Hybrid Fibre Coaxial
In the 1990s, Optus and Telstra began rollouts of cable technology using a Hybrid Fibre Coaxial (HFC) network. These networks were considered the first broadband networks, and the available bandwidth enabled high speed internet access (up to 30 Mbps) and multiple pay TV channels down a single coaxial cable.
Unfortunately due to the competitive nature of the market, the two companies followed each other around so that you either had both networks available to you, or none. If you didn’t have HFC passing outside your home, you were stuck on dial-up.
At some point, Optus stopped rolling out their network, so Telstra then stopped rolling out theirs too.
Asymmetric Digital Subscriber Line
Asymmetric Digital Subscriber Line (ADSL) has been around since the turn of the century. Originally rolled out by Telstra, it uses filters to divide a single telephone line into two channels. This enables simultaneous high speed broadband access and telephone calls.
Prior to ADSL, landline telephones were more commonly used as mobile saturation was low. With more and more people using dial up internet, this would tie up phone lines and people could not be reached by telephone when they were on the net.
ADSL Technology Types
ADSL was originally offered at three different speed tiers. 256/64 kbps, 512/128 kbps and 1536/256 kbps. Telstra did not offer speeds greater that 1536kbps so that each line, no matter how long, would be able to achieve the advertised line speed.
ADSL2 and ADSL2+
As time went by, improvements in ADSL protocols and opening up of Telstra lines to competitors saw ADSL2 (max 12 Mbps) and ADSL2+ (max 24 Mbps) become available around the country. These higher theoretical speeds were however affected by line length and quality and most subscribers would not achieve the theoretical maximum.
National Broadband Network (nbn)
In 2007 the Rudd government proposed to build a national broadband network to provide equal, unbiased access to all suppliers. Initially it was planned to build a Fibre to the Node (FTTN) network, with satellite used in regional and remote areas where FTTN was not economical to roll out. An FTTN network would require a deal to be made with Telstra to access their copper lines for the last mile (node to subscriber).
nbn Version 2
After some problems with the Telstra management at the time, failed tenders and capital raising the plan was revised in 2009 to bypass the Telstra network completely with a full Fibre to the Premsies (FTTP) network, and fixed wireless or satelite for regional and remote areas.
nbn Version 3
With the 2013 election of the Abbott government, a change to the access technologies was announced. Any areas that were currently being built with FTTP were allowed to be completed, but areas not yet started were revised to try and reduce the cost of, and the time to complete the rollout.
The government would now utilise Fibre to the Node (FTTN) technology, interfacing with the existing Telstra copper network (now made possible by a new, more receptive Telstra management team). Also, in areas that already had it, nbn would utilise existing Hybrid Fibre Coaxial (HFC) networks originally rolled out in the 90s for pay TV and broadband.
With FTTN, not enough consideration to the length and quality of the copper loops was given and some subscribers ended up on long lines of copper which reduced the achievable speeds considerably.
Similarly with HFC, not enough consideration was given to the state of the network, and the fault rate was unacceptably high, prompting a pause on the HFC rollout while significant upgrades were undertaken before the HFC rollout resumed.
In 2014, TPG started to roll out their own Fibre to the Building (FTTB) network to residential buildings in the capital cities. This prompted nbn to bring forward their FTTB rollout in fear of losing market share.
Fibre to the Curb (FTTC) started to be rolled out in 2018 to try and improve achievable speeds without building a complete fibre network.
nbn Technology Types
Depending on where you live, nbn has (or will be) implementing access technology for internet providers to supply broadband to consumers. Ultimately, nbn choose the technology type for each given area.
Fibre to the Premises (FTTP)
FTTP connections have fibre all the way to the NBN network termination device installed at your premises. This was the original model the nbn was based on before a change in government in 2013.
Fibre to the Node (FTTN)
FTTN connections have fibre up to the local Telstra pillar (or closer if served by a micronode), then your service is delivered over the existing Telstra copper lines. Speed degradation occurs over the copper section of the circuit. The longer the copper, the lower the maximum speed that can be achieved.
Data on copper length is not available to us until after a service is active. Once your modem is in sync, the copper length can be estimated.
The copper lines within your premises can also cause significant speed degradation, especially if there are more than one telephone sockets (even though you only use one).
Fibre to the Building (FTTB)
FTTB connections are found in multi dwelling units such as apartment blocks and shopping centres. The fibre is extended up to some nbn equipment installed at or near the communications MDF of your building. From there it uses the copper pairs to each living unit or individual premise.
The copper component of these connections is usually very short, within a few hundred metres. Usually if the copper is no more than 300m, modems can achieve a full rate sync of 100/40.
Hybrid Fibre Coaxial (HFC)
HFC connections use the Telstra / Foxtel pay TV cabling installed during the 1990s. They are the original fibre to the node connections as there is fibre up to the optical node, and then it uses copper (coaxial) cabling to each wall plate within each premises.
The copper connection is superior to twisted pair used in technologies above as coaxial has greater bandwidth (1GHz), and it is amplified along the way, so attenuation is not an issue. However, it is a shared medium (all the packets travel along one circuit for all users) so congestion can occur in the copper part of the circuit, impacting on speed.
Fibre to the Curb (FTTC)
FTTC is the latest and greatest technology introduced by nbn. Fibre is installed right up to the Telstra pit outside the premises. A distribution point unit (DPU) is installed and connected to the existing copper lead-in cable going into each premise. The copper component of the circuit is very short (less than 150m) so all currently offered bit rates are achievable at least up to the building entry point. However, as with FTTN, the copper lines within your premises can also cause significant speed degradation, especially if there are more than one telephone sockets (even though you only use one).
The DPU requires power but as power cannot be transmitted over optical fibre, nbn will supply a network connection device (NCD) which will plug in inside the end user premises and back feed power along the copper lead-in out to the DPU.