The TCP/IP Model

Exploring the 4-layer practical model that powers the Internet.

A Practical Framework for the Internet

While the OSI model is a comprehensive, theoretical framework, the TCP/IP model is the practical protocol suite that powers the modern internet. Developed before the OSI model, it consists of four layers that describe the real-world communication process. Unlike the OSI model's seven layers, the TCP/IP model combines several functions into fewer layers, reflecting a more streamlined, implementation-focused approach.

This model enables not just the exchange of data between computers but also the identification and routing of that data to the correct destinations across the global network. Its flexibility is key to its success, allowing it to be used for everything from voice calls and video streaming to web browsing.

The Four Layers of the TCP/IP Model

The TCP/IP suite is structured into four distinct layers, each with its own set of responsibilities and protocols.

4. Application Layer

This is the top layer where users and applications directly interact with the network. It handles specific tasks related to data exchange and communication, using protocols tailored for different services.

  • Responsibilities: Direct interaction with user applications, data representation, encoding, and dialogue control.
  • Key Protocols: , , , .

3. Transport Layer

This layer is responsible for providing reliable end-to-end data transfer between devices. It handles issues like data segmentation, error control, and flow control to ensure data arrives correctly.

  • Responsibilities: Reliable data delivery, error checking, segmentation.
  • Key Protocols: , .

2. Internet Layer

This is where data is addressed and routed to its proper destination on the network. It is the core of the TCP/IP model, responsible for moving packets across different networks (internetworking).

  • Responsibilities: Logical addressing, routing, packet forwarding.
  • Key Protocols: is the central element of this layer.

1. Network Access Layer

This layer is responsible for the physical transmission of data between devices on the same network. It deals with the hardware specifics, such as the type of cabling and signaling.

  • Responsibilities: Physical data transmission.
  • Key Technologies: , .

Comparing the TCP/IP and OSI Models

While both models describe network communication, they differ in their number of layers and how they group functions. The TCP/IP model is more of a "descriptive" model that matches the protocols which were actually developed, whereas the OSI model is a "prescriptive" model that provides a more detailed, theoretical guideline.

Explore the TCP/IP stack

Toggle the view, compare it with OSI and inspect the services, protocols and media that live on each layer.

Layer order
Focus

Layer 1 of 4

Layer 4 · Application

Data
  • Shapes data for specific services and takes care of dialogue control and formatting.
  • Negotiates formats, authentication and presentation so that clients understand responses.
Active path
Layers already traversed in this direction
L4 · Data

Selected layer

Drag the handle or tap a layer tile to switch.

Layer 4 · Application
L4L3L2L1

How the Layers Map

  • The TCP/IP Application Layer corresponds to the OSI Application, Presentation, and Session layers (Layers 7, 6, 5).
  • The TCP/IP Transport Layer maps directly to the OSI Transport Layer (Layer 4).
  • The TCP/IP Internet Layer maps directly to the OSI Network Layer (Layer 3).
  • The TCP/IP Network Access Layer corresponds to the OSI Data Link and Physical layers (Layers 2, 1).
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