nbn has generated more than its fair share of headlines since being created eight years ago and Australians are probably more knowledgeable than any other nation about the merits of various broadband access technologies, given the intense coverage the nbn™ network has received.

However, while regular Aussies may now be familiar with the Fibre-to-the-Premises, Fibre-to-the-Node and Fixed-Wireless network technologies, they are probably not aware one of our most important networks, the nbn™ Transit Network, even exists!

While debate has raged around nbn™ network deployment, nbn has been plugging away lighting up the 60,000 kilometres of fibre-optic cabling that makes up the nbn™ Transit Network and that links together our 121 Points of Interconnect (POIs).

nbn uses the Transit Network to send our own data to the 121 POIs – including things like orders for new services – which should increase substantially as we move towards the planned 8 million connected homes and businesses by 2020. The nbn™ Transit Network also sends our data back to our two nbn data centres.

However, the Transit Network is also connected to our local Fibre Access Nodes (FANs), which carry traffic to end-user premises, meaning that nbn needs to make sure we are able to provide plenty of capacity to carry that traffic.

The best is yet to come

Although we are proud of what we have achieved with the nbn™ Transit Network, we are not finished yet. We know the network will need to carry more and more capacity in the years ahead as new bandwidth-intensive applications arrive into the market.

This is why we are planning on doubling the capacity of our Transit Network by installing new technology from our technology vendor Coriant with the network upgrade being gradually carried out from next year onwards, with initial upgrades being carried out in Sydney and Melbourne.

The upgrade means that our Transit Network, which utilises Dense Wavelength Division Multiplexing (DWDM) that puts data from different sources together with each signal carried at the same time on its own separate light wavelength, should be able to deliver per-wavelength transmission speeds of up to 200Gbps and beyond.

No new digging!  

To be absolutely clear, nbn doesn’t have to go back and lay new bigger cables to double our Transit Network capacity; this upgrade is carried out simply by installing new electronics on the existing network that give us greater capacity and higher transmission speeds.

In addition, because we are planning on doubling the capacity of the nbn™ Transit Network in a cost-effective manner – the new technology is also designed to be more power and space efficient – we expect to actually reduce our cost of transmitting data on a per-bit basis.

So, while we accept that our Transit Network is never going to grab the media limelight in the way that our higher profile customer access networks do, we are very proud of the work we have done in building the network and know it plays a crucial role in helping to deliver a great nbn experience to Australians.

Grant Bowden is Executive General Manager Engineering at nbn.