Open Systems Interconnection OSI

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Open Systems Interconnection (OSI)

• Supplemental Material

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Internetworking
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Open Systems Interconnection (OSI)

• Developed by the International Organization for
  Standardization (ISO) in 1984
• The primary architectural model for intercomputer
  communications.
• A conceptual model composed of seven layers, each
  specifying particular network functions.
• Describes how information from a software
  application in one computer moves through a
  network medium to a software application in
  another computer.

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OSI Model
F-Ds Model
Internet Model
OSI Model
Application layer http, telnet, snmp, smtp,
nfs, ftp
Application layer
TCP, UDP
Network layer
IPv4, IPv6
Data Link layer
Data Link Layer
(HDLC)
Physical layer
Physical layer
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OSI Model

• Network layer
• provides routing and related functions
• Transport layer
• implements reliable internetwork data transport
  services
• Session layer
• establishes, manages and terminates communication
  sessions between presentation layer entities
• Presentation layer
• provides a variety of coding and conversion
  functions
• Application layer
• closest to the end user

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Protocols

• Protocols fall into one of the following groups
• LAN protocols
• WAN protocols
• Network protocols
• Routing protocols

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Interaction between Layers
A data link layer contact three other layers
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Headers and Data
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Physical-layer Implementation
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OSI Data Link Layer
IEEE has subdivided data link layer into two
sub-layers.