OSI Model vs. TCP/IP Model

• These OSI model defines 7 different functions a Network must do.

• Following are the 7 layers of OSI Model:

  1. 7 - Application: Make Application network aware. Usually the API(Application Programming Interface) that happens behind Application to make it Network Aware.

  2. 6 - Presentation: Convert data that your Application can read.

  3. 5 - Session: Actual connection happens between 2 systems at Session layer.

     • TCP connection between Web Server and Web Client

     • Sending Email

     • Sharing folder between 2 computers in a LAN

     • And it's the Session layer that defines how the connectivity works

  4. 4 - Transport: Actual Data are big, and data travel through network are small chunks.

     • So, assembling and disassembling of data or Packets

     • It also makes sure that the Receiver receives Packets in order

  5. 3 - Network: Place where logical addressing works. IP Address, Routers work at layer 3.

  6. 2 - Data Link: Anything that works with MAC Addresses, works at the Data Link layer. Network Cards (NICs), Switches etc.

  7. 1 - Physical : The actual physical connection.

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• Following are the 4 layers of TCP/IP Model:

  1. 7 - Application: Application, Presentation and Session layer of OSI

  2. 2 - Transport: Does all the assembling and disassembling as well as establishing connection (TCP, UDP). (Transport and Session layer of OSI)

  3. 3 - Internet: Anything related to logical addressing, router. (Network Layer of OSI)

  4. 4 - Network Interface: All wired connection, NICs, Switches. (Network and DataLink layer of OSI)