Carrier-grade Network Address Translation

Carrier-grade Network Address Translation (CGNAT) is an IP address provisioning method using a private IP address block used by Internet Service Providers due to the declining availability of public IPv4 addresses. As of 2020, PLDT has been transitioning both DSL and Fibr customers to CGNAT through modem/ONU firmware updates for existing users. New customers are automatically put under CGNAT. Additionally, service requests involving the resetting of the modem/ONU will also put the customer under CGNAT.

While irrelevant to normal consumers, this kind of IP address provisioning presents serious problems to services (such as hosting, remote CCTV, or games) reliant on port forwarding.

PLDT rivals Globe Telecom and Converge ICT extensively use CGNAT.

However, simultaneous to the CGNAT transition, half of PLDT's customers (as of 2020) have began to get IPv6 addresses which eliminate the need for private addressing and NAT. However, contemporary games and other services or cheaper devices are still reliant on IPv4 and thus, CGNAT will continue to disrupt them.

How it works
Think of CGNAT as your consumer router. When you connect, it gives you a private IP address block (e.g. 192.168.X.X, 10.X.X.X, 172.16.X.X).

For consumers using the modem/ONU provided, our router usually gives us an IP block of 192.168.0.X where X is a number from 2 to 254, depending on the configuration.

For CGNAT, it uses 100.x.x.x (e.g. 100.64.X.X, 100.84.X.X) and cannot be seen outside the network.

Solutions
For those on a residential subscriber line, the following are solutions for those facing issues with their applications or devices:


 * Call 171 and request to be removed from CGNAT
 * This will take multiple calls until you find a L1 technician who knows what CGNAT is. In fact, some of them think CGNAT is a separate ISP that is a competitor to PLDT.
 * Wait until or hope that PLDT implements RFC 6887 .
 * RFC 6887 or the Port Control Protocol (PCP) establishes connections between the modem/ONU and CGNAT servers to implement and support point-to-point (P2P) applications (hosting, remote CCTV, or games) between customers accessing different CGNAT'd devices.