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NBN explained

Posted by Walter Olson on Jan 13, 2021 11:13:30 AM

Since the advent of NBN, there have been a lot of questions regarding the different NBN Offerings. There are a lot of NBN terms being thrown about, and as such, a lot of confusion. Let’s dispel that confusion. There are 3 NBN offerings; (TC4), which is predominantly used for SMB and residential customers; (TC2), which is a dedicated ethernet connection; and Enterprise Ethernet, which is more focused at larger customers with a higher class of service.

Ok, that is nice, but what does that mean?

Let us break it down across the different types.


You can get NBN TC4 through a number of technologies: Fibre to the Premises (FTTP), Fibre to the Basement (FTTB), Fibre to the Node (FTTN), Fibre to the Curb (FTTC), Hybrid Fibre Coaxial (HFC), Fixed Wireless (FW) and Sky Muster Satellite Options. Depending on the technology, you can theoretically get download speeds ranging from 25Mbit per second up to 100Mbit per second, and upload speeds of 5Mbit per second up to 40Mbit per second.

NBN TC4 is asymmetrical, which means that you shall get faster download speeds than upload speeds. Furthermore, TC4 is best effort Peak Information Rate Services (which means if you have a lot of people on the network, and your provider hasn’t provisioned enough CVC, there will be contention on the network, as all the connections in your local area on NBN with the same provider shall be funnelled through the same “port”).

You may be reading this and think, well, my customers run businesses, and this is residential grade. Not entirely true. There are many good reasons to consider customers with less than 50 users to use NBN TC4. One of the main factors is how much CVC (Connectivity Virtual Circuit) is provided by connection and how much capacity has been allowed for in the NNI (Network to Network Interface) which then connects to the NBN Backbone. Furthermore, the cost of the NBN TC4 service is much more appealing to SMB customers than TC2 and Enterprise Ethernet. It really comes down to the network that the NBN Tails (Yep, another new one for you. It means physical connections on the customer premises) is sitting on and how well that is managed.


NBN TC2 is the next solution up the stack. This is more for SME and larger businesses that need symmetrical services with a Committed Information Rate based service. These services are generally providing speeds dependant on connection between 5Mbit per second to 20Mbit per second. The benefit of these services is that they have CIR, which in theory, means that the bandwidth should not fall below this CIR.

NBN TC2 is available only on certain number of technologies. Fibre to the Premises (FTTP), Fibre to the Node (FTTN), Fibre to the Basement (FTTB), and Fibre to the Curb (FTTC).

If you have gotten this far, it seems you are interested in reading on, so let’s get to Enterprise Ethernet.

NBN Enterprise Ethernet

For NBN Enterprise Ethernet, the site needs to have dedicated infrastructure, and there may be a build component, which can be in excess of $5,000. The services are Symmetrical and is Class of Service (COS) based with a mix of CIR and best effort Excess Information Rate components (EIR). EIR is an allowance of burstable bandwidth.

The symmetrical speeds range between 10Mbits per second and 1Gbit per second. As such, this is really focused on larger organisations. Now, to add a little bit of complexity to this (why make it easy? We are in IT!), there are effectively 3 different traffic classes. High QoS (100% CIR), Medium QoS (25% CIR | 75% EIR) and Low QoS (100% EIR), and NBN have zoned connections between CBD, Zone 1, Zone 2, and Zone 3. The further you get away from the CBD Zoning, the more your Monthly Reoccurring Cost (MRC – there is another term for you) shall be.


If you got through all the acronyms and you understand it all, my hat comes off to you dear madam or sir. Otherwise, give Iperium a call and we can work through the above in more detail and give you advice on what is the best solution for you and your customers moving forward.


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For more information, call us on 1300 592 330 and one of the team will be happy to assist.

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Topics: NBN, Channel Partner

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