IPv4: What is it?

IPv4: what is it?

The Internet is a network designed for data exchange. Searching for encyclopedic articles, music, videos, films, receiving and sending messages - all these are options for information exchange. It is impossible to imagine the modern world without the Internet, however, not every user has even a rough idea of ​​how it works and is arranged.

In order for data to successfully arrive at a specific device, be it a smartphone or a computer, special protocols are used, the most common of which is IPv4. How and when did it appear? What is the principle of operation? What are the main features?

Brief history

The predecessor of the modern Internet was the ARPAnet network, the initiator of which was the US Department of Defense. It appeared in 1969, data exchange was carried out between 4 hosts, however, by 1981 the number had grown to 213. The network expanded, divided into groups and segments, the complexity of the structure led to the fact that the search for a way to establish effective interaction between all structures became increasingly relevant.

The main task of specialists had a clear formulation - to preserve the initial heterogeneity of all networks while ensuring effective interaction of clients connected to them. The solution was proposed by Vinton Cerf and Robert Khan. It was the IPv4 protocol. In 1981, it began to spread, and by 1983 it had replaced NCP, used in the ARPAnet.

Principle of operation

IPv4 is a protocol that operates at the network and internetwork levels. Its most important function is to transmit data packets from senders to recipients, which are various devices, servers, computers. If necessary, the protocol can also handle secondary tasks:

• Information fragmentation;
• Data compression.

Extended functionality makes it possible to establish effective interaction between any networks, regardless of scale and devices connected to them.

A datagram, a packet of sent data, must have a unique header and payload. The header is needed to encrypt the sender and recipient addresses, while the payload is understood to be the main information. A feature that distinguishes IPv4 from direct communication protocols is the packet transmission method, which eliminates the connection break if even one switching module fails. The method is also resistant to packet loss; support for repeated requests is provided for their recovery.

Each device operating under the IPv4 protocol has a unique IP address, which ensures the accuracy of information transfer, eliminates unnecessary complications and delays when setting up switching. Addresses are presented in two large categories, private and public. Public ones are unique and, in most cases, unchangeable, belong to large servers, private ones are assigned to each device that reconnects to the network, and therefore can change, there is no permanent binding.

IP address composition

In the IPv4 version, the address consists of 32 bits of information, which is enough for successful identification. It is written - 4 numerical groups, each of which can be formed by a maximum of 3 digits. A clear example of writing can be “172.16.254.1.”, the minimum address is 4 zeros separated by dots, the maximum is “255.255.255.255”, that is, exceeding the number “255” is unacceptable.

Classification of addresses

In networks operating on the IPv4 protocol, addresses of several classes are used:

• A – possible values ​​– from “0.0.0.0” to “127.255.255.255”. This category is focused on large-scale networks.
• B – large-scale and medium-scale networks, values ​​– from “128.0.0.0” to “191.255.255.255”.
• C – the permissible range is from “192.0.0.0” to “223.255.255.255”, which ensures ideal compatibility with local-scale networks.

There are also specialized classes, D and E. The first is focused on software whose operation involves sending packets to several addresses at once, the second is experimental.

Addressing modes

The IPv4 protocol supports several addressing schemes:

• Unicast. In this format, information is transmitted to a single network module that can act as both a sender and a receiver. In most cases, the mode is used when accessing the connection protocol.
• Broadcast. This scheme implies that each device connected to the corresponding network can interact with the transmitted data packets. The format is made possible by adding a special identification code.
• Multicast. This scheme combines the formats described above, is the most universal and functional.

IPv4 packet structure

The transmitted data packet contains not only the main set of information, but also an auxiliary one, ensuring clarity, stability of switching, timely delivery and sending. The most significant structural parts are the following:

• Time to live. It is designated by the English abbreviation “TTL”. Correctly set time to live eliminates the risk of looping, endless transmission of the packet. The fact of receipt by one device reduces the TTL by one, when it reaches zero, the transmission stops.
• Internet protocol. The information indicates a higher-level protocol, which expands the scope of IPv4.
• Sender address. A unique identifier of the device that generated the packet.
• Recipient address. Identifier of the device to which the information should be delivered. It is assigned regardless of the sending format, from unicast to broadcast.
• Data. The main set of data transmitted between the sender and the recipient is designated by the term “Data”.

Protocol status in the OSI reference network model

The OSI model was created specifically to clearly represent the interaction of equipment connected to the network. It is based on a strict hierarchy, consists of 7 levels, from physical to application.

The IPv4 protocol belongs to the network layer, which occupies the third position in the general hierarchical structure. The main function of this level is to determine the optimal routes for information transmission, ensuring maximum speed, stability of delivery, taking into account the current load of the network as a whole and each individual device, which eliminates failures and loss of information.

The network layer also performs tasks related to translation, logical network addresses are transformed into physical ones, or the reverse transformation occurs. The third level is an intermediary that receives data from the fourth level, fragments it, adds auxiliary data for successful transmission to the second.

Advantages and disadvantages

The main strengths of the IPv4 protocol are as follows:

• Universality, compatibility with networks of various sizes, confident operation on all network devices, be it routers, computers, smartphones.
• Simplicity of topology, which simplifies the implementation of the network, its basic setup and further management, configuration.
• Brief writing of IP addresses, simplifying the recording. If necessary, you can even remember the numbers, the format is no more complicated than a mobile phone number.
• Support for encryption algorithms, which increases the security of data transfer, makes their interception useless, without knowledge of encodings, decryption is impossible.
• Support for multicast, which is especially important for audio and video streaming services.

The main disadvantage of IPv4 is the limited number of available addresses. Their number is more than 4 billion, however, given the constantly increasing number of subscribers, it does not seem sufficient. Authoritative organizations representing the field of Internet communications are unanimous in the opinion that very soon there will be no free addresses left in this segment, new subscribers will have to not only buy them, but wait for them to become available.

The second negative point is the initial lack of IPsec support. Activation is possible, however, it is much easier to do this from a new address.

Technology development

A more modern version of the Internet protocol, devoid of the shortcomings of IPv4 is IPv6. Its creation dates back to 1995. The number of available addresses within IPv6 is essentially unlimited, amounting to almost 80 octillion, which solves the main disadvantage of IPv4 - the number of identifiers that does not correspond to the real needs of subscribers. Other advantages of the updated version are as follows:

• Increased routing efficiency, which allows you to simplify the structure of the routing table, increase overall stability, accuracy, and speed.
• Increased efficiency of interaction with information packets due to header optimization.
• Basic support for QoS technology, eliminating delays in data transmission.
• Support for IoT technology. Thanks to its simplified information structure and more efficient packet processing, the new protocol is better suited for connecting network equipment with low computing power and low energy consumption.

Despite the advantages of IPv6, many users remain on IPv4 addresses. Its prevalence is limited by both technical and financial factors, but the number of addresses used by the new protocol is steadily growing. In the future, it can be expected that IPv4 will be completely replaced by the sixth version.

Author of the article:

Editor-in-Chief

Danaev Almaz