What is CG‐NAT (Carrier‐grade network address translation)?

Carrier-Grade Network Address Translation (CGN) is NAT that converts private IPv4 addresses into public IPv4 addresses. CGN utilizes Network Address and Port Translation techniques to aggregate different private IPv4 addresses into less public IPv4 addresses. CGN does not assist integration with Cisco Performance Routing (PfR). This permits ISPs to safeguard their own public IPv4 addresses, process subscriber traffic through the service provider’s private IPv4 network, and assist subscribers that likewise have their own private IPv4 networks and various devices.