Difference between original and modern TCP/IP models

TCP/IP is a networking model. It has two variations. The original model consists of four layers, while the modern model has five. The modern TCP/IP model separates the physical link layer into two distinct layers and renames the internet layer as the network layer. This tutorial compares both variations and explains their differences.

The Original TCP/IP Layered Model

The original TCP/IP model, as outlined in RFC 1122, specifies how computers communicate within a network. It establishes the necessary standards, protocols, references, and specifications for network communication. Standards and protocols are defined through documents known as Requests for Comments (RFCs).

This model does not redefine standards or protocols already established by other vendors or standards organizations. If a protocol or standard exists, it references that to avoid redundancy. For example, the model did not redefine Ethernet LAN specifications, since these were already established by the IEEE prior to the model’s development. Instead, it incorporated these existing standards by reference, ensuring compatibility and avoiding redundancy.

The original TCP/IP model divides the communication process into four layers: application, transport, internet, and link. The application and transport layers address the needs of applications that send and receive data. The internet layer manages data delivery across the entire network path, while the link layer handles data transmission over physical connections.

The Modern TCP/IP Layered Model

The modern TCP/IP layered model updates the original structure. The application and transport layers remain unchanged from the original model. The internet layer is renamed the network layer. The link layer is divided into two sublayers: the data link and the physical. The physical layer specifies physical media and associated standards. The data link layer defines protocols for converting data into signals.

Similarities Between the Original and Modern TCP/IP Models

• Both models describe the mechanisms by which computers communicate within a network.
• Both models segment the communication process into distinct layers.
• Both models utilize RFCs to define standards and protocols.
• Both models reference external standards and protocols defined by other organizations.
• The application and transport layers remain consistent across both models.

Differences Between the Original and Modern TCP/IP Models

• The original TCP/IP model defines communication standards and protocols across four layers, whereas the modern model employs five layers.
• The original model utilizes a single link layer to describe protocols that convert data into electrical signals and radio waves, as well as the specifications for the transmission media.
• The modern model assigns the physical layer to specify the transmission media, while the data link layer defines the protocols that convert data into signals.
• Additionally, the modern model renames the internet layer as the network layer.

Conclusion

Both the original and modern TCP/IP models provide foundational frameworks for network communication. While they share core similarities, the evolution from four to five layers and the refinement of terminology in the modern model reflect technological advances and the increasing complexity of networks. Understanding these differences is essential to understanding how network protocols and standards have evolved over time.