Updated: ADSL emulation port scrapped from NBN plans

NBN subscribers won't be able to utilise existing internal copper wiring for their home network

NBN Co has confirmed the Network Termination Unit (NTU) being installed on residents' homes as part of the National Broadband Network (NBN) rollout will not have an ADSL emulation port among its set of interfaces.

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The port was initially slated for all first-generation Alcatel-Lucent NTUs installed on homes during the mainland rollout, but was conspicuously missing from the fibre access technical specifications released by the NBN wholesaler in August. A spokesperson for NBN Co confirmed the specification had been dropped.

“NBN Co is no longer providing an ADSL emulation port on the NTU,” they said. “The key reason being feedback from RSPs (Retail Service Providers) that this is not how they intend to do their migration.”

It is believed some technical issues in successful emulating an ADSL connection over copper wiring from the NTU may have also have been to blame for the port’s exclusion.

Instead, the technical specifications state that residential NTUs will include four 10/100/1000BaseTX Ethernet ports capable of speeds of up to 1 gigabit per second Gbps, along with either one or two SIP-based telephony ports that will allow any home to use their existing phone for telephony provided they have a VoIP service. Business-based NTUs will include the four Ethernet ports but not the SIP-based interfaces.

Alcatel-Lucent declined to comment on the matter.

An ADSL emulation port would transmit data over the existing internal copper wiring in subscriber’s homes, allowing them to forgo rewiring their house with Ethernet.

A report from The Australian in August claimed the extra rewiring could cost homes up to $3000 extra to take advantage of the faster speeds between one or more computers, a claim the Opposition has been quick to pick up on. However, Prime Minister Julia Gillard discredited the claims as raising fears in residents.

While subscribers could also use a Wi-Fi router connected directly to the NTU, even the fastest 802.11n wireless standards often operate at real world speeds lower then the 25, 50 or 100 megabit per second (Mbps) connections the NBN currently offers.

Those who received an NBN connection to their homes as part of the Stage 1 Tasmanian rollout have already faced a similar problem, as the NEC-branded NTUs installed there also lack the ADSL emulation port. However, Robert Pettman - a senior IT support officer at Tasmania Polytechnic and one of the first NBN subscribers - has said he and those he knows have managed without the emulation port.

“I have a bit of CAT6 running around my house, that was there already from my old service,” he said. “I think everybody has had theirs installed where needed. I personally haven’t heard of anybody having to outlay any additional costs to get any cables and that kind of thing installed.”

However, he did say that using a wireless device showed a dramatic decrease in speed over devices in his own internal Ethernet network.

The National Broadband Network End User Premises Handbook released by industry group Communications Alliance in June called for NTUs to support numerous interfaces including Ethernet connectivity, support for traditional telephony devices and potentially an RF interface for transmitting video by IP to houses in greenfield estates.

The document also recommended the possibility of an ADSL emulation port delivering speeds of more than 100Mbps to distances under 300m, or possibly a HomePNA port, which similarly utilises telephone wiring to deliver speeds of up to 320Mbps over short distances. However, the group’s chief executive, John Stanton, said these points were not deal breakers for migration to the network.

“It’s not something that the industry has been pressing for change on,” he said. “It was not something that the industry working groups pressed for because of the transitional nature and the potential technical challenges.”

Instead, Stanton said RSPs would likely offer alternative methods such as Wi-Fi routers as well as differing commercial strategies to suit a range of users.

Internode managing director, Simon Hackett, agreed that the emulation port was merely transitional, but said he did not know enough details about NBN Co's change as yet.

"I can't see any merit in an ADSL emulation port," he said. "Why bother, when the unit has multiple 100Mbps (or faster) Ethernet ports, and the better ADSL2+ routers can be reconfigured in software to use one of their Ethernet switch ports as a 'WAN' port. i.e. you'll be able in many cases to just re-patch your current (or then-current) router direct into the NBN box inside your house using an ethernet cable and have all your old stuff keep working - just... faster."

Despite the lack of an ADSL port, iiNet has continued to push its BoB device - an ADSL2+ wireless modem router - to its NBN customers.