The Computer Corner
By Charles Miller

If you want to stir up a hornet’s nest, just give away something for free, then stop doing it. To really stir things up, try not telling anyone why they cannot have it any more.

For two days, August 17 and 18, this was the situation facing the 220 million users of Skype, many of whom are here in San Miguel de Allende. Until then, these users contentedly used this Voice over Internet Protocol (VoIP) service to make free or low-cost phone calls via their computers. Suddenly, for two days nobody could make any calls.

Skype uses peer-to-peer technology to connect calls, rather than routing them through a central server. It relies on a large number of users’ computers to route calls through to other users. This innovative technology decentralizes the system and harnesses the processing power of millions of computers to make calls. There are varying opinions as to the resiliency and capacity for expansion of this “supernode technology.”

At peak usage hours, Skype can have five million users logged on and talking. Skype had not previously had any serious long-term outages, and many industry professionals marveled at its reliability. This outage is bound to undermine the confidence many people had in Skype.

As this column goes to press, the source of the outage was not fully known. Skype’s chief security officer, Kurt Sauer was quoted in the New York Times as saying that what had happened was caused by “a unique set of events, the genesis of which is not entirely understood.” Later Skype stated that “This problem occurred because of a deficiency in an algorithm within Skype networking software.”

That explanation raised more questions because according to Skype engineers the flaw has existed in every version of the Skype software since 2003. Many were curious why the bug had been dormant for four years only to affect the network now.

One theory put forward by some VoIP experts is that Skype has been a victim of its own success. There has never before been any telephone network with two hundred million users, and it is not known whether the software will be able to accommodate the increased number of users.

The conspiracy theorists did not lose much time jumping on this event. Various Internet forums were buzzing with allegations that Skype was working closely with the CIA and NSA to add wiretapping capabilities to enable eavesdropping on terrorist conversations. Supposedly, the phone-tapping scheme crashed the network.

Some others noted that the start of the Skype outage coincided with Microsoft’s “Black Tuesday,” the second Tuesday of every month when Microsoft releases updates and patches for their Windows operating system.

A more plausible explanation is the fact that Skype performed some routine network maintenance on August 15, and soon after that the problems began. The likelihood is that some software change during this update precipitated a cascade failure that eventually affected all the servers on their network.

If this proves to be the case, then Skype needs to rehearse some worst-case scenarios that could occur during future maintenance, and plan their response for fixing any problems that might occur.

220 million is a lot of people to be left with no dial tone.

Charles Miller is a freelance computer consultant, a frequent visitor to San Miguel since 1981 and now practically a full-time resident. He may be contacted at 044-415-101-8528 or email FAQ@SMAguru.com