Model ISO - OSI
What is ISO OSI model
ISO OSI = International Organization for Standardization Open Systems Interconnection
ISO OSI model is conceptual framework:
- used to standardize and understand how different networking protocols and functions interact within a networks
- consists of seven layers, each with a specific role and set of functions
Physical Layer (Layer 1):
- the lowest layer
- deals with the physical aspects of data transmission.
- defines the physical medium, such as cables, electrical voltages, or optical signals, and how data is transmitted over them.
- example: Ethernet cables, fiber optic connections, and wireless communication signals.
Data Link Layer (Layer 2):
- responsible for framing data for transmission and detecting and correcting errors in the data
- manages access to the physical medium
- resolves issues related to the physical addressing of devices on a local network.
- examples: Ethernet and Wi-Fi
Network Layer (Layer 3):
- focuses on routing and forwarding data between different networks or subnets.
- uses logical addressing (such as IP addresses) to determine the best path for data to travel from source to destination
- exampkes: routers operate at this layer
Transport Layer (Layer 4):
- manages end-to-end communication and data segmentation into smaller packets.
- provides error detection, flow control, and data integrity, ensuring that data is reliably and accurately delivered
- examples: Protocols like TCP (Transmission Control Protocol) and UDP (User Datagram Protocol)
Session Layer (Layer 5):
- establishes, maintains, and terminates connections between two devices or applications
- manages session synchronization and ensures that data is delivered in the correct order
- examples: NetBIOS and RPC (Remote Procedure Call)
Presentation Layer (Layer 6):
- responsible for data translation, encryption, and compression.
- ensures that data is in a format that both the sender and receiver can understand.
- can handle data compression and encryption as needed.
Application Layer (Layer 7):
- the topmost layer, the closest to end-users and applications
- provides network services directly to end-users and applications (usually through language or libraryAPI) and is where most user-facing software interacts with the network
- Common application layer protocols include HTTP (for web browsing), SMTP (for email), and FTP (for file transfer)