OSI Model Review

Lists the seven layers of the OSI model and significant aspects of each layer

OSI Model
Application Layer

  • Provides an interface between a host’s communication software and any necessary external applications.
  • Evaluates what resources are necessary and available resources for communication between two devices.
  • Synchronizes client/server applications.
  • Provides error control and data integrity between applications.
  • Provides system-independent processes to a host.

Presentation Layer

  • Presents data to the application layer.
  • Acts as a data format translator.
  • Handles the structuring of data and negotiating data transfer syntax to Layer 7.
  • Processes involved include data encryption, decryption, compression, and
  • decompression.’

Session Layer

  • Handles dialog control among devices.
  • Determines the beginning, middle, and end of a session or conversation that
  • occurs between applications (intermediary).

Transport Layer

  • Manages end-to-end connections and data delivery between two hosts.
  • Segments and reassembles data.
  • Provides transparent data transfer by hiding details of the transmission from the upper layers.

Network Layer

  • Determines best path for packet delivery across the network.
  • Determines logical addressing, which can identify the destination of a packet or datagram.
  • Uses data packets (IP, IPX) and route update packets (RIP, EIGRP, and so on).
  • Uses routed protocols IP, IPX, and AppleTalk DDP.
  • Devices include routers and Layer 3 switches.

Data Link Layer

  • Ensures reliable data transfer from the Network layer to the Physical layer.
  • Oversees physical or hardware addressing.
  • Formats packets into a frame.
  • Provides error notification.
  • Devices include bridges and Layer 2 switches.

Physical Layer

  • Moves bits between nodes.
  • Assists with the activation, maintenance, and deactivation of physical connectivity
  • between devices.
  • Devices include hubs and repeaters.

OSI Layers
OSI Model

 

OSI Model

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CCNA Exam – OSI & TCP/IP Model

Cisco CCNA Notes

 

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