4. Practical Applications of the OSI Model

4.1. OSI Layer Function and Example

Layer

Summary Table

Layer

Name

Function

Examples

7

Application

User-facing services

HTTP, FTP, SMTP, DNS

6

Presentation

Data translation, encryption, compression

SSL/TLS, JPEG, PNG, MIME

5

Session

Session management, synchronization

NetBIOS, RPC, SIP, SMB

4

Transport

End-to-end reliability, flow control

TCP, UDP, port numbers

3

Network

Routing, logical addressing

IP, ICMP, routers, OSPF

2

Data Link

Node-to-node transfer, error detection

Ethernet, PPP, MAC, switches

1

Physical

Bit transmission, hardware specs

Cables, hubs, Wi-Fi signals