The National Broadband Network (NBN) company has announced that it will be replacing the Optus hybrid fibre-coaxial (HFC) footprint with its fibre-to-the-distribution-point (FttDP) network, with up to 700,000 premises to be covered by the new network technology.

FttDP will also be deployed in some areas previously slated to receive fibre-to-the-node (FttN) network connections.

"We have tested FttDP over the last year and we're confident we can now deploy the technology in areas where it makes better sense from a customer experience, deployment efficiency, and cost perspective," NBN chief network engineering officer Peter Ryan said.

"This includes premises in the FttN footprint that have too high a cost per premises (CPP) and premises served solely by the legacy Optus HFC footprint that are yet to be made ready for service."

NBN has been trialling FttDP across Sydney and Melbourne since April, previously saying that it would look at launching FttDP services in 2018 for "several hundred thousand" premises. In October last year, NBN signalled its intent to deploy FttDP for premises that are located more than 1 kilometre from a node.

NBN said on Wednesday that deploying FttDP was more "compelling" than facing the challenge of connecting Optus' HFC network.

"HFC remains a highly valued part of our MTM deployment; however, in balancing the requirements to convert Optus' current network architecture and design to be NBN-ready, and the opportunity to introduce FttDP, makes the new technology compelling in these selected areas," Ryan explained.

The entirety of Optus' HFC footprint, apart from the already activated 18,800 premises in Redcliffe, will be moved to FttDP.

The news of replacing the Optus HFC footprint follows a leaked NBN draft in November last year, which revealed that Optus' HFC network is "not fully fit for purpose", with 470,000 premises in the footprint needing to be overbuilt by either Telstra HFC or fibre services.

NBN's 2017 Corporate Plan subsequently revealed a significantly reduced HFC footprint; under the old plan, 34 percent of Australian premises were slated to receive an HFC connection, while 38 percent would be covered by FttN, fibre to the basement (FttB), or FttDP.

Under the new plan, however, this has been changed to between 43 and 54 percent being covered by FttN/B/DP, and between 21 to 27 percent by HFC.

These updated numbers revealed NBN's decision to replace up to 13 percent of Australian premises that were slated to receive HFC with FttN/B/DP, with CTO Dennis Steiger calling the process "reallocation" due to having more knowledge of those network footprints.

"It's not prioritisation so much as reallocation, and that's purely on what makes the most economic sense in each area," Steiger explained.

This led to Shadow Communications Minister Michelle Rowland accusing the Coalition government and NBN of "abandoning" the HFC network in favour of a slower-speed FttN network that costs the same to roll out.

The wide-scale rollout of NBN HFC was approved by the Australian Competition and Consumer Commission (ACCC) in June 2015, with a revised AU$11 billion deal allowing NBN to take ownership of Telstra's HFC and copper assets and Optus' HFC network.

NBN paid Optus AU$800 million to use and decommission its HFC network, with the original deal signed in 2011 under the Labor government.

Optus welcomed NBN's decision to replace its HFC network with FttDP network technology, saying it would provide more flexibility and less customer disruption.

"FttDP provides design flexibility for rollouts in HFC network areas, and should minimise customer disruption in areas where the current Optus and Telstra HFC networks overlap," said David Epstein, vice president of Corporate and Regulatory Affairs at Optus.

"It is also is a sensible design solution for areas unable to be serviced by fibre-to-the-node technology. FttDP is another addition to NBN's multi-technology mix, and we hope it ensures this important national project can be delivered quickly and efficiently."

While NBN said users will be able to attain peak wholesale speeds of 100Mbps download and 40Mbps upload across HFC, a 4,500-premises HFC trial in Redcliffe in February saw average speeds of 84Mbps down/33Mbps up.

In April, NBN awarded Telstra a AU$1.6 billion contract to provide design and management services of the HFC network until 2020. It also signed a memorandum of understanding with Telstra in December that saw Telstra pick up design, engineering, procuring, and construction within the Telstra HFC network, as well as undertaking to upgrade the HFC network to DOCSIS 3.1.

DOCSIS 3.1 -- currently due to be launched in the second half of 2017 -- would enable HFC users to reach speeds of 1Gbps down/100Mbps up.

In terms of FttDP speeds, the VDSL box currently being used has the capability to deliver speeds of up to 500Mbps, but, once it is updated to a G.Fast box, has the capacity for 1Gbps.

NBN and Nokia are also currently trialling XG-FAST technology with hopes of reaching aggregate speeds of between 5Gbps and 8Gbps across network technologies utilising copper for the last mile.

XG-FAST could be launched by global operators commercially over the next 12 to 18 months, with the FttDP network aiming to launch in 2018.