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Getting the balance right on building the nbn™ network

nbn is building the network in the most cost efficient manner possible, making the best possible use of taxpayer dollars…

Building a broadband network like the nbn™ network is a huge challenge for many reasons and one of the most important is getting the balance right in terms of where we invest taxpayer money – we need to make sure every dollar is invested wisely.

That means that in an environment where broadband usage is always increasing we not only need to make sure we build a network that can handle all the traffic on it – especially all that video content people are now watching – but we also need to be careful not to over invest and have far more capacity than we actually need.

If we invest in capacity that is not going to be required for some time then that is arguably a waste of money and we could and should have been spending those dollars somewhere else on the network where they could have been more productively spent.

The Backhaul Conundrum

One area where we have to get this balancing act right is on backhaul – that means how we carry traffic from our Wireless Base Stations, our Fibre-to-the-Premise (FTTP) Optical Terminals or Fibre-to-the-Node (FTTN) street cabinets back to the Point of Interconnection (POI) which is normally located in a telephone exchange.

The Wireless Base Stations, FTTP Optical Terminals and FTTN cabinets serve vastly different numbers of people, our largest FTTP Optical Terminal serves around 3,000 premises and has 10Gbps of backhaul available – but the reality is that we are usually only using around 15% of that capacity at the moment.

By contrast an FTTN cabinet will serve only around 384 premises so we don’t need anything like the same amount of capacity as we do for an FTTP Optical Terminal.

In areas where the nbn™ Transit Network is available we could provide all the way up to 20Gbps backhaul for an FTTN cabinet if we chose to do so – but it’s highly unlikely that we will need that amount of backhaul capacity for an FTTN cabinet for quite some time.

The reality is that we can quite easily upgrade our FTTN cabinet backhaul capacity whenever we need to do so by simply installing a new optical interface – there is no need whatsoever to run any new fibre.

We are building a network that we can upgrade in an efficient manner and we are making investments in the right amount of capacity at the right time.

A moving landscape

The other complicating factor that we have is that in some parts of the nbn™ network we currently have to lease backhaul capacity from private sector operators.

When we do this we have to pay on the basis of a peak bitrate required – this means we have to be very prudent in working out exactly how much demand will be required or face the prospect of paying a lot of money for capacity that we did not actually need.

To make sure we do this properly we continuously monitor our traffic levels and we increase our capacity when we need to do so to help us maintain our quality of service – but we make that investment only when it is required.

Our primary goal is to deliver quality services to our end-users and when we need to acquire extra capacity to do that we do so.

Understanding Internet traffic

Our team at nbn has many years of experience in designing and building broadband networks – so we understand consumption is increasing and we know how to plan for and deal with that.

With this in mind it’s also very important to understand exactly how that consumption is going to occur – not everybody is going to be streaming Netflix video content at exactly the same time, the demand will be spread over the day – which is crucial to understand when planning capacity.

In addition, it’s worth remembering that when it comes to streaming video like Netflix that end-users are not all synchronised in their viewing – this means that they are not going to be hitting the backhaul link simultaneously so you are unlikely to have capacity issues even at peak usage times.


Tony Cross is Chief Architect at nbn.

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