How Important is Skype to You?

Skype is my main source of communication.  I use Skype for work.  I use Skype to talk to my friends that live oversees or in other states.  I use Skype to talk to my family daily.  I use Skype for both business and personal purposes, probably as do most of you reading this blog.  Millions of Skype users worldwide experienced connection issues with Skype starting at 9am PST on Wednesday, December 22, 2010.  As the day went on, connection issues turned into a complete outage.  This marked the second time in 2010 that Skype was hit with a major outage.  Most users experienced approximately a 24 hour outage.  Different features of the website, such as video conference chat and phone calling, became unusable throughout the day, trailing behind one another.  In the next 24 hours Skype slowly restored service.  The last feature to return was Skype’s conference video calling, a feature many of us use daily to stay connected with those we work with, are related to or are close friends with across the nation and in other countries.

"For a communications system this large to go down, it's almost unheard of," said Charles S. Golvin, a Forrester Research analyst. "Usually when phone lines are disrupted, the blackout is confined to a specific geographical area. This is worldwide."

So what happened?  Skype first noticed a problem when the number of people signed into the website dropped off significantly in a short period of time.  Skype says the outage was due to many of its supernodes going offline at the same time.  Supernodes act as a phone directory for Skype.  If a user is attempting to locate someone online and the Skype application is not able to find that someone, the user’s computer or phone will first try to find a supernode to figure out how to reach that them. 

Basically, Skype servers became overloaded with client requests and a significant number of supernodes had already failed.  A supernode is important to the peer-to-peer network because it takes on additional responsibilities compared to regular nodes, acting like a directory, supporting other Skype clients, helping to establish connections between them and creating local clusters typically of several hundred peer nodes per each supernode. Once a supernode has failed, even when restarted, it takes some time to become available as a resource to the peer-to-peer network again. As a result, the peer-to-peer network was left with 25–30% fewer supernodes than normal. This caused a disproportionate load on the remaining available supernodes.

What is a supernode? In peer-to-peer networking, a supernode is any node that also serves as one of that network's proxy servers, handling data flow and connections for other users. This semi-distributed architecture allows data to be decentralized without requiring excessive overhead at every node.  These supernodes run the Skype software. 

How does Skype use supernodes? Skype, by default, is configured as a supernode, an issue that has caused controversy. Despite criticism, Skype has contended that supernodes on their network act only to maintain information about who is online at a given time, and are not used to route calls between users.  Supernodes connect individual Skype clients to each other that create a peer-to-peer network, the cloud that connects all Skype users to each other.  The only difference between “regular” supernodes and those that Skype uses are that the ones Skype use are on a public network.  If a user is   running Skype on a computer and is not behind a firewall, there is a large chance the user’s computer can become a supernode.  See the image below for an illustration. 

How did Skype reciprocate?  During the outage, several Skype Executives took to the blog, posting sincere apologies and continually updating users about the status of the outage.  After service was restored, Skype rendered a formal apology for the outing via their blog, as well as, issued 30 minute talk time vouchers to most users.  Skype’s CEO issued a formal and heartfelt apology on the company's official blog, formally discussed the issues that caused the outages and offered compensation to the millions of affected users. A word from Skype CEO, Tony Bates:

“I would like to take a moment to thank each of you for your patience, understanding, and support during Skype’s outage. We know how important your Skype conversations are to you and we take any disruption to our service very seriously.”

When the Skype outage occurred my day was greatly impacted.  Was yours?  We would love to know; comment below!