The Internet Protocol version 4 (IPv4) offers hierarchical addressing for packets carrying data, video, etc. As mentioned above, it is based on the binary number system, only comprised of 1’s and 0’s, the definitions and examples that we will use to explain IPv4 are designed to be understood easily and simply. However, if you do not know how binary code works, we recommend that you research this system to complement it.
For this article, the following basic terms should be kept in mind:
- Bit: Acronym for Binary Digit, Bit is a digit of the binary system that can represent only two values; these values are 0 or 1.
- Byte: a group or set of 8 bits.
- Octet: another way of naming a Byte.
IPv4 was implemented in 1983 for the operation of ARPA and is defined in RFC 791, which specifies that IPv4 addresses consist of 32 bits each, for example:
11000000 10101000 00000001 00000001
As you can see in the last line, an IPv4 address is represented. Unfortunately, the understanding and comprehension of this series of zeros and ones are complex to remember and manipulate. For this reason, a decimal format with dots is used to represent it; the binary patterns that represent the IPv4 addresses are expressed with decimal points separating each byte of the binary pattern, called octet, with a dot. It is called an octet because each decimal number represents one byte or 8 bits.
With this format, the above IP address would look like this:
To fully understand IPv4 addresses, knowing the conversion from Binary to Decimal Code and vice versa.
Understanding the structure of IPv4 and its conversion from binary to decimal and vice versa, let’s explore the types of addresses that are within the address range of each IPv4 network; there are three types of addresses:
- Network address: The network address is a standard way of referring to a network. For example, you could refer to the network 10.0.0.0.0; this is a much more convenient and descriptive way of referring to the network than using a term such as “the first network”. All hosts on the 10.0.0.0.0 network will have the same network bits. Within the IPv4 address range of a network, the lowest address is reserved for the network address. This address has a 0 for each host bit in the host part of the address.
- Broadcast address: The IPv4 broadcast address is a special address for each network that allows communication to all hosts on that network. To send data to all hosts on a network, a host can send a single packet addressed to the network’s broadcast address. The broadcast address uses the highest address in the network range. This is the address in which the bits in the host portion are all 1. For the network 10.0.0.0.0 with 24 network bits, the broadcast address would be 10.0.0.255. This address is known as a directed broadcast.
- Host addresses: As described above, each end device requires a unique address to send a packet to that host. In IPv4 addressing, the values between the network address and the broadcast address are assigned to the devices on that network.