Why? — The case for fibre to the premises

It's not complicated

This is what a FTTP connection looks like, when Telstra are the contractors.

Adds value

Fibre to the premises is known to create interest in properties, and has been estimated to add $5,000 to greenfield builds. Surveys of purchasers indicate they will pay $10,000 for reliable NBN access, but the actual value added by FTTP as opposed to FTTN is endlessly debatable.

$10,000 is a reasonable premium for FTTP, because the individual cost to post-upgrade a single premises to fibre has averaged $22,368. A FTTP-desiring buyer would factor that into their valuation.

The nbnm8 browser plugin shows the NBN status of properties when searching real estate.

Works when wet

FTTP cabinets contain simple "plug panels", and fibre is OK with water ingress. Copper is known to be less reliable when wet, and FTTN cabinets ("nodes") which contain fans and batteries will fail in floods.

The FTTN design for WEPN20 has not been published, but the presence of a copper junction at Parkridge Place could see the NBN standing a node there, exposing it to an actual flood hazard. FTTN nodes are plugged into mains power and its underground copper cables are subject to corrosion.

In comparison, FTTP needs fewer cabinets as they service more properties, are physically smaller and contain no electrics. Fibre network are expected to last 100 years.

It can only get faster

Faster internet is important because the coming economy will rely on it.

Data speed is measured in Mb/s (megabits per second). For example, a good quality "4K" movie needs about 50 Mb/s to watch over the internet.

Fibre (FTTP)

Fibre optic cable has been demonstrated to carry data at 101,700,000 Mb/s (101.7 Tb/s) at a distance of 165 km.

But hold on, NBN fibre will not initially be that fast. That's because the practical speed limit of fibre depends on the transceiver technology installed at each end. While the fibre itself has virtually unlimited capacity, the transceivers still have to do a lot of work.

NBNCo is currently deploying GPON transceivers capable of 2,488 Mb/s over a distance of 20 km including a 32-way optical splitter. Upgraded transceivers will provide 40,000 Mb/s to customers with just a module swap. Like modems in the 1990s, fibre transceivers are currently getting faster and cheaper.

A 2,500 Mb/s GPON transceiver. About the size of a tube of toothpaste, you can pick one of these up on ebay from around $50.
One side contains the laser, the other side the receiver. It's marked with little in/out arrows.

Copper (FTTN)

Copper cables are sensitive to electrical noise, and the best transceivers (modems) are limited by regulation in their transmit power. The speed limit of copper depends mainly on the cable length.

At short distances of 50 m, eight-wire ethernet cable can carry 10,000 Mb/s. This is why ethernet computer cables contain wire: it's great for short distances.

Suburb scale is another matter. The best-known signalling technique over two-wire phone lines, VDSL2, has been measured under laboratory conditions to carry 50 Mb/s to a distance of 1 km. But, many houses have a redundant or spare phone pair available, so this can theoretically be doubled to 100 Mb/s.

The FTTN plan is compromised

Previously, many households used ADSL for internet. This involved residents installing an ADSL modem in their home, and internet providers like Telstra or TPG would install a bank of ADSL modems in the local telephone exchange. The modems would push data over distances of 50 m to 6 km, corresponding to speeds of 50 Mb/s down to 1 Mb/s.

In 2014, the NBN was directed to stop rolling out FTTP fibre, and start installing FTTN nodes. This plan involves residents installing VDSL modems in their homes, and the NBN would install a bank of VDSL modems in a node cabinet next to each dome-topped Telstra pillar. The pillar would be wired to the cabinet, and the cabinet would be connected to the telephone with new fibre. It would arrive a year sooner, and be 10–30% cheaper.

Meanwhile, the VDSL modems would push data over shorter distances of 50 m to 2 km, corresponding to speeds of 50 Mb/s down to 12 Mb/s. On average, only 25 Mb/s could be confidently claimed.

In 2015, to achieve an average minimum speed of 50 Mb/s, the FTTN design now stands more nodes to reduce the average copper run to a house to 450 m.

The current FTTN now requires pulling fibre down residental streets to the secondary nodes, which uses less of the original existing copper, and requires time-consuming cutting into unmarked copper bundles. This raises build and operational costs, and lengthens build times to be comparable to FTTP.

The costs are passed on as higher "CVC" prices which squeeze the RSPs into oversubscribing, meaning everybody sees more congestion on the NBN.

Blue copper oxide "rust" inside a telephone wall socket. Copper corrosion underground causes mild electrical shorts that degrade communications.

Fibre continues to get faster

At a generous FTTN distance of 1 km, we've seen that copper can carry 1,000 Mb/s (under ideal conditions). Fibre has been shown to carry upwards of 100,000,000 Mb/s at further distances. It's clear that fibre media is 100,000 times faster than copper.

Today, in a practical short-term sense, the 2,500 Mb/s GPON fibre and 50 Mb/s VDSL2 copper NBN offerings, makes today's fibre look only 50 times faster.

However, the future of an all-fibre install has a much, much brighter potential because fibre transceiver technology continues to evolve. In comparison, the limits of copper have been well and truly reached: all of copper's future costs will be in maintenance.

NBNCo recognises the demand transition towards higher bandwidths. It is "constantly looking at reducing" the number of houses on FTTN.

Think back...10 or so years ago, when dial-up speeds were "just fine" for most everyone,
what caused that to stop being "just fine"?

A 100,000 Mb/s fibre transceiver. They've come down in price to around $350 now and continue to fall.

Fibre is fairer

Because copper's speed depends greatly on distance, homes furthest from a node or exchange will always miss out on the top speeds available to those virtually adjacent. For example, maximum 25 Mb/s versus 1000 Mb/s.

This makes public-provided urban infrastructure using any copper-based network design unfair as it trades away equal-access for build costs even though those costs are spread evenly over subscribers.

At suburban scales, fibre's speed is only limited by the transceiver technology used, not the cable length. When infrastructure costs are shared, fibre provides everyone with access to the same speeds.

Global context

China

"Broadband China" is China's equivalent to the NBN. Started in 2013, their stated objective was to bring 100 Mb/s to all households at prefecture level, and at least 30 Mb/s to 80% of villages. Xinhua reports investment has been extended to reach 90% of countryside, so as to develop the new economy and foster growth momentum.

Over 90% of Broadband China connections are FTTP or FTTB. Even if this were purely a social control project, the economic reasoning and long-term planning behind the government's choices of delivery technology seems to be sound.