The responses of Internet Service Providers (ISPs) to lack of IPv4 address space range from outright denial (sometimes coupled with reassuringly-expensive large-scale carrier-grade NAT) to all-in IPv6-only designs using 464XLAT for residual IPv4 connectivity.

To understand the implications of these extremes and a few data points between them, watch the ISP IPv6 Transition Strategies video from Enterprise IPv6 – the First Steps webinar.