As the demand for internet connectivity grows, the available pool of IPv4 addresses is rapidly depleting. Carrier-Grade Network Address Translation (CGNAT) technology is being increasingly adopted to address this issue. CGNAT provides a practical and cost-effective solution for ISPs to manage this challenge, enabling them to continue serving their growing customer base without a complete transition to IPv6. Before deploying and implementing a CGNAT solution, let’s review some CGNAT best practices.
CGNAT Deployment Strategies
ISPs have a range of strategies for deploying CGNAT within their networks. One particularly flexible and empowering approach is the phased deployment of CGNAT. This strategy allows ISPs to gradually transition customers from public IP address assignments to the shared CGNAT environment at a pace that suits their specific network and customer base.
“Dual-Stack” is another strategy for dealing with the incompatibility of IPv4 and IPv6. According to Google, only 43% of websites currently support IPv6. This means the majority of websites still use IPv4. Dual-stack technology enables service providers to configure every networking device with both IPv4 and IPv6 connectivity capabilities, allowing them to process IPv4 and IPv6 traffic at the same time.
Some ISPs may also implement a hybrid approach, maintaining a pool of public IPv4 addresses for specific high-priority customers or applications while using CGNAT for most of their customer base.
CGNAT Best Practices
To ensure the successful implementation and operation of CGNAT, ISPs should follow a set of best practices. One key best practice is carefully planning and designing the CGNAT deployment, considering the expected number of customers, the anticipated growth in internet-connected devices, and the network’s specific requirements.
Another best practice is implementing robust monitoring and troubleshooting tools to maintain visibility into the CGNAT environment. These tools can include techniques such as monitoring session use for your most active subscribers, monitoring for session exhaustion, and monitoring overall concurrent session consumption.
It’s also crucial for ISPs to monitor customer support calls for any issues related to the initial CGNAT implementation. CGNAT should be completely transparent to users, but older applications may need “Application Layer Gateways (ALGs)” enabled in the CGNAT configuration. ALGs are software components that provide translation services for certain applications or protocols. Typical applications that may require ALGs include FTP, early-generation SIP, and old PPTP VPNs. Any issues with these point to the need to enable those ALGs.
Since public IPv4 addresses are limited in availability and expensive, ISPs should still support their use but reserve them for business customers and premium residential plans. You should also consider allowing power users to have a plan (at a higher price) that comes with a non-NAT address.
CGNAT and IPv6 Transition
As the internet landscape evolves, the transition to IPv6 has become a critical priority for many ISPs and network operators. CGNAT plays a vital role in this transition by helping to extend the life of IPv4 address space. This reassures ISPs that they can focus on deploying IPv6, knowing that CGNAT supports the transition.
By implementing CGNAT, ISPs can continue to serve their existing IPv4-based customers while gradually transitioning their network infrastructure to support IPv6. This can help alleviate the pressure to migrate all customers to IPv6 immediately, which can be a complex and resource-intensive process. When implementing dual-stack, most service providers will see 40% to 60% of their overall traffic move immediately to IPv6.
A CGNAT for Local and Regional ISPs
Most legacy CGNAT vendors offer CGNAT software bundled with proprietary hardware. While these CGNAT products have features desired by large Tier One carriers, they also come with expensive price tags.
netElastic CGNAT was designed for local and regional ISPs who want the essential CGNAT features at a fraction of the cost of traditional CGNAT products. By choosing netElastic, ISPs can be cautious and resourceful, making the most of their budget while still getting the most important CGNAT features.
To learn more, please read the HighStream Fiber CGNAT case study.