OSI Model Review

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

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.

Download OSI Download Model Chart

CCNA Exam – OSI & TCP/IP Model

Cisco CCNA Notes