Last week, the Skype VoIP service went down for two days, affecting customers worldwide. On Monday, Villu Arak, writing on the Skype blog Heartbeat, attributed the outage to "a previously unseen software bug within the network resource allocation algorithm which prevented the self-healing function from working quickly."
But the root cause? "The disruption," he said, "was triggered by a massive restart of our users' computers across the globe within a very short time frame as they rebooted after receiving a routine set of patches through Windows Update." Tuesday Microsoft pushed out nine patches, six of which were deemed critical.
Skype works by distributing the process of making calls over the Internet among its many users. This peer-to-peer architecture allows the international voice over Internet Protocol (VoIP) service to be offered for free between users, and to landlines for low prices. However, shortly after the latest round of updates from Microsoft last week, the network experienced a high number of system restarts, draining Skype's resources. After the system restart, users must then log back into the service and that, combined with fewer global resources, produced the outage, according to Arak. He said the software bug has been identified and improvements are being pushing out to the network.
Arak also ruled out any nefarious action by others. The outage coincided with the online release of a denial of service for Skype exploit code from a group at Securitylab.ru, but Arak denied that. "We can confirm categorically that no malicious activities were attributed or that our users' security was not, at any point, at risk."