Definition, Architecture, and Functions of Each TCP/IP Layer in a Computer Network
TCP/IP or Transmission Control Protocol/Internet Protocol is software in a computer network that is in the system because it allows one computer to another computer to transfer data or information within the network/band.
In computer networks, there are 2 types of network references that are commonly used, namely the network layer of the OSI model and the TCP IP layer. Continuing the previous article about the network layer of the OSI model, this time I will share the TCP IP layer. Unlike the OSI model, the TCP IP layer is divided into 5 layers (layers).
Various Layers in TCP / IP
TCP/IP has five levels or layers. The five indicators include:
Physical layer is the lowest layer which defines physical parameters like communication media, voltage, current, etc. This layer can differ depending on the communication and network being considered. TCP/IP is flexible enough to connect different networks and different physical media.
Network access layer is the layer whose function is to transfer data over the network. This layer has the same function as the data link and physical layer in the OSI model. This layer reliably manages the distribution of data frames over the physical media in use. This layer provides functions for detecting errors and correcting the transmitted data. Some examples of protocols used at this layer are X.25 for public networks, Ethernet for Ethernet networks, AX.25 for Packet Radio networks, etc.
Addressing, namely completing each datagram with the Internet address of the destination. The address on this protocol is known as the Internet Protocol Address (IP Address). Because the addressing (addressing) on a TCP/IP network is at this level (software), the TCP/IP network is independent of the type of media and computer used.
Routing, namely determining where the datagram will be sent in order to achieve the desired destination. This function is the most important function of the Internet Protocol (IP). As a connectionless protocol, the routing process is fully determined by the network. The sender has no control over the packets it sends to reach its destination. It is the routers on the TCP/IP network that determine the delivery of datagrams from the recipient to the destination.
Transport Layer defines ways to reliably transmit data between end-to-end hosts. This layer guarantees that the information received at the receiving end is the same as the information sent to the sender. For this reason, this layer has several important functions, including:
FlowControl. Sending data that has been broken down into packets must be arranged in such a way that the sender does not send data at a speed that exceeds the ability of the recipient to receive data.
Error detection. The sender and recipient also complete the data with several pieces of information that can be used to check the data sent are free from errors. If an error is found in the received data packet, the recipient will not receive the data. The sender will resend the data packet that contains the error. However, this can cause a significant delay.
In TCP/IP, the protocol used is Transmission Control Protocol (TCP) or User Datagram Protocol (UDP). TCP is used for applications that require data reliability, while UDP is used for applications that require short packet lengths and does not demand high reliability. TCP has flow control and error detection functions and is connection-oriented. In contrast, connectionless UDP does not have a mechanism for checking data and flow control, so UDP is also known as an unreliable protocol. For reasons of efficiency and simplicity, some applications prefer to use UDP as the transport protocol. An example is a database application that is only query and response in nature, or other applications that are very sensitive to delay such as video conferencing. Applications like this can tolerate slight errors (pictures or sound are still understandable) but will be uncomfortable to watch if there is a significant delay.
Application Layer is a layer that functions as an intermediary for interaction between users and network systems. This layer has the same function as the Application, Presentation, and Session layers in the network layer of the OSI model, besides that this layer is the last in the TCP/IP architecture which functions to define applications that run on the network. Therefore, there are many protocols at this layer, according to the number of TCP/IP applications that can run. Examples are SMTP (Simple Mail Transfer Protocol) for e-mail delivery, FTP (File Transfer Protocol) for file transfers, HTTP (Hyper Text Transfer Protocol) for web applications, NNTP (Network News Transfer Protocol) for newsgroup distribution, and others. other. Every application generally uses the TCP and IP protocols, so this whole protocol family is named TCP/IP.
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