Explaining the TCP/IP Stack of Protocols

In order to fully understand networking, no conversation would be complete without discussing the TCP/IP Stack of Protocols. In this article, we will explain the TCP/IP Stack and explain how it is used to facilitate communications over the Internet, using various familiar protocols within the stack that you may be familiar with, such as HTTP (80), or HTTPS (443) and many more from the 65,535 ports/services available in the TCP/IP Stack. Let’s get into it!

The TCP/IP stack is a collection of protocols that are used to transfer data over the internet. The name “TCP/IP” stands for Transmission Control Protocol/Internet Protocol, and these protocols form the backbone of all internet communication. In this article, we will delve into the various layers of the TCP/IP stack and how they work together to facilitate communication between computers.

The TCP/IP stack can be thought of as having four main layers: the application layer, the transport layer, the network layer, and the link layer. Each layer serves a specific purpose and operates at a different level of abstraction.

The application layer is the topmost layer of the TCP/IP stack and is closest to the end user. This layer includes applications such as web browsers, email clients, and instant messaging programs. The application layer is responsible for providing the user with an easy-to-use interface for accessing the network. Applications at this layer communicate through well-known port numbers, such as HTTP (Hypertext Transfer Protocol) on port 80, FTP (File Transfer Protocol) on port 21, and SMTP (Simple Mail Transfer Protocol) on port 25.

The transport layer sits below the application layer and provides reliable communication between applications running on different computers. This layer uses protocols such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) to accomplish this. The TCP protocol operates on well-known port numbers, such as port 80 for HTTP and port 443 for HTTPS (Hypertext Transfer Protocol Secure). The UDP protocol operates on ephemeral port numbers that are dynamically assigned as needed.

The network layer is located below the transport layer and is responsible for routing data between computers on the network. This layer uses the IP (Internet Protocol) to accomplish this. The IP addresses packets of data and forwards them from one computer to another.

The link layer is the lowest layer of the TCP/IP stack and is responsible for transmitting data over a specific link, such as a wired or wireless network. This layer uses protocols such as Ethernet and Wi-Fi to accomplish this.

In summary, the TCP/IP stack is a set of protocols that are used to transfer data over the internet. The four main layers of the TCP/IP stack each serve a specific purpose and operate at a different level of abstraction. By working together, these protocols enable the transfer of data between computers in a reliable and efficient manner. The use of well-known and ephemeral port numbers at the transport layer ensures that data is properly routed to the correct application.