Chapter 2: Networking Standards and the OSI Model

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Chapter 2 Networking Standards and the OSI
Model
Network Guide to Networks
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Networking Standards Organizations

• Standards are documented agreements containing
  technical specifications
• ANSI (American National Standards Institute) is
  an organization composed of more than a thousand
  representatives from industry and government who
  together determine standards for the electronics
  industry and other fields, such as chemical and
  nuclear engineering, health and safety, and
  construction

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Networking Standards Organizations (continued)

• ANSI also represents the United States in setting
  international standards
• EIA (Electronic Industries Alliance) is a trade
  organization composed of representatives from
  electronics manufacturing firms across the United
  States

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Networking Standards Organizations (continued)

• TIA (Telecommunications Industry Association)
  Focuses on standards for information technology,
  wireless, satellite, fiber optics, and telephone
  equipment
• TIA/EIA alliance are its guidelines for how
  network cable should be installed in commercial
  buildings, known as the TIA/EIA 568-B Series.

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Networking Standards Organizations (continued)

• IEEE (Institute of Electrical and Electronics
  Engineers), or I-triple-E, is an international
  society composed of engineering professionals
• IEEE goals are to promote development and
  education in the electrical engineering and
  computer science fields

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Networking Standards Organizations (continued)

• ISO (International Organization for
  Standardization), headquartered in Geneva,
  Switzerland, is a collection of standards and
  organizations representing 148 countries
• ISOs goal is to establish international
  technological standards to facilitate global
  exchange of information and barrier-free trade

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Networking Standards Organizations (continued)

• The ITU (International Telecommunication Union)
  is a specialized United Nations agency that
  regulates international telecommunications,
  including radio and TV frequencies, satellite and
  telephony specifications, networking
  infrastructure, and tariffs applied to global
  communications

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Networking Standards Organizations (continued)

• ISOC (Internet Society), founded in 1992, is a
  professional membership society that helps to
  establish technical standards for the Internet
• ISOC oversees groups with specific missions, such
  as the IAB and IETF

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Networking Standards Organizations (continued)

• IAB (Internet Architecture Board) is a technical
  advisory group of researchers and technical
  professionals interested in overseeing the
  Internets design and management
• IETF (Internet Engineering Task Force), the
  organization that sets standards for how systems
  communicate over the Internetin particular, how
  protocols operate and interact

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Networking Standards Organizations (continued)

• IANA and ICANN
• Every computer / host on a network must have a
  unique address
• Internet Assigned Numbers Authority (IANA) kept
  records of available and reserved IP addresses
  and determined how addresses were issued out
• Internet Corporation for Assigned Names and
  Numbers (ICANN), a private, nonprofit corporation
  and is now ultimately responsible for IP
  addressing and domain name management

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The OSI Model

• In the early 1980s, ISO began work on a universal
  set of specifications that would enable computer
  platforms across the world to communicate openly
• This model, called the Open Systems
  Interconnection (OSI) Model, divides network
  communications into seven layers

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The OSI Model (continued)
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The OSI Model (continued)

• Application Layer
• Separates data into protocol data units (PDUs)
• Application layer PDUs progress down through OSI
  Model layers 6, 5, 4, 3, 2, and 1
• Data traverses the network until it reaches the
  second computers Physical layer
• Transfer of information happens in milliseconds

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The OSI Model (continued)
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The OSI Model (continued)

• Application Layer
• Does not include software applications, such as
  Microsoft Word or Netscape
• Services communicate between software programs
  and lower-layer network services
• File, print, message, database, and application
  services

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The OSI Model (continued)

• Application Layer
• World Wide Web (WWW)
• Email - SMTP (Simple Mail Transport Protocol or
  the X.400)

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The OSI Model (continued)
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The OSI Model (continued)
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The OSI Model (continued)

• Presentation Layer
• Protocols at the Presentation layer accept
  Application layer data and format it
• Serves as a translator and are the standards
  which are involved in multimedia
• Presentation layer protocols perform the coding,
  compression and also manage data encryption and
  decryption

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The OSI Model (continued)

• Session Layer
• Protocols in the Session layer coordinate and
  maintain communications between two nodes
• Session refers to a connection for ongoing data
  exchange between two parties

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The OSI Model (continued)

• Session Layer (continued)
• Session layers functions are establishing and
  keeping alive the communications link for the
  duration of the session
• Keep the communication secure
• Synchronizing the dialog between the two nodes
• Determining whether communications have been cut
  off, and, if so, figuring out where to restart
  transmission and terminating communications

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The OSI Model (continued)

• Transport Layer
• Protocols in the Transport layer accept data from
  the Session layer and manage end to-end delivery
• Ensures that the data is transferred from point A
  to point B reliably, in the correct sequence, and
  without errors

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The OSI Model (continued)

• Transport Layer (continued)
• Without Transport layer services, data could not
  be verified or interpreted by its recipient
• Handles flow control
• Some Transport layer protocols take steps to
  ensure that data arrives exactly as it was sent.

