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Carrier-grade NAT

Carrier-Grade NAT - NAT operator class

The network address conversion mechanism enables operators to continue to use the limited IPv4 address space, maintain a large number of simultaneous connections, and simplifies the transition to IPv6 addressing. This new level of NAT development is designed for Internet service providers and operators, but is also suitable for replacing NAT devices in corporate networks. It allows you to assign local addresses to subscribers, centrally converting them into external ones.


In the early 80's of last century, the network Internet protocol IPv4 was developed and adopted. This version was the most successful, so it still exists. 4 bytes are allocated for each IP address. For this reason, our addresses consist of four blocks of decimal numbers and are preferably in the range of to Four groups of 8 bits guaranteed more than 4 billion unique IP addresses with this protocol, to be exact (4,294,967,296) - insanely huge by the standards of those years. At that time it was believed that this would be enough forever and nothing better could be invented. But the Internet grew faster than the most optimistic forecasts, and the number of devices that needed a network address was actively increasing. This was largely due to the advent of broadband internet.

When IPv4 was developed, the main way to access the World Wide Web was through a telephone modem, and there were few devices that were constantly on the network, so fewer addresses were needed. Therefore, in the early 1990s it became clear that in the future free addresses will be exhausted. To solve the global problem, a new version of the network protocol was created - Internet Protocol version 6. In principle, IPv6 can guarantee more than 300 million addresses per capita. 16 bytes (128 bits) are allocated to the IP address instead of 4. Currently, the implementation of IPv6 is taking place everywhere, including in Ukraine.

Features of NAT technology

The new protocol is the best, however, it was not possible to pass to the new standard at once. The reason is that IPv6 is not designed to be compatible. This means that a network device with an IPv6 address will not be able to communicate with a device that has an IPv4 IP address. In addition, there are many devices that are not able to support IPv6 connections, but are still fully functional for users. This state of affairs has led to the simultaneous parallel use of both versions of IP protocols. In order to somehow alleviate the situation before the general transition to IPv6, the NAT (Network Address Translation) mechanism is used, but not standard, but the operator class, the so-called Carrier-Grade NAT or CGNAT, designed for service providers and providers to use more efficiently IP range with a limited address base.

In order to understand the principle of Carrier-Grade Network Address Translation, it is necessary to mention the features of addresses in the IPv4 protocol. The entire database of available addresses is divided into two types - public or external, they are also called "white", and private, or "gray". An external IP address is used to access the global network. It can be routed on the Internet. Standard NAT technology allows you to convert (broadcast) a private IPv4 address to a public one. Operator-class network address translation (CGNAT) is a large-scale NAT that can convert private IPv4 to a public IPv4 address to support a large number of users and has a bandwidth of at least 10 Gbps. This allows ISPs, while maintaining their own public IPv4 addresses, to handle subscriber traffic over the service provider's private IPv4 network and to support subscribers or businesses that have their own private IPv4 networks and use multiple devices at the same time.

Advantages of NAT operator class

If we talk about the benefits of NAT operator class, they are as follows:

  • allows service providers to migrate to IPv6 in an orderly manner over mixed IPv4 and IPv6 networks;
  • provides translation of the address family, but is not limited to translation within one address family;
  • provides a comprehensive set of IP address management solutions and provides legacy hardware with access to IPv6.

For the provider, this is also an opportunity to significantly save addresses. A local home or office network has several public IP addresses, which, using the CG NAT mechanism, broadcast internal IP addresses that are used only within the local network and which can be significantly more in number.

Comprehensive and flexible solutions from global manufacturers! IIT Distribution provides software that enables corporate customers to use advanced solutions in the field of building and maintaining IT infrastructure and cybersecurity. Our specialists will conduct a preliminary examination of the project and assess the availability of conditions for its implementation at the enterprise.

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