Part of demystifying IPv6 was that in practice the most significant 64 bits are the limiting factor. It helped me to put more manageable numbers on things. Ea

Part of demystifying IPv6 was that in practice the most significant 64 bits are the limiting factor. It helped me to put more manageable numbers on things. Each ISP can have 65k customers who are big orgs with complex site needs and a /48, or 4 billion small customers getting a bundle of individual networks on their /56. In the latter, each has address space for, say, 256 VLANs which allows network isolation of many internet enabled fridges. And in theory the current scheme allows for 16 million ISPs to exist, though in practice not all the address space is available.