What is Internet Protocol IP

TCP / IP

The abbreviation TCP / IP stands for the two protocols Transmission Control Protocol (TCP) and Internet Protocol (IP). Together with many other protocols, TCP / IP is a protocol family for the switching and transport of data packets in a decentralized and global network. In order to enable end-to-end communication from host to host across network boundaries, communication protocols that are used in the LAN (Local Area Network) and in the WAN (Wide Area Network) are required.
The success of the Internet, as a communication network available worldwide, is in large part due to the TCP / IP protocols.

TCP / IP in the DoD and OSI layer model

DoDLayer modelsOSI
4. ApplicationHTTP, FTP,
SMTP, POP, IMAP, ...
7. Application
6. Representation
5. Communication
3. TransportationTCP / UDP4. Transportation
2. MediationIPv4 / IPv63. Mediation
1. Network accessIEEE 802.3 (Ethernet),
IEEE 802.11 (WLAN), ...
2. Backup
1. Bit transfer

Within the DoD and OSI layer model, TCP / IP forms the backbone for all communication connections.

Tasks and functions of TCP / IP

The central task of TCP / IP is to ensure that data packets arrive at the recipient within a decentralized network. For this purpose, TCP / IP provides the following central functions.

  • Logical addressing (IP)
  • Pathfinding / Routing (IP)
  • Error handling and flow control / Error Control and Flow Control (TCP)
  • Application support (TCP / UDP)
  • Name resolution (DNS)

The peculiarities and problems of packet-oriented data transmission are very diverse and therefore require special solutions and functions, which are not all taken into account at this point. The following illustration and description is only a selection of the most important functions.

Logical addressing (IP)

In a simple, local network, every network adapter receives every data packet. This is the case when, due to the principle involved, all network participants have to share the transmission medium (e.g. with WLAN or Ethernet). This is a practicable solution for networks with few participants. But in a network with many thousands or even millions of participants, it makes little sense if data packets get into parts of the network where the destination is not. Whether a data packet reaches its correct recipient would then be left to chance. Therefore a possibility is required to structure the network physically (topology) and also logically (addressing). Within TCP / IP, the Internet Protocol (IP) handles the logical addressing of networks and their participants. Data packets only get into the network in which the destination is located. The methods of addressing are, for example, firmly defined network classes, subnetting and CIDR.

Pathfinding / Routing (IP)

While the logical addressing by IP ensures that a large network is divided into segments, routing, as a type of path finding, ensures that a data packet reaches its destination via the individual network segments. The next network node is determined for each individual data packet in each network node on the way from the transmitter to the receiver. In this way, a data packet finds its way to its recipient, even if it is in an unknown network segment.

Error handling and flow control / Error and Flow Control (TCP)

Thanks to TCP, the sender and receiver are in constant contact with each other (connection management). Although it is more of a virtual connection, control messages are constantly exchanged during data transmission, which is why we speak of connection-oriented communication. If an error is found, the relevant data packet is retransmitted.
In addition, a data flow control is necessary in order to utilize the available transmission speed. Because there is no exclusive channel with a fixed transmission speed for an end-to-end connection on the Internet, automatic adjustment is required here.

Application support (TCP / UDP)

Similar to how computers are addressed with IP addresses in networks, a distinction must be made between the communication links between specific applications that run together on one computer. TCP and UDP ports (numbers) form a software abstraction in order to be able to differentiate between specific applications and their communication connections.

Name resolution (DNS)

In a TCP / IP network, connections are established between the network participants with IP addresses. An IP address originally has the binary form or notation and is thus a sequence of 1s and 0s with which electronic circuits and digital programs work. For better readability, IP addresses are shown in decimal (IPv4) or hexadecimal (IPv6) notation. But neither the bit sequence nor any other notation are easy for the human brain to grasp and remember. People prefer to use names to name and identify something. Therefore, instead of IP addresses, names are used for addressing at the application level. Name resolution is necessary so that a connection at IP level is possible. What is meant is that an associated IP address must be determined for a computer or domain name. This is known as name resolution.

Advantages of TCP / IP

TCP / IP has several key advantages. With TCP / IP, every application is able to transmit and exchange data over every network. It doesn't matter where the communication partners are. The Internet Protocol (IP) ensures that the data packet reaches its destination and the Transmission Control Protocol (TCP) controls the data transmission and ensures that the data stream and application are assigned.

The type of physical and logical data transmission should not play a role for the applications. The user should also not have to worry about establishing and clearing connections. As long as the user knows a correct address, TCP / IP will take care of establishing and clearing the connection and transferring it to the destination. It doesn't matter which application or which transmission path is used.

  • TCP / IP is a global standard and is not tied to any manufacturer.
  • TCP / IP can be implemented on simple computers and on supercomputers.
  • TCP / IP can be used in LANs and WANs.
  • TCP / IP makes the application independent of the transmission system.

Disadvantages of TCP / IP

However, TCP / IP is anything but an efficient method of transferring data. The data is divided into small data packets. So that the recipient of a data packet knows what to do with it, the data packet is preceded by a header record. For each data packet, there is an administrative share of at least 40 bytes per TCP / IP data packet. Only when data packets of several kByte are formed does the administrative share remain low compared to the payload.

If the application makes certain demands on the transmission system, then this is very difficult to implement. Internal system communication between the application and the transmission system via TCP / IP is not provided.
A coordinated exchange of connection quality and requirements between network nodes is also very difficult to implement across networks. There is Quality of Service (QoS). But this is optional and requires control over the network, which is not provided for in a decentralized network such as the Internet.

In this context, one speaks of net neutrality. Net neutrality requires that every packet be treated equally. This has the disadvantage that certain data packets cannot be prioritized. This in turn has the consequence that certain applications on the Internet do not work well with TCP / IP.

IP - Internet Protocol

The Internet Protocol, or IP for short, has the main task of addressing data packets and transmitting them in a connectionless packet-oriented network (routing). For this purpose, all hosts and end devices have their own IP address. The IP address is not only used to address individual hosts, but entire networks. IP routing is not about sending data packets to specific hosts, but about routing the packets to the correct network.
A distinction is made between IPv4 and its successor IPv6.

TCP - Transmission Control Protocol

In the TCP / IP protocol family, TCP, as a connection-oriented protocol, takes on the task of application allocation, data flow control and takes measures in the event of a packet loss. The way TCP works is to receive the files or the data stream from the applications, to split them up, to add a header and to pass them on to the Internet Protocol (IP).
At the recipient, the data packets are reassembled in the correct order and passed on to the correct application. The assignment takes place via a port number. The ports enable several applications to establish connections to different communication partners at the same time.
The little brother of TCP is UDP, which is a stripped-down transport protocol.

Other important protocols of the TCP / IP protocol family

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