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The OSI Model (continued)

• Transport Layer (continued)
• Such protocols are known as connection-oriented,
• TCP is one example of a connection-oriented
  protocol
• Three Step Process
• Request (Client sends)
• Acknowledgment (ACK)
• Client Acknowledgement (ACK)

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The OSI Model (continued)

• Transport Layer (continued)
• Checksum method of error checking
• Connectionless protocols
• Process is known as segmentation
• Necessary for data units to match a networks
  maximum transmission unit (MTU)

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The OSI Model (continued)

• Transport Layer (continued)
• Reassembly
• Sequencing
• Identifying segments that belong to the same
  group

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The OSI Model (continued)
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The OSI Model (continued)
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The OSI Model (continued)

• Network Layer
• Primary function of protocols at the Network
  layer
• Translate network addresses
• Decide how to route data
• Network layer addresses
• Also called logical addresses or virtual
  addresses

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The OSI Model (continued)

• Network Layer (continued)
• Routers belong in the Network layer
• Perform Fragmentation

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The OSI Model (continued)
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The OSI Model (continued)

• Data Link Layer
• Primary function of protocols is to divide data
  into distinct frames that can then be transmitted
  by the Physical layer
• IEEE has divided the Data Link layer into two
  sublayers
• Logical Link Control (LLC)
• Media Access Control (MAC)

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The OSI Model (continued)
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The OSI Model (continued)

• Physical Layer
• Lowest, or first, layer of the OSI Model
• Protocols at the Physical layer
• Accept frames from the Data Link layer
• Generate voltage so as to transmit signals
• Receiving data detect voltage and accept signals
• Pass on to the Data Link layer

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Applying The OSI Model
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Applying The OSI Model (continued)

• Communication Between Two Systems
• At each layer of the OSI Model, some information
  is added to the original data

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Applying The OSI Model (continued)
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Applying The OSI Model (continued)

• Frame Specifications
• Two major categories of frame types
• Ethernet
• developed at Xerox in the early 1970s
• Token Ring
• developed by IBM in the 1980s

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IEEE Networking Specifications

• Project 802
• Effort to standardize physical and logical
  elements of a network
• Frame types and addressing
• Connectivity,
• Networking media,
• Error checking algorithms,
• Encryption,

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IEEE Networking Specifications (continued)

• Project 802 (continued)
• Emerging technologies,
• And more
• Can be applied to the layers of the OSI Model

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IEEE Networking Specifications (continued)
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Chapter Summary

• Standards are documented agreements containing
  precise criteria
• Significant standards organizations
• ANSI, EIA/TIA, IEEE, ISO, ITU, ISOC, IANA, and
  ICANN

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Chapter Summary (continued)

• Excellent model for understanding communications
• Protocols in the Application layer, the seventh
  layer of the OSI Model, enable software programs
  to negotiate

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Chapter Summary (continued)

• Protocols in the Presentation layer, the sixth
  OSI Model layer, serve as translators between the
  application and the network

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Chapter Summary (continued)

• Protocols in the Session layer, the fifth OSI
  Model layer,
• coordinate and maintain links between two devices
  
• synchronize dialog
• Primary function of protocols in the Transport
  layer, the fourth OSI Model layer, is to oversee
  end-to-end data delivery

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Chapter Summary (continued)

• Protocols in the Network layer, the third OSI
  Model layer, manage logical addressing and
  determine routes

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Chapter Summary (continued)

• Network layer addresses, also called logical or
  virtual addresses, are assigned to devices
  through operating system software
• Primary function of protocols at the Data Link
  layer, the second layer of the OSI Model, is to
  organize data they receive from the Network layer
  into frames

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Chapter Summary (continued)

• Data Link layer is subdivided into the Logical
  Link Control and MAC sublayers
• LLC sublayer ensures a common interface
• MAC sublayer is responsible for adding physical
  address data to frames
• Protocols at the Physical layer generate and
  detect voltage

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Chapter Summary (continued)

• Protocols at the Physical layer generate and
  detect voltage

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Chapter Summary (continued)

• Data request from a software program is received
  by the Application layer protocols and is
  transferred down through the layers of the OSI
  Model until it reaches the Physical layer
• Data frames are small blocks of data with
  control, addressing, and handling information
  attached to them

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Chapter Summary (continued)

• Data request from a software program is received
  by the Application layer protocols and is
  transferred down through the layers of the OSI
  Model until it reaches the Physical layer
• Data frames are small blocks of data with
  control, addressing, and handling information
  attached to them

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Chapter Summary (continued)

• In addition to frame types and addressing
  schemes, the IEEE Networking Specifications apply
  to connectivity, networking media, error checking
  algorithms, encryption, emerging technologies,
  and more
• Significant 802 standards are 802.3, which
  describes Ethernet 802.5, which describes Token
  Ring and 802.11, which describes wireless
  networking