What layer in the Transmission Control Protocol Internet Protocol model is responsible for delivering data?

TCP stands for Transmission Control Protocol a communications standard that enables application programs and computing devices to exchange messages over a network. It is designed to send packets across the internet and ensure the successful delivery of data and messages over networks.

TCP is one of the basic standards that define the rules of the internet and is included within the standards defined by the Internet Engineering Task Force (IETF). It is one of the most commonly used protocols within digital network communications and ensures end-to-end data delivery.

TCP organizes data so that it can be transmitted between a server and a client. It guarantees the integrity of the data being communicated over a network. Before it transmits data, TCP establishes a connection between a source and its destination, which it ensures remains live until communication begins. It then breaks large amounts of data into smaller packets, while ensuring data integrity is in place throughout the process.

As a result, high-level protocols that need to transmit data all use TCP Protocol.  Examples include peer-to-peer sharing methods like File Transfer Protocol (FTP), Secure Shell (SSH), and Telnet. It is also used to send and receive email through Internet Message Access Protocol (IMAP), Post Office Protocol (POP), and Simple Mail Transfer Protocol (SMTP), and for web access through the Hypertext Transfer Protocol (HTTP).

An alternative to TCP is the User Datagram Protocol (UDP), which is used to establish low-latency connections between applications and decrease transmissions time. TCP can be an expensive network tool as it includes absent or corrupted packets and protects data delivery with controls like acknowledgments, connection startup, and flow control. 

UDP does not provide error connection or packet sequencing nor does it signal a destination before it delivers data, which makes it less reliable but less expensive. As such, it is a good option for time-sensitive situations, such as Domain Name System (DNS) lookup, Voice over Internet Protocol (VoIP), and streaming media.

What is IP?

The Internet Protocol (IP) is the method for sending data from one device to another across the internet. Every device has an IP address that uniquely identifies it and enables it to communicate with and exchange data with other devices connected to the internet.

IP is responsible for defining how applications and devices exchange packets of data with each other. It is the principal communications protocol responsible for the formats and rules for exchanging data and messages between computers on a single network or several internet-connected networks. It does this through the Internet Protocol Suite (TCP/IP), a group of communications protocols that are split into four abstraction layers.

IP is the main protocol within the internet layer of the TCP/IP. Its main purpose is to deliver data packets between the source application or device and the destination using methods and structures that place tags, such as address information, within data packets.

TCP vs. IP: What is the Difference?

TCP and IP are separate protocols that work together to ensure data is delivered to its intended destination within a network. IP obtains and defines the address—the IP address—of the application or device the data must be sent to. TCP is then responsible for transporting and routing data through the network architecture and ensuring it gets delivered to the destination application or device that IP has defined. 

In other words, the IP address is akin to a phone number assigned to a smartphone. TCP is the computer networking version of the technology used to make the smartphone ring and enable its user to talk to the person who called them. The two protocols are frequently used together and rely on each other for data to have a destination and safely reach it, which is why the process is regularly referred to as TCP/IP.

How Does TCP/IP Work?

The TCP/IP model is the default method of data communication on the Internet.  It was developed by the United States Department of Defense to enable the accurate and correct transmission of data between devices. It breaks messages into packets to avoid having to resend the entire message in case it encounters a problem during transmission. Packets are automatically reassembled once they reach their destination. Every packet can take a different route between the source and the destination computer, depending on whether the original route used becomes congested or unavailable.

TCP/IP divides communication tasks into layers that keep the process standardized, without hardware and software providers doing the management themselves. The data packets must pass through four layers before they are received by the destination device, then TCP/IP goes through the layers in reverse order to put the message back into its original format. 

As a connection based protocol, the TCP establishes and maintains a connection between applications or devices until they finish exchanging data. It determines how the original message should be broken into packets, numbers and reassembles the packets, and sends them on to other devices on the network, such as routers, security gateways, and switches, then on to their destination. TCP also sends and receives packets from the network layer, handles the transmission of any dropped packets, manages flow control, and ensures all packets reach their destination.

A good example of how this works in practice is when an email is sent using SMTP from an email server. To start the process, the TCP layer in the server divides the message into packets, numbers them, and forwards them to the IP layer, which then transports each packet to the destination email server. When packets arrive, they are handed back to the TCP layer to be reassembled into the original message format and handed back to the email server, which delivers the message to a user’s email inbox.

