How We Built One of Europe's First Large-Scale MAP-T Deployments on RDK-B

The Problem: IPv4 Exhaustion at ISP Scale By late 2019, IPv4 address exhaustion had moved from a theoretical concern to an operational reality. On 25 November 2019, RIPE NCC — the regional internet registry for Europe — made its final IPv4 allocation, officially running out of addresses entirely. For an ISP like SKY UK, serving millions of broadband subscribers across the UK and Italy, this created a concrete engineering challenge: how do you keep growing your subscriber base when you cannot acquire new IPv4 addresses at reasonable cost? The long-term answer is IPv6. But the internet in 2019 was still overwhelmingly IPv4 — content providers, gaming platforms, and enterprise services all expected IPv4 reachability. A pure IPv6 deployment would break everything for customers overnight. ISPs needed a transition mechanism — a way to run a pure IPv6 core network while still delivering working IPv4 connectivity to every subscriber. Several approaches existed: DS-Lite — tunnels IPv4 over IPv6