Carrier-grade NAT

Uncommon card · No. 84467

Carrier-grade NAT (CGN or CGNAT) (also known as large-scale NAT, LSN) is a type of network address translation (NAT) used by Internet service providers (ISPs) in IPv4 network design. With CGN, end sites, in particular residential networks, are configured with private network addresses that are translated to public IPv4 addresses by middlebox network address translator devices embedded in the network operator's network, permitting the sharing of small pools of public addresses among many end users. This essentially repeats the traditional customer-premises NAT function at the ISP level. Carrier-grade NAT is often used for mitigating IPv4 address exhaustion. One use scenario of CGN has been labeled as NAT444, because some customer connections to Internet services on the public Internet would pass through three different IPv4 addressing domains: the customer's own private network, the carrier's private network and the public Internet. Another CGN scenario is Dual-Stack Lite, in which the...

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