CGNAT Calculator
Calculate CGNAT public IPv4 address requirements, subscriber port block allocations, and NAT444 capacity for ISPs and WISPs.
Understanding Carrier-Grade NAT (CGNAT) Capacity Planning
Carrier-Grade NAT (CGNAT or NAT444) allows ISPs to share public IPv4 addresses across thousands of broadband subscribers by assigning deterministic or dynamic port blocks (e.g., 1024 or 2048 TCP/UDP ports per subscriber).
Due to IPv4 exhaustion, purchasing public IPv4 blocks costs over $35–$50 per IP. CGNAT reduces public IPv4 requirements by 1:32 or 1:64 ratios while maintaining compliance with law enforcement logging mandates.
Interactive CGNAT Calculator Workspace
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CGNAT Calculator
Supports 8,000 subscribers with deterministic port blocks of 1024 ports.
Real-World Calculation Walkthrough
ISP with 8,000 active fiber subscribers provisioning 1,024 ports per subscriber
Input Parameters
Calculation Output
CGNAT Calculator Engineering FAQs
What is a recommended port block allocation per subscriber?
Most residential broadband ISPs allocate between 1,024 and 2,048 ports per subscriber. Smart TVs, gaming consoles, and mobile devices average 150-300 concurrent NAT sessions.
How does CGNAT impact online gaming and P2P applications?
Deterministic CGNAT with UPnP/PCP (Port Control Protocol) or dedicated static public IP add-ons resolves strict NAT type issues for gamers.
What syslog logging is required for CGNAT legal compliance?
ISPs must log public IP, assigned port range, subscriber internal IP, and allocation timestamp to respond to subpoena requests from law enforcement.
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