ADSL international outage explained

Despite reports to the contrary, there was no cable break on SAT3 last week Friday (29 June 2012). This is what Telkom told MyBroadband when asked about the international connectivity outage that affected many ADSL subscribers this weekend.

The issues experienced by South African Internet users were caused by a “planned maintenance event” which is in progress on the Europe-India-Gateway (EIG) cable between Portugal and Gibraltar, Telkom explained. “Traffic from cables landing in Portugal and extended via EIG to London or Europe will be impacted by the EIG maintenance intervention,” said Telkom.

Network status notices issued by Telkom indicate that the EIG cable outage was expected to end on 1 July 2012. Telkom has also warned of several ongoing interruptions that are expected until the completion of the maintenance on 5 July 2012.

This won’t impact its customers, Telkom said, as its network has sufficient redundancy to ensure ongoing connectivity for its users. “Latency will increase for some services and a small degree of congestion may result,” Telkom said.

Rupert Bryant, co-founder and COO of Web Africa confirmed that EIG was the cause of their headaches on Friday and not SAT3.

Rupert Bryant portrait
Rupert Bryant

“The EIG system is used by most SA Internet Service Providers to backhaul SAT3 to London and as such took down a lot of the SA SAT3 capacity,” Bryant said.

Asked whether the outage was indeed planned, Bryant explained that there was maintenance scheduled on segment 2.3 of the EIG system for 29 June 2012. “This segment is not used in the backhaul from Sesimbra, Portugal to London (2.1 and 2.2) and the work was not expected to impact these services,” Bryant added.

The cable operator then issued Emergency Planned Maintenance notices at 02:00 GMT on the morning of the 29th shortly before powering down segments 2.1 and 2.2, taking down the London route.

“This unfortunately didn’t give operators enough time to schedule work windows and send out notifications or make alternate plans for routes,” Bryant said.

Telkom explained that the repair of EIG required extensive power feeding interruptions during the initial part of the maintenance operation. The power feeding was reconfigured early on Sunday morning (1 July 2012) to enable traffic between Portugal and London, Telkom said, while the cable ship continued to perform the repair work on EIG.

“No further significant interruptions are expected until 5 July when the power needs to the normalised,” Telkom said. “This will probably result in an outage of between 4 to 6 hours.”

With all the undersea cables that have come online in South Africa, could Internet Service Providers (ISPs) not have been better prepared for this outage?

“While hind-sight is always 20/20, EIG probably could have been better with their communication to other cable operators,” Bryant said.

Bryant said that over the last few years the networks of local ISPs have become increasingly resilient to single system failures with the landing of cables such as EASSy and Seacom.

“With WACS currently getting deployed that trend is set to increase,” Bryant said. WACS is another undersea cable system off Africa’s West coast for which a launch event was recently held.

“SAT3 and EIG have both been very stable cable systems over the last few years and as the main cable coming into Cape Town the local ISPs’ dependency on this route is still very high,” Bryant said.

In future, Bryant said that WACS would allow most of the networks to run diverse routes out of Cape Town cost effectively, and will allow for better preparedness for this sort of failure.

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ADSL international outage explained