What is CGNAT and How Does it Allow Multiple Mobile Users to Share One IPv4 Address?

In today’s digital landscape, the demand for internet access is higher than ever. However, with the limited supply of IPv4 addresses, carriers are faced with a challenge: how can they connect millions of mobile users with a finite number of IPs? The solution lies in a technology known as Carrier-Grade NAT (CGNAT).

What is CGNAT?

CGNAT, or Carrier-Grade Network Address Translation, allows internet service providers (ISPs) and mobile carriers to assign a single public IPv4 address to multiple users. This is done by assigning each user a private IP address behind the scenes and then translating these into the shared public IPv4 address when communicating with the internet.

How Does CGNAT Work?

CGNAT works by mapping different users’ private IP addresses to different ports on a single public IPv4 address. When a user accesses the internet, their data is tagged with a unique port number, allowing the carrier to route the traffic correctly. This enables multiple users to share the same public IPv4 address without interference.

Why is CGNAT Necessary?

The main reason CGNAT is essential is the shortage of available IPv4 addresses. The rapid growth of mobile users has outpaced the availability of IPv4 addresses. CGNAT extends the lifespan of IPv4 while the world transitions to IPv6, a new protocol with a much larger pool of IP addresses.

Challenges of Blocking Users Behind CGNAT

One significant challenge for websites and services is that it becomes harder to block individual users who are behind a CGNAT setup, such as those using mobile proxies. Since multiple users share the same public IP address, blocking that IP could result in restricting access to many innocent users who have done nothing wrong. This shared nature of IP addresses through CGNAT makes it difficult to determine whether the traffic originates from one user or multiple users. For this reason, many websites avoid blocking mobile IPs, as they risk affecting a large number of legitimate users.

Key Advantages of CGNAT

  1. Efficient Use of IPv4 Addresses: By allowing multiple users to share one IP address, CGNAT helps carriers manage limited IPv4 resources effectively.
  2. Seamless Internet Access: CGNAT ensures that users can continue to access the internet without being affected by the IPv4 shortage.
  3. Enhanced Network Management: Carriers can maintain control over network traffic while supporting a larger number of users.

Conclusion

CGNAT is a crucial technology that helps mobile carriers meet the demand for internet access, despite the limitations of IPv4. By allowing multiple users to share one public IP address, CGNAT ensures efficient network operation and a smooth user experience. However, this shared IP approach also makes it harder for websites to block individual users, as the risk of inadvertently blocking many legitimate users becomes a real concern. CGNAT provides a bridge until IPv6 becomes the global standard, offering a temporary but essential solution to the IPv4 shortage.