Hello Ana
Technologically, carrier-grade NAT (CGNAT) and regular NAT function the same way. The differences between CGNAT and regular NAT have to do with the way they are implemented as well as with the scale of implementation.
CGNAT is an approach to IPv4 network design that simply moves the location of NAT from the edge of the enterprise to somewhere within the ISP’s network. In this way, an ISP can provide NAT services centrally for all of its customers rather than employing NAT at each individual customer. In essence, this simply shifts the NAT function and configuration from the customer premises to the ISP network.
The implementation of CGNAT requires that the ISP design their network accordingly. CGNAT requires NAT routers that are specially designed to handle the large volume of NAT translations that would result from such a design. Also, ISPs will have to provide private IP addresses to their customers and any port forwarding or static translations would have to be managed by the ISP based on the requirements of each customer.
The implementation of CGNAT primarily affects network design principles and not technological implementation methods.
This depends on the definition that the ISP places on that statement. I would assume that if you don’t want to use the ISP’s CGNAT, they should then give you connectivity where you can perform your own NAT at the network edge, and be provided with a public IPv4 address.
I hope this has been helpful!
Laz