Double-ups in phone network beat the floods

By PETER GRIFFIN

Telecoms providers are counting the virtues of network "redundancy" after last month's floods pushed them to their limits.

Telecom boss Theresa Gattung told the Herald last week that outages caused by the flooding were the "single biggest network event in the last 10 years" for Telecom.

About 6000 Telecom customers in the lower North Island had their phone services disrupted at the peak of the flooding.

Main fibre and copper cables were knocked out at 40 river crossings when bridges were washed away or swamped by floodwaters.

But the complexity of Telecom's network meant national call and data traffic was not disrupted.

Long-distance traffic was automatically switched to unaffected links. Local connections were harder to repair, as new lengths of cable had to be strung across waterways.

"In places like Marton, we had to do special work because of the number of hits on the network," said Telecom's manager of network operations, Rob Powell.

"There's a huge amount of diversity built into the network, and we do crisis management role-play exercises once a year."

But TelstraClear, New Zealand's second-largest fixed-line network operator, came close to losing service on its national network.

It operates a ring network of fibre through the North Island, so if one section of the ring is knocked out, traffic can still be routed to its destination the other way.

A landslide severed the fibre on the eastern ring, and subsidence in Manawatu stranded a train on tracks alongside which TelstraClear's back-up cable runs.

"The risk we faced for a while was that in realigning the track they may have had to move the cable. Fortunately that didn't happen," said TelstraClear spokesman Matthew Bolland.

TelstraClear warned its business customers of a possible five to six hour cut in service while the train was moved from the damaged tracks.

It would have lost frame relay and ATM (asyncronous transfer mode) services, creating a major disruption for its corporate customers .

Some residential services would also have been lost.

The eastern fibre link was restored before Tranz Rail began salvaging the train, and the operation did not disrupt TelstraClear's cable.

A Transpower pylon fell on a TelstraClear cable severing it at the top of the South Island. In the North Island, a 200-metre section of cable was ripped from the ground but continued to function.

Telecom was able to divert most incoming calls to disconnected landlines to mobile phones at no charge.

Powering telecoms equipment was a headache as electricity lines succumbed to flood waters.

"There were huge issues with power supply through the whole thing," said Powell.

Vodafone spokeswoman Sarah Williams said the operator was on the verge of flying in its own generators to combat loss of power at its cell sites in the lower part of the North Island but power was reconnected.

The elevated position of Broadcast Communications' transmission sites meant they escaped damage from flood waters.

"We did look at moving traffic around on our network so we could step in if needed," said spokesman Matt Bostwick.

He said wireless was ideal as a back-up because it was less susceptible to major outages.

But BCL did fall victim to high-speed wind gusts after the flooding. A generator powering its TV and radio transmitter in Taranaki was knocked out for half an hour.

Backhaul for wireless data services was powered separately and was unaffected.

The operators are yet to put figures on the cost of repairs, but all agree it will be significant.

"A lot of damage was done to assets," said Bolland.

Said Powell: "All those costs are still coming in - there is going to be huge cost."