What does NAT stand for

To understand why CGNAT has become a must-have solution and how it works, it is essential to know the primary reason for the emergence of the technology. First, it is necessary to clarify what is meant by "IPv4 and IPv6" because these two protocols are closely related to NAT.

What is wrong with iPv4? What is the alternative to IPv4?

There are already about 4.3 billion IPv4 addresses in use in the world. However, today that number is being stretched; no one expected such a rapid growth in consumers over just two decades. In addition, the emergence of this problem is mainly due to the widespread use of mobile devices with the number constantly growing. For more information, see IPv4 exhaustion details.

IPv4 is the fourth version of IP (Internet Protocol), it is the basis of the Internet, and establishes the rules for the functioning of computer networks on the principle of packet exchange. This protocol is responsible for establishing a connection between network nodes (computers, servers, mobile devices, etc.) based on IP addresses.

The global address space is managed by the American non-profit organization IANA, as well as five regional Internet registrars (ARIN, APNIC, AfriNIC, LACNIC, and RIPE NCC) responsible for assigning IP addresses to end users and local Internet registrars in certain territories. In early 2011, IANA allocated the remaining blocks of address space to regional operators. Then the regional registrars predicted that the addresses would be exhausted within the next five years. LACNIC and ARIN were among the first regional operators to declare the complete exhaustion of free IPv4 addresses. We decided to address this topic and see how this problem has been solved.

By the mid-1990s, IPv6 was developed as a replacement for IPv4. IPv6 is the next generation of IP. The main advantage of the IPv6 protocol is the increased size of the address from 32 bits to 128 bits, which gives an almost inexhaustible supply of unique IP addresses.

So why not just switch to IPv6? The main reason is the cost. Updating all servers, routers and switches that all this time depended only on IPv4 requires a lot of money and time.

NAT and CGNAT as solution for the problem

NAT (Network Address Translation) is a mechanism in TCP / IP networks that allows you to replace your local address with a white (public) address.

The main goal of NAT is to save public addresses. In addition, dynamic NAT, the second NAT type that translates one internal address to an external one from the provided range, can protect the local network and its devices from intrusion.

NAT allows the router to determine which services are behind the router and must be accessible from the Internet so that users can use these services from there. In simple terms, this mechanism allows all local network devices (computers, tablets, smartphones) to use a single IP address of the external interface for connection to the Internet.

CGNAT is the next level of NAT development that allows operators to extend the use of the IPv4 address space, serving a growing number of concurrent connections and facilitating a smooth migration to IPv6 addressing.

To put it simply, CGNAT pulls the public IPv4 addresses away from the customer site, where their multiplexing capacity is not efficiently exploited, to outside the centralized CGNAT, where many customer networks can share a single public IPv4 address. The solution is designed for Internet providers and telecom operators but is also suitable for replacing NAT devices in corporate networks.

CGNAT provides the most transparent way to use NAT because it includes features like Endpoint Independent Mapping (EIM), Endpoint Independent Filtering (EIF), and Hairpinning, and allows smooth migration to IPv6. Moreover, with additional features and capabilities, CGNAT is becoming the most effective solution to the IPv4 exhaustion problem. In comparison with alternative solutions, CGNAT is cost-effective and scalable and there is no risk of facing «grey» and «black» IP addresses.
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