What is the NBN?

Where is the NBN in the Internet?

The NBN or National Broadband Network is a business that is laying new technology connections for Australia's internet.
In the past, the Internet has been connected to businesses and homes by a mixture of old wired technologies.

Using light in a 'fibre optic' cable allows far better performance for the internet and this is the main technology being used by the NBN.

In the past an ISP or Internet Service Provider would provide cable or lease wire phone lines to connect to existing business or home premises.

The NBN now (mostly) owns the connection infrastructure between premises and ISP's.
Rental is then paid to the NBN for ISPs to sell internet services to business and home customers.


Why are there Problems with Internet Connections with NBN?

1. Connection to Premises
The major parts of the NBN internet are connected by very fast fibre optic cable. This is the 'backbone' for traffic between cities and the main internet connections.
For cost reasons, the fibre optic cable is not used, in most cases, to connect from the main backbone to existing business or residences.

The last part of the connection is by a range of technologies even, in some cases, using existing telephone wire connections. This means that the speed of the fast fibre optic cable is restricted by the last part of the connection to your home or business. New developments and buildings should get the high speed fibre-optic cable as part of their construction.

2. ISP Capacity Estimates
Because ISPs are renting infrastructure from the NBN they have also underestimated customer demand and not rented enough capacity, again leading to restrictions on internet performance.

3. Technology Problems
In some instances the NBN has had problems with the sharing of the fibre optic connection between premises over certain types of wired connections, especially the cabled (HFC) areas.

What are the types of Internet Connections with NBN?

The diagram shows some typical connections that are used from the main 'backbone' fibre optic cable to the 'nodes'.
A node is a distribution point that connects many businesses, homes or multi-story residences in an area to the internet.

Some of these will have direct fibre optic cable connections but many will have copper wire connections via existing telephone wires or cables.
In the case of remote rural areas it is not possible to lay a cable all the way so satellite connections are used.


The NBN owns all the infrastructure up to the ISP connection.
The black boxes labelled NBN are the various types of connection boxes that might be used to connect to the premises.
Usually there will be an ISP supplied device (modem) also connected to provide the services to the client. These have not been shown for clarity.

What do the parts look like?

At your residence there will be a connecting box on the outside of the house. This may not be visible if you are in a unit.
A cable will come out of this NBN box to connect with your residence via a modem.

The NBN box in the picture below does not yet have the cable connection to the residence installed.


The cable from the NBN box will come inside your residence and connect to a modem



The modem is the connection through the NBN to your ISP.
From the modem a network cable will run to a router.

Wireless Router


Most ISPs will supply a 'wireless router' which has both wired connections and sends out WiFi signals for wireless connection of devices.
The wireless router in the picture is labelled Optus but these devices are made on contract for any ISP.
All have a similar function; to route the internet signals to wired and wireless devices.
Some will have external aerials for WiFi showing. Others, like that in the picture, have an internal aerial.

All the connections from the modem to the router and router to wired devices will be by network cable.
The network cable provides connections for the 'Ethernet', the technology which is used between internet devices.

Network Cable for Ethernet Connections


These cables look similar to telephone cables but have slightly bigger plugs.
An Ethernet cable is not suitable for connecting telephones.

Umm. but where does the telephone connect?

With an NBN connection, the telephone is connected through the internet using a technology called VOIP (Voice Over Internet Protocol).
The wireless router will have at least one telephone type connection at the rear to allow a suitable telephone to connect to the system.

This means that:

  • the NBN system must be powered for the telephone to work
  • a blackout means no telephone is available unless you have a mobile
  • some old handsets may not work with this type of connection
  • if you have a back-to-base home alarm it may not work with NBN (contact your supplier)

Internet Speed

There is a lot of talk by ISPs about internet speed and the numbers might look big but the speeds are measured in bits per second.

For comparison, measures of device storage (like a mobile phone) is in bytes which are commonly made up of 8 bits.

This all means that a 1 Megabyte file (eg the words for one small book) will take about 8 seconds to transfer on a 1 Mega-bit per second (1Mbps) connection
The speed measurement in Mbps (rather than Megabytes) seems to be a historical artifact related to early computing where byte sizes were not standard.

[Here is the math in case you want the detail:
A 1,000,000 byte file (one Megabyte) on a 1,000,000 bits per second (1Mbps) internet will not take 1,000,000/1,000,000 = 1 second to be transferred. That 1,000,000 byte file is 8 x 1,000,000 = 8,0000,000 bits so will take 8,000,000/1,000,000 = 8 seconds to transfer.]

The internet speed through wired connections to the home has changed over the years:

  • The first 'dial-up' modems were about 128 kbps (ie 128,000 bits per second. This technology took over the telephone line completely to operate)
  • ADSL - internet shared with telephone on telephone lines - 425 kbps (ie 4 times the previous)
  • Cable - internet through special coaxial cable (HFC) - 25-30 Mbps (ie 50 times the previous)
  • FTP - NBN internet, optical Fibre-to-The-Premises - 100 Mbps (ie 4 times the previous, or nearly 800 times the earliest modems)

By comparison, the 4G mobile network can deliver around 20 Mbps but this tends to be more variable than wired connections due to varying network congestion.

Note that the numbers above are download speeds which means the speed of files coming from the internet to your device or home.

Upload speeds are roughly one tenth of the download speeds unless a business connection is used which may pay to have equal upload and download speeds.

Other Internet Connections

The NBN is not a supplier for the mobile phone network which is provided by telecommunications companies as a separate network.
The mobile phone network is however connected to the internet so that mobile phones can get internet information.

Suppliers of public WiFi services have to be connected to the NBN to provide internet services.
These public wifi connections are thus subject to the problems of the NBN.

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