OSI Model Flashcards
Layer 1
Physical
Layer 2
Data Link
Layer 3
Network
Layer 4
Transport
Layer 5
Session
Layer 6
Presentation
Layer 7
Application
Why is the OSI Model important?
Standardization:
Provides a universal framework for understanding and developing network protocols.
Interoperability:
Ensures that different hardware and software systems can communicate effectively.
Troubleshooting:
Helps network engineers isolate and resolve issues by focusing on specific layers.
Modularity:
Changes in one layer do not affect others, making it easier to update and improve protocols.
Purpose of Physical Layer
Physical connection between devices and the transmission of raw binary data (0s and 1s) over a physical medium.
Purpose of Data Link Layer
Provides reliable transmission of data across a physical network link by detecting and possibly correcting errors.
Purpose of Network Layer
Handles the routing and forwarding of data between devices across different networks.
Purpose of Transport Layer
Ensures reliable data delivery between devices, including error recovery and flow control.
Purpose of Session Layer
Manages and controls the establishment, maintenance, and termination of communication sessions between devices.
Purpose of Presentation Layer
Translates and formats data to ensure it can be understood by the application layer and by the receiving device.
Purpose of Application Layer
Provides network services to end users and interfaces with applications. It’s the layer users interact with directly.
What are the functions of the Physical Layer?
Converts digital data into electrical, optical, or radio signals for transmission.
Defines cables, connectors, voltages, frequencies, and data rates.
What are the functions of the Data Link Layer?
Organizes data into frames for transmission.
Handles MAC (Media Access Control) addresses to identify devices on the same network.
Ensures error-free delivery using checksums and acknowledgments.
What are the functions of the Network Layer?
Divides data into packets.
Determines the best path for data to reach its destination (routing).
Uses IP addresses for addressing and delivery.
What are the functions of the Transport Layer?
Divides data into segments for transmission.
Provides error detection and correction.
Ensures complete and ordered delivery of data using retransmissions when necessary.
Protocols:
TCP (Transmission Control Protocol): Reliable, connection-oriented.
UDP (User Datagram Protocol): Unreliable, connectionless, faster.
What are the functions of the Session Layer?
Synchronizes communication by establishing, maintaining, and ending sessions.
Coordinates dialog control (full-duplex, half-duplex).
What are the functions of the Presentation Layer?
Handles data encryption, decryption, compression, and conversion.
Ensures compatibility between systems with different data formats.
What are the functions of the Application Layer?
Handles application-level protocols for specific services.
Facilitates file transfers, email, and web browsing.
Examples of the Physical Layer
Ethernet cables, fiber optics, Wi-Fi signals.
Hubs, repeaters.
Examples of the Data Link Layer
Ethernet (IEEE 802.3), Wi-Fi (IEEE 802.11).
Switches, bridges.
Examples of the Network Layer
Internet Protocol (IP), IPv4, IPv6.
Routers.
Examples of the Transport Layer
TCP, UDP.
Port numbers (e.g., port 80 for HTTP, port 443 for HTTPS).
Examples of the Session Layer
Session management in Remote Procedure Calls (RPC).
NetBIOS, SMB.
Examples of the Presentation Layer
SSL/TLS encryption.
Data formats like JPEG, PNG, MP4, ASCII, EBCDIC.
Examples of the Application Layer
HTTP/HTTPS (web browsing), SMTP (email), FTP (file transfer), DNS (domain name resolution).
