ISO and OSI Network Model


ISO and OSI Network Model NOTES

ISO and OSI Model:

  • ISO Developed a standard for data communication called Open System Interconnection.
  • OSI has seven layers.
  1. o  Physical Layer
  2. o  Data Link Layer
  3. o  Network Layer
  4. o  Transport Layer
  5. o  Session Layer
  6. o  Presentation Layer
  7. o  Application Layer

Physical Layer:

  • This layer deals with system of bits.
  • Collect data from upper layer and send it to required computer in the form of bits.
  • RS-232 connector is used for data transmission.

Data Link Layer:

  • Responsible for node-to-node delivery of message.
  • Control the rate of flow of data.

Network Layer:

  • It decides which path of data should send from one node to other.
  • Switches, Routers and NIC Cards (Network interface card) decides the routing based on network conditions, priority of service and other factors.
  • TCP/IP is very important protocol of this layer.

Transport Layer:

  • Responsible for end-to-end delivery of entire message.
  • If the link goes down then this layer send data into other link (Path).
  • Arrangement of data in its order.
  • Remove errors.
  • Control rate of flow of data.

Session Layer:

  • Establish a connection between two-application across network.
  • Its function is performing
  1. o  Security
  2. o  Logging
  3. o  Administration

Presentation Layer:

  • This layer represents data in user understandable form.
  • Techniques used are
  1. o  Translation
  2. o  Encryption
  3. o  Compression

Application Layer:

  • This layer serves the user.
  • User can control it directly.
  • It includes services such as o E-mail
  1. o  File sharing
  2. o  File printing and other software


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