The incorrect broadcast of these routes effectively hijacked the IP address ranges of a number of other providers in Australia, including Launceston-based Launtel.

The chief executive of Launtel, Damian Ivereigh, told iTWire, that he had seen the Launtel network go down primarily to the ACT at about 6.50am AEDT.

"By 8:20am, others started reporting on AusNOG (the Australian Network Operator Group mailing list), that they were seeing traffic to their networks being 'hijacked' by Telstra, asking if anyone from Telstra was able to assist," he said.

"It quickly escalated on the mailing list where many providers were reporting similar issues. An unofficial Telstra employee briefly appeared on list at around 9:00 to report the issue had been resolved."

Ivereigh said he had no idea what had happened inside Telstra. "But from the outside, they clearly started advertising incorrect 'BGP prefixes' to the Internet and effectively took down a number of other ISPs and content providers," he said.

Contacted for comment, a Telstra spokesman said the error was caused by a third party who was adding pre-approved IP ranges within the Telstra Internet Direct network which resulted in the mistaken redirection of some traffic.

"As soon as we identified the issue, it was resolved," the spokesman added.

For those who are unaware of BGP, Ivereigh said when it came to inter-carrier routing, carriers (and content providers like Google, Facebook etc) often needed to send traffic to each other.

"They rely on a protocol called BGP — Border Gateway Protocol — which essentially allows each carrier to broadcast to each other what IP address ranges (called 'prefixes') should be sent to them. We, for example, announce to the world that any traffic for the IP address range 103.216.190.0 to 103.216.191.255 should be sent to us."

Ivereigh said the security of the process was "not great" and one carrier could announce incorrect prefixes and effectively take over the address ranges of another provider (and take them down).

"This is limited only by the level of trust that each carrier puts on another carrier when they receive an advertisement. However, generally speaking, most trust Telstra to get this correct and so accept their advertisements without question," he said.

"So Telstra are clearly able at any time to switch off a number of other providers should they so choose. Worse, unless people are in the know, they would assume this is a fault of their provider. There are security layers being added to BGP, but the take-up is slow. Perhaps this needs to change as more of our business is conducted on the Internet."

This is the second BGP hijack reported this week. On Tuesday, Australian time, Google was affected by network issues which turned out to be due to an ISP in Africa broadcasting wrong routes.

MainOne, the ISP which was responsible for the error, said later that it was due to a misconfiguration on its BGP filters and the error lasted for 74 minutes.