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Transmission Control Protocol/Internet Protocol (TCP/IP)

What is Transmission Control Protocol/Internet Protocol?

Transmission Control Protocol (TCP) is the default communication method, that is used on top of Internet Protocol (IP), which enables application programs and computing devices to exchange messages over a network. TCP establishes and maintains a connection between the sender and the receiver during the transferring process and its mechanisms ensure that all pack data arrives unaltered. TCP is one of the basic standards that define the rules of the internet, and it is included within the standards that were defined by the Internet Engineering Task Force (IETF)1. Advantages of TCP include:

  • A connection-oriented reliable service. TCP guarantees the delivery of data packets. If the data packet is lost across the network, then the TCP will resend the lost packets.
  • Providing a flow control mechanism using a sliding window protocol.
  • Providing error detection by using checksum and error control by using Go Back or ARP protocol.
  • Eliminating the congestion by using a network congestion avoidance algorithm that includes various schemes such as additive increase/multiplicative decrease (AIMD), slow start, and congestion window.

The TCP/IP model has four layers2:

Application layer. The application layer refers to programs that need TCP/IP to help them communicate with each other. Users typically interact with this layer in programs such as email systems and messaging platforms.

Transport layer. The transport layer is responsible for providing a solid and reliable data connection between the original application or device and its intended destination. On this level, data is divided into packets and numbered to create a sequence, then the transport layer determines how much data must be sent, where it should be sent to, and at what rate. It ensures that data packets are sent without errors and in sequence and obtains the acknowledgment that the destination device has received the data packets.

Internet layer. The internet layer is responsible for sending packets from a network and managing their movement across a network to ensure they reach their destination. The internet layer provides the functions and procedures for transferring data sequences between applications and devices across networks.

Datalink layer. The datalink layer defines how data should be sent, handles the sending and receiving data, and is responsible for transmitting data between applications or devices on a network. The datalink layer defines how data should be signaled by hardware and other transmission devices on a network. It is also referred to as the link layer, network access layer, network interface layer, or physical layer.

IETF, 1981, “Transmission Control Protocol”

Fortinet, 2023, “What is Transmission Control Protocol TCP/IP?”