Best practice for an ISP that is implementing CGNAT is to use 100.64.0.0/10 as per RFC 6598. That way, your customers can use private IPv4 (10/8, 172.16/12, 192

Best practice for an ISP that is implementing CGNAT is to use 100.64.0.0/10 as per RFC 6598. That way, your customers can use private IPv4 (10/8, 172.16/12, 192.168/16) and you can manage your ISP network in the 100.64.0.0/10 space. Your CGNAT looks after translating your customer's ISP address (ie, the 100.64.0.0/10 side of their CPE). Of course, the best solution is to move to IPv6 and allocate each customer: * a /64 address out of the ISP's network space * a /48 (or /56) delegation for their own network See https://www.ripe.net/publications/docs/ripe-690 https://www.ripe.net/publications/docs/ripe-690