Cable loss would not cut NZ 'net access

The loss of a portion of the Southern Cross Cable could see New Zealand struggle with internet congestion for up to 10 days, but would not shut internet access down completely, according to the Centre for Critical Infrastructure Protection (CCIP).

Paul McKitrick, manager of the centre, says the Southern Cross Cable (SCC) is built in a figure of eight loop, so a single cut to the cable would see traffic diverted along the other path. That could see congestion issues arise, but would not lead to a total loss of internet access.

McKitrick says there are also legacy cables that were in place before the SCC was built. While these have limited capacity, they would also contribute in an emergency. On top of that, there are some satellite links as well.

“The key impact would be congestion,” he says.

However, McKitrick says it could take up to ten days to repair the cable, assuming five days for a ship to get to the point of the cut and a further five to repair it.

It is likely that ISPs would have to alter their peculiar peering practices during such an event as well. In New Zealand not all ISPs have peering agreements with each other and that means purely local data traffic often has to find an overseas route.

The failure of ISPs to peer would mean local traffic would also be affected by congestion if the cable were cut.

McKitrick says he is advised local peering could be established in a “matter of minutes” should it be required.

McKitrick says the CCIP is mainly focused on deterring cyber attacks and lines of responsibility get blurred when it comes to responsibility for cyber infrastructure.

Telecom is part owner of the company that runs the cable. A Telecom spokesman provided Computerworld with further information on the resilience of the cable.

“Our network comprises two separate cables and is configured in three self-healing rings to provide fully protected capacity,” an SCC document says.

“The equipment used on Southern Cross has been designed to achieve 99.999% availability for protected circuits, and a single failure of a submarine cable section will not cause a loss of service.”

However, the document goes on to say that takes “no account of failures resulting from external aggression, whether these failures are caused by natural aggression, such as earthquake activity, or man-controlled aggression such as anchors and fish trawls”.

That document also states that repairs in deep waters have been known to take up to 50 days.