Skype Outage caused by Windows Update

August 20, 2007
I'm never one to say I told you so, but it appears I was right about Windows Update (Patch Tuesday) causing the massive Skype outage. Many users were skeptical of this theory, as seen in the comments of my blog post. This from Skype Heartbeat:
On Thursday, 16th August 2007, the Skype peer-to-peer network became unstable and suffered a critical disruption. The disruption was triggered by a massive restart of our users’ computers across the globe within a very short timeframe as they re-booted after receiving a routine set of patches through Windows Update.

The high number of restarts affected Skype’s network resources. This caused a flood of log-in requests, which, combined with the lack of peer-to-peer network resources, prompted a chain reaction that had a critical impact.

Normally Skype’s peer-to-peer network has an inbuilt ability to self-heal, however, this event revealed a previously unseen software bug within the network resource allocation algorithm which prevented the self-healing function from working quickly. Regrettably, as a result of this disruption, Skype was unavailable to the majority of its users for approximately two days.

When the outage first happened, I wrote, "Since Skype is a P2P network that relies on other peers for the network to function properly, it's possible a Microsoft update is causing a conflict." I also stated, "the major Microsoft updates (Patch Tuesday) that were released yesterday could have something to do with the Skype outage" In the comments section I expound on this theory when I wrote,
"The theory about Microsoft updates causing the Skype problem didn't mean other operating systems weren't affected, such as the Mac.

The theory was that a Microsoft update somehow changed the TCP stack or changed how the Microsoft operating system interacted with Skype. Let's assume the vast majority of Windows users set their patch to auto-install. Then let's assume Skype is 80-90% Windows users. That means that a lot of Windows users installed the patch last night and lots of Windows supernodes could be knocked offline.

The side effect would be that without enough Windows supernodes, Mac users would be booted as well. Though you'd think the network would be flexible enough to handle millions of Windows users knocked offline."

So I guess we have Microsoft to thank for the Skype outage. Or we can blame Skype for not anticipating a worldwide massive reboot of Windows machines. Gee, I could have told them that would happen.

Post a comment
Tags: , , , ,

Search Technorati: , , , ,
Related Tags: , , , , ,

Listed below are links to sites that reference Skype Outage caused by Windows Update:

Trackback Pings

TrackBack URL:
http://blog.tmcnet.com/mt3/t.fcgi/33312

Comments to Skype Outage caused by Windows Update


  1. VoipUser :

    I can't believe Skype had such a failure. I used to use them a bit, but now I use GRN for my voip needs www.grnvoip.com. Haven't had any major problems. Do you know which other carriers have had recent failures?


  1. Dan York :

    Tom,
    The question I raised over on my blog, though, was simply this: why were the restarts associated with the August 2007 Microsoft updates any different from the restarts associated with the MS updates of any other months in the past X number of years?
    http://www.disruptivetelephony.com/2007/08/its-official---.html

    Dan


  1. Judson :

    Tom,
    My hats off to youwink


(If you haven't left a comment here before, you may need to be approved by the site owner before your comment will appear. Until then, it won't appear on the entry. Thanks for waiting.)