
  computers is referred to as topology.
• Bus, ring, and star are the three most common
  types of physical topologies.

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Network Layout
Bus topology
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Network Layout
Ring topology
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Network Layout
Star topology
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Summary

• Communication involves a sender, a receiver, a
  message, and a medium.
• A bit is a single digit and a byte is made up of
  eight bits.
• A system that uses only zeros and ones is called
  a binary system.
• A modem is required to convert digital
  information into analog, and vice versa.

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Summary

• The ISO recommends the use of the OSI model to
  connect dissimilar networking components.
• The needs of all the networked resources should
  be adequately considered while panning the
  network.
• Topology refers to the physical layout or
  arrangement of computers in a network.
• The three most common topologies are bus, ring,
  and star.