What caused the major network failure?

Tett said Border Gateway Protocol is how network owners and operators’ routers share routing information.

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“Take for example the fence you share with your neighbour. I have a note for you to pass to the neighbour next door that says ‘I love them’. Instead of putting the one address to next door, I accidentally put ‘everyone’, then you go off and try to deliver that note that I love them to EVERYONE, which results in you handing off that note to everyone on your BGP routes.”

An Optus source, who did not wish to be named because they were not authorised to speak publicly, said a BGP prefix flood from a peer was likely causing the issues on the telco’s core network.

The dodgy instruction could have been sent from an internet exchange (a physical location similar to a data centre, where multiple internet providers and network operators interconnect their networks) or directly from an internet provider itself or a content provider.

Is a cyberattack to blame?

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It’s too early to rule out a malicious attack, though Optus chief executive Kelly Bayer Rosmarin says there are no indications of the outage being due to a hack or cyberattack, despite Optus suffering one of Australia’s most significant data breaches late last year.

How long will it take to fix?

Before services began to return to normal just before 1pm on Wednesday, Optus had not provided a firm timeline for when the outage would be resolved. Routing issues often took hours to fix, according to Tett.

“The problem with routers, particularly if it is configuration [issue and] not an attack, is that one major change has to propagate throughout the network and then a fix also then needs to propagate,” he said.

“[The fix] can take hours, particularly if the network is slammed through mis-routing.”

Why is the Optus network outage connected to public transport and hospitals?

Optus’ network infrastructure runs far deeper than just 4G and 5G mobile phone towers. Fibre networks like that from Optus are the backbone for all telecommunications services, including 5G and 4G, as well as eftpos, public transport infrastructure and hospitals, which were all affected on Wednesday.

What’s the government saying?

Earlier on Wednesday, Communications Minister Michelle Rowland called on Optus to “step up” its public communications to customers as people are “hungry for information”.

“I think Optus needs to make sure they step up and communicate with people because, as I understand it, this started in the early hours of this morning,” she said. “We’re now at 11 o’clock and for a lot of people who are trying to get on with their day and their business this is absolutely vital that they get back to normality.”

Will customers be eligible for compensation?

If you have been disadvantaged or lost money due to a phone or internet outage, you might be able to claim compensation, according to ACCAN, the peak advocacy group for Australian communications consumers.

“Compensation should make up for your loss,” ACCAN says. “For example, if your internet is out for one week you could ask for your money back for that week. You may be able to claim for costs incurred, like getting your internet fixed or using extra mobile data.”

“Work out how much money you or your business has lost because of the outage, including any costs for an interim service. Keep documents such as bills and receipts as evidence, record when the outages happened, and how long they lasted.”

“Contact your service provider to explain the problem, and to ask for compensation, and give your service provider the evidence you have collected.”

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