What is Carrier Grade NAT (CGNAT)?

June 18, 2025 By Christine Margret No Comments 7 minutes

In the modern, ever more networked world, internet service providers (ISPs) are confronted with an increasing challenge: the lack of public IPv4 addresses. In order to eliminate this issue, a number of ISPs started using a technology called Carrier Grade NAT (CGNAT). CGNAT enables several users to access a shared public IP address by network-level private IP address translation. While this helps conserve IPv4 resources, it also introduces new complexities for online applications, gaming, and remote access. In this blog, we’ll explain what CGNAT is, how it works, and what it means for everyday internet users and network administrators.

What is Carrier Grade NAT (CGNAT)

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CGNAT – An Overview

Carrier Grade NAT, or CGNAT, is a technology that Internet Service Providers use to communicate public IPv4 addresses. With this, multiple users can share a single public IP address, as it routes traffic using a centralized network address translation (NAT) gateway. Since there is an escalating demand for IP addresses, the supply of IPv4 addresses is getting short. Hence, CGNAT emerges as a temporary solution to the IPv4 exhaustion issue.

The Difference Between CGNAT and Non-CGNAT

The key difference between CGNAT and traditional NAT (non-CGNAT) is where the translation takes place. In a non-CGNAT setup, NAT occurs at the customer’s home router, where private IP addresses are mapped to a single public IP assigned by the ISP. In a CGNAT environment, the ISP adds an additional layer of NAT. The customer’s router gets a private IP from the ISP, which is then translated to a public IP shared among multiple customers. This adds a third layer of IP addressing.

How Can I Tell If My Router Is Using CGNAT?

While CGNAT provides valuable benefits to ISPs, it does have some drawbacks for end consumers. To test if you are behind CGNAT, you can attempt the following easy step:

Compare Your Router’s WAN IP with Your Public IP

One of the simplest methods to test for CGNAT is to compare your router’s WAN IP with your publicly accessible IP address. If both are the same, you’re not behind CGNAT. If they are different, your ISP is probably employing CGNAT to conserve IPv4 addresses.

Here’s how to do the test:

Open your favorite web browser.
In the address bar, enter “What is my IP” and click Enter.
Write down the public IP address displayed at the top of the results.

Then, go to your router’s admin page:

Type your router’s IP address (usually 192.168.0.1 or 192.168.1.1) into the address bar of the browser.
Log in with your username and password.
Go to the Status or Network Information page.
Find the WAN IP Address displayed there.
Now, compare the two:

If your router’s WAN IP is the same as the public IP address, you are not behind CGNAT.
If the WAN IP is not the same as the public IP, then your connection is behind CGNAT, which means your ISP is using one public IP for multiple users.

What is NAT?

Network Address Translation (NAT) is a technique used to alter network address data in packet headers. This process enables more than one device on a local network to connect to the internet with one public IP address. NAT assists in saving IP addresses as well as presenting an additional layer of security.

What is an IP Address?

An Internet Protocol (IP) address is a distinct number that is assigned to every device that is attached to a network. There are two varieties: IPv4 and IPv6. IPv4 addresses are finite (approximately 4.3 billion total), and this created a demand for solutions such as NAT and CGNAT. IPv6 provides a virtually infinite number of addresses.

What is the CGNAT IP Address?

As discussed earlier, your ISP gives a public IP address to many users. Your IP can be referred to as a CGNAT IP address and usually falls under the category of 100. x.y.z addresses. If your existing IP address is in the above-mentioned range, there is a chance that your internet service provider is applying CGNAT to save IPv4 addresses.

Is It Possible to Bypass CGNAT?

You can maintain CGNAT, and it will not cause any problem unless you need port forwarding for good connectivity. Since Port Forwarding is required in many games and apps, you might need to delete or turn off CGNAT.

But is that possible? Yes, of course! Getting rid of CGNAT or opting out is a feature that is provided by some ISPs. You can call your ISP or the technical support number and mention a valid reason to opt-out of CGNAT. This will make your public IP address change. But if you are using a static IP address, you don’t have to worry because the aforementioned IP is not impacted by CGNAT.

What Are the Advantages of CGNAT?

Conserves IPv4 addresses by enabling shared use.
Delays the need for IPv6 adoption.
Reduces costs for ISPs by minimizing the purchase of additional IP blocks.
Increases IP availability in high-demand areas.

What Are the Disadvantages of CGNAT?

Port forwarding issues, making it harder to run servers or access home networks remotely.
Increased latency and complexity in packet routing.
Troubleshooting difficulties due to obscured IP address paths.
Compatibility issues with some applications like VoIP, P2P, and online gaming.

CGNAT Solutions for Internet Service Providers

To manage CGNAT effectively, ISPs use specialized hardware and software, including:

High-capacity NAT gateways
Monitoring tools to track usage and performance
Security policies to mitigate abuse and hacking attempts
IPv6 transition support for future-proofing

What is NAT444?

NAT444 is a configuration used in CGNAT environments. It involves three layers of NAT:

Customer’s internal network (private IP)
ISP-assigned private IP (from 100.64.0.0/10)
ISP public IP shared across users This setup increases complexity and may introduce latency and compatibility issues.

Why Are Service Providers Switching to IPv6?

IPv6 offers a vast address space (340 undecillion addresses), solving the IPv4 exhaustion issue. Providers are transitioning to IPv6 to:

Future-proof their networks
Reduce reliance on NAT
Improve performance and security
Enable end-to-end connectivity

What is NAT64?

NAT64 is a translation function that enables IPv6-only devices to talk to IPv4 servers. It is implemented in combination with DNS64 and is particularly beneficial during the transition phase towards complete IPv6 deployment.

What Doesn’t Work When Using CGNAT?

A number of services don’t work under CGNAT, including:

Hosting servers at home (HTTP, FTP, game servers)
Peer-to-peer applications such as BitTorrent
VoIP services and certain video conferencing software
Remote desktop software that demands direct IP access

Does CGNAT Impact Online Gaming Performance?

Yes, CGNAT can adversely influence online gaming because of:

Cannot use port forwarding, impacting matchmaking
Increased latency from multiple layers of translation
Disconnections in peer-hosted games. Some players use VPNs or ask for public IPs to alleviate these issues.

Do All ISPs Implement CGNAT?

Not all ISPs employ CGNAT. It is more typical for mobile broadband and smaller ISPs with constrained IPv4 resources. Most large ISPs provide public IP addresses or dual-stack IPv4/IPv6 configurations.

How Do I Get Around CGNAT Using FastestVPN?

FastestVPN enables you to evade CGNAT through the creation of an encrypted connection between your computer and their VPN server. This offers:

A static or public IP (subject to the chosen plan)
Improved privacy and security
Less influence from CGNAT limitations
Access to banned services and improved gaming performance

Conclusion

As you’ve hopefully read the above guide, it’s time to give a full-fledged final version regarding what is CGNAT. It is explained as a Carrier Grade NAT necessary for operating IPv4 functionalities. However, it also has its fair share of downsides. Although it helps ISPs in conversing IP addresses, it also complicates certain activities on the internet for end-users. It is hard to understand the entire working of CGNAT and the ways to bypass it. Still, by using reliable VPNs, such as FastestVPN, and Public IP requests, or IPv6, users can possess full internet access.