FullFibre did not roll out CGNAT to win an internet argument. It rolled it out because three inherited ISP environments had to be made to behave like one network without burning more IPv4, more rack space, and more time than necessary. That is a much more useful story than the usual CGNAT theology seminar.
FullFibre Turned CGNAT Into an IPv4 Efficiency Tool
netElastic says FullFibre scaled to support more than 140,000 subscribers after consolidating Zzoomm, Digital Infrastructure / BeFibre, and FullFibre onto an integrated BNG and CGNAT software stack running on standard x86 servers. The significance is not that CGNAT exists. The significance is that broadband operators are now using it as a consolidation instrument to squeeze waste out of mixed IP plans and mixed vendor estates.
That is where the IPv4 market quietly enters the room. When address blocks can be bought, leased, or held as assets, inefficient utilization stops being a technical annoyance and starts looking like bad inventory discipline.
Network Consolidation Exposes Every Sloppy Edge Decision
Post-merger broadband integration has a talent for exposing things management decks call synergies and engineers call avoidable headaches. FullFibre’s case study points to one of the cleaner examples: a legacy design where BNG and CGNAT lived separately, versus a new one-box approach that combined the functions and tightened the operational surface.
The sharper detail is DHCP. FullFibre cut lease times from 1 hour to 5 minutes, which meant lost connectivity could be detected and renegotiated much faster during subscriber recovery. That is not glamorous, but neither is spending all week explaining why a merged access network behaves like three networks taped together.
Returning IPv4 Blocks Is the Real KPI
The headline claim that matters most is the expectation of 40% savings over 3 years by returning excess IPv4 blocks once CGNAT is in place. That reframes the whole conversation. The old debate asked whether CGNAT was philosophically pure enough for the internet. The 2026 version asks whether operators can use it to avoid unnecessary address purchases, clean up inherited sprawl, and make consolidation less expensive.
That is also why software-based edge design is getting more attention. If the platform can reduce physical footprint and make address consumption more disciplined at the same time, it becomes part of capital planning, not just subscriber plumbing. For operators trying to rationalize network infrastructure after M&A, that is a very different budget conversation.
IPv6 Progress Does Not Remove the Ops Work
Google traffic crossing 50.10% IPv6 is a real milestone, but mixed-protocol broadband is still the lived reality. Operators are not choosing between a pure IPv6 future and a pure IPv4 past. They are running compatibility layers, inherited customer environments, and edge platforms that still need to handle the stubborn parts of the public internet without wasting scarce address space.
That makes FullFibre’s result more interesting than another anti-CGNAT complaint thread. The company says the new design will halve rack space and power while the combined network passes 600,000 premises. In other words, the next IPv4 efficiency battle looks less like ideology and more like operations: shorter leases, fewer boxes, tighter allocation, and fewer excuses.
FAQ
Why Does FullFibre’s CGNAT Upgrade Matter?
Because it frames CGNAT as an operational tool for ISP consolidation, not merely a workaround for address exhaustion.
What Was the Main IPv4 Efficiency Gain?
FullFibre expects to return excess IPv4 blocks, which turns better address utilization into a direct financial and planning benefit.
How Did DHCP Changes Affect the Network?
Shorter lease timing improved how quickly lost sessions could be detected and renegotiated, which helps during migrations and troubleshooting.
Does IPv6 Adoption Make CGNAT Less Relevant?
No. IPv6 adoption is advancing, but broadband operators still need an efficient IPv4 compatibility layer for mixed customer and application environments.