TCP/IP uses a three-way handshake to establish a connection between a device and a server, which ensures multiple TCP socket connections can be transferred in both directions concurrently. Both the device and server must synchronize and acknowledge packets before communication begins, then they can negotiate, separate, and transfer TCP socket connections.

The 4 Layers of the TCP/IP Model

The TCP/IP model defines how devices should transmit data between them and enables communication over networks and large distances. The model represents how data is exchanged and organized over networks. It is split into four layers, which set the standards for data exchange and represent how data is handled and packaged when being delivered between applications, devices, and servers.

The four layers of the TCP/IP model are as follows:

1. Datalink layer: The datalink layer defines how data should be sent, handles the physical act of sending and receiving data, and is responsible for transmitting data between applications or devices on a network. This includes defining how data should be signaled by hardware and other transmission devices on a network, such as a computer’s device driver, an Ethernet cable, a network interface card (NIC), or a wireless network. It is also referred to as the link layer, network access layer, network interface layer, or physical layer and is the combination of the physical and data link layers of the Open Systems Interconnection (OSI) model, which standardizes communications functions on computing and telecommunications systems.
2. Internet layer: The internet layer is responsible for sending packets from a network and controlling their movement across a network to ensure they reach their destination. It provides the functions and procedures for transferring data sequences between applications and devices across networks.
3. 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. This is the level where data is divided into packets and numbered to create a sequence. The transport layer then 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.
4. Application layer: The application layer refers to programs that need TCP/IP to help them communicate with each other. This is the level that users typically interact with, such as email systems and messaging platforms. It combines the session, presentation, and application layers of the OSI model.

Are Your Data Packets Private Over TCP/IP?

Data packets sent over TCP/IP are not private, which means they can be seen or intercepted. For this reason, it is vital to avoid using public Wi-Fi networks for sending private data and to ensure information is encrypted. One way to encrypt data being shared through TCP/IP is through a virtual private network (VPN).

What is My TCP/IP Address?

A TCP/IP address may be required to configure a network and is most likely required in a local network.

Finding a public IP address is a simple process that can be discovered using various online tools. These tools quickly detect the IP address of the device being used, along with the user’s host IP address, internet service provider (ISP), remote port, and the type of browser, device, and operating system they are using. 

Another way to discover the TCP/IP is through the administration page of a router, which displays the user’s current public IP address, the router’s IP address, subnet mask, and other network information.

How Fortinet Can Help?

Fortinet enables organizations to securely share and transmit data through the TCP/IP model with its FortiGate Internet Protocol security (IPsec)/secure sockets layer (SSL) VPN solutions. Fortinet's high-performance, scalable crypto VPNs protect organizations and their users from advanced cyber attacks, such as man-in-the-middle (MITM) attacks, and the threat of data loss while data is in motion at high speed. This is crucial for data being transmitted through TCP/IP, which does not protect data packets while they are in motion.

The Fortinet VPN solutions secure organizations’ communications across the internet, over multiple networks, and between endpoints. It does this through both IPsec and SSL technologies, using the Fortinet FortiASIC hardware acceleration to guarantee high-performance communications and data privacy.

Fortinet’s VPNs mask a user’s IP address and create a private connection for them to share data regardless of the security of the internet connection they are using. They establish secure connections by encrypting the data being transmitted between applications and devices. This eliminates the risk of sensitive data being exposed to third parties while being transferred over TCP/IP, in addition to hiding the users' browsing histories, IP addresses, locations, web activities, and other device information.

FAQs

What is TCP used for?

TCP enables data to be transferred between applications and devices on a network and is used in the TCP IP model. It is designed to break down a message, such as an email, into packets of data to ensure the message reaches its destination successfully and as quickly as possible.

What does TCP mean?

TCP meaning Transmission Control Protocol, is a communications standard for delivering data and messages through networks. TCP is a basic standard that defines the rules of the internet and is a common protocol used to deliver data in digital network communications.

What is TCP and what are its types?

TCP is a protocol or standard used to ensure data is successfully delivered from one application or device to another. TCP is part of the Transmission Control Protocol/Internet Protocol (TCP/IP), which is a suite of protocols originally developed by the U.S. Department of Defense to support the construction of the internet. The TCP/IP model consists of several types of protocols, including TCP and IP, Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), Reverse Address Resolution Protocol (RARP), and User Datagram Protocol (UDP).

TCP is the most commonly used of these protocols and accounts for the most traffic used on a TCP/IP network. UDP is an alternative to TCP that does not provide error correction, is less reliable, and has less overhead, which makes it ideal for streaming.

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