One of the less-discussed points about the joy of muni-fibre, and for that matter commercial FTTH, is what happens in the next hop. At the moment, the last mile is the slowest hop, in terms of data rate. The backbone is usually considered to be OK, thanks to the dark fibre phenomenon, technical improvements such as DWDM, and the fact it's easier to lay more fibre in one dig next to the highway than ten thousand digs in the city centre. Especially in L2TP/bitstream markets, the sector from the aggregation point to the ISP's gateway router is more of a problem, but this is usually a matter of ex-incumbent pricing rather than a real shortage.

But if the access network gets replaced by fibre, what then? ISP engineers deal daily in interconnects up to Gigabit Ethernet, but if 40Gbits Granny's in town, there's going to be a quantum leap in demand at the next hop after the fibre access ring. In fact, it's worse than that; Granny is a special case, but a town's worth of 100Mbits/s Mums means you'll rapidly reach genuinely huge demands on the pipe out to the backbone. For that matter, you wouldn't need that many to strain your friendly local IX.

That's the sort of thing you have to think about when you're sitting next to Ad Ketelaars of Eindhoven's munifibre deployment, while Chris Schoettle of Akamai is presenting. Shoettle, unsurprisingly, thinks CDNs are great, and so do we; but there's better than that. He makes an important point about distance and speed - quite simply, going from less than 100 to 500-1000 miles' worth of speed-of-light latency means that a file you could be pulling down at 44Mbits/s (if you have fibre) instead arrives around 4Mbits/s. If you're constrained by the local loop, you're unlikely to notice the difference; once the speeds go up, though, you certainly will.

No wonder, then, that Eindhoven is keen to get not just CDN capacity in their backyard, but another IX somewhere in southern Holland or Belgium to take some of the load off AMS-IX. Screaming-fast local loops will force us to invest in content-delivery networking and related problems.