Massive Network Outage Disables Skype Users

Skype suffered a serious server outage yesterday that left hordes of its 560 million or so worldwide users without PC calling capabilities for over three hours.

Skype, the voice over IP (VoIP) service people use to make free and low-cost long-distance calls from their PCs and phones, began going down for users around 16:00 GMT, according to ReadWriteWeb.

Supernodes Went Supernova

Twitter was lit up with complaints from users unable to access the service and the company itself addressed the problem around 19:00 GMT in its blog and on its official Twitter account.

Skype’s blogger-in-chief Peter Parkes said that after it noticed the number of users online fell it found that its “supernodes” had failed. Supernodes are clusters of computer servers linked by peer-to-peer networking software.

“Under normal circumstances, there are a large number of supernodes available,” Parkes said. “Unfortunately, today, many of them were taken offline by a problem affecting some versions of Skype.”

Skype employs millions of connections between supernodes, which are virtual phone directories, and phones to run. When a user clicks to place a call on Skype and the app cannot locate a user’s computer or phone will attempt to ping a supernode to connect the call.

With failing supernodes, millions of people were unable to make calls. Skype built new “mega-supernodes”, which are presumably more powerful computers .

As of 20:30 GMT, Parkes tweeted on Twitter: “Skype is now gradually returning to normal – we expect it may take several hours for everyone to be able to sign in again, however.”

Unfortunate Timing

The outage turned tech pundits who rely on Skype to communicate with colleagues cranky. GigaOm’s Om Malik wrote in a blog post: “The outage comes at a time when Skype is starting to ask larger corporations for their business. If I am a big business, I would be extremely cautious about adopting Skype for business, especially in the light of this current outage.”

This issue comes at an inopportune time as Skype is reportedly trying to raise $1 billion for an initial public offering (IPO) for 2011.

This will hardly be the biggest Skype failure. That dubious honour came in August 2007 when Skype went dark for its then 220 million users for two whole days. That outage was triggered by a massive restart of users’ PCs across the globe as they re-booted to complete a Windows update.

Skype engineers later discovered a software bug within the network resource allocation algorithm that prevented the service from righting itself.