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IPv4 address

Due to the rapidly increasing number of Internet subscribers, the address space of classic IP addresses was limited, especially since IP addresses had to be classified into network identifier( net-id) and host identifier. This fixed IP class division severely restricted the flexibility of address allocation, which meant that a large proportion of IP addresses could not be used. It was therefore abolished as early as 1993 and replaced by Classless Interdomain Routing( CIDR), which works with subnet classes and supports more efficient address utilization.

The CIDR method is used in IPv4 addresses and later also in IPv6 addresses. IPv4 has a theoretical address scope of 4,294,967,296 IP addresses thanks to Classless Interdomain Routing, which results from the address scope of 32 bits. These IPv4 addresses can be divided into a network identifier (netid) and host identifier( host-id) via the subnet mask, just like the classic IP addresses. In contrast to the classic IP address, the division can be done not only in a few classes, but by the total of 32 subnet masks in 32 classes. In the most extensive class, all addresses (`2^32`) can be assigned as host addresses, as in the Internet. With a suffix of /16, which corresponds to the Class-B address of the classic IP address, there are 65,534 (`2^16`) host addresses and 16,384 (`2^14`) network addresses. The subnet mask looks like this for an IP address with the /16 suffix:

From the classless IPv4 address, the network address and the host address can be determined by the subnet mask and the logical links of the IP address with the subnet mask.

Determining the network and host addresses for IPv4 addresses using the CIDR method

Determining the network and host addresses for IPv4 addresses using the CIDR method

Although the CIDR procedure has a much higher flexibility for IPv4 addresses, even this address space was not able to cope with the dynamics of the Internet, so with IPv6 an addressing concept was developed that covers an address space of 128 bits, which corresponds to a 39- digit decimal number.

Englisch: IPv4 address
Updated at: 22.01.2022
#Words: 315
Links: Internet, address space (AS), intelligent peripheral (IP), network, network identification (net-id)
Translations: DE

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