Upgrades to the $10 billion National Broadband Network (NBN) will be impossible if sub-loop unbundling, part of a call for structural separation, is mandated, according to top Telstra chiefs.

Australia will forever have inferior broadband, according to the telco, if competitors are handed direct access to the NBN nodes and last mile in a similar fashion to the current wholesale arrangement for ADSL.

Telstra chief operations officer Greg Winn said the network will be incapable of upgrading from proposed speeds of 12Mbps to 50Mbps if unbundling is required because it will degrade service quality.

“Sub-loop unbundling is the dumbest, most stupid thing I've ever heard,” Winn, a 35 year networks engineer veteran, told a Sydney conference.

“It will destroy network quality and degrade speeds because fibre technology is not designed for it.

“[The NBN] requires the best of everyone; the skill set and commitment to the timeframe is extraordinary. It requires 24x7 work continuously for five years for the operator to have any chance of meeting the timeframe.”

Winn said sub-loop unbundling should be abolished regardless of what company is awarded the lucrative NBN deal, which will be Australia's largest ever infrastructure investment.

The telco has devoted over three years and some 900 engineers to designing the network, while more than 1000 Alactel engineers have already spent an estimated 1.5 million hours on the project.

“There is no way anyone who started designing a network in April (the launch of the NBN tender) is anywhere near us. I'll go head-to-head with anyone on that,” Winn said.

Node cabinets will be placed at strategic points to create short loops between premises which Telstra network and technology executive director Michael Lawrey said will eliminate the wild latency variations common in ADSL networks. Cabinets will be distributed according to power availability in regional areas.

Lawrey said a “streamlined access” for competitors — meaning the operator alone would have physical access to the network — will preserve line integrity and maintain speeds, while sub-loop unbundling will degrade backhual capacity.

“[Unbundling] is the panoply of regulatory idiocy,” Lawrey said. “It is like tuning the carburettors on a Cortina instead of buying a new Corvette.”

Copper unbundling has caused the drop outs and latency problems in ADSL networks, Lawrey said, because access seekers are allowed to dig up the lines for customer provisioning.

He said huge sectors of the NBN will crash and emergency telephone services will be terminated if providers overfill network lines; a common problem on ADSL networks caused by poor coordination between telcos.