After talking about ping pong testing, how about the bouncing ball chaos?


In VSTS 2010 in the world of ping-pong testing we introduced the ping-pong effect. In this post we will be introducing a slightly more energetic bouncing ball chaos … if you are using hyper-v or virtual machines in an environment where many machines are communicating with each other or a server, or if you are experiencing a Team Foundation Server (TFS) and Visual Studio Team System (VSTS) that is slooooooooow or showing weird erratic and/or freezing symptoms then stay with us for the next few paragraphs. image


I can already sense Zayd going tsk, tsk, tsk … 🙂
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Context



  • Imagine one Team Foundation Server (TFS) running on either a virtual or a physical server, with the monitoring tools showing close to no utilization of memory and processor.

  • Imagine many, say twenty, virtual workstations running Windows 7 and Visual Studio Team System (VSTS) and accessing team projects, reports, build, source control and other services from the TFS server.

  • Visualize many software engineers tearing their hairs out, with VSTS freezing up, taking forever to check-out code from TFS and generally acting very, very strange.

  • Tasks that that typically take seconds, run for ever … in fact I started a check-out, went to lunch, came back and stared at the screen … ~10% done. Doing the same task on my laptop against a server on the other side of the US/Canadian border takes a few seconds … hmmmmmm…

Where do the chaotic bouncing balls come into effect?


Well, we finally figured out what the problem was and in my mind I had an image of thousands of bouncing balls going berserk in a small room … all virtual machines had the same MAC address and therefore the confused network packets turned into a chaos of packets bouncing around the network, seldom reaching the server and less seldom making their way back to the originating workstation.


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What did we do to calm the chaos and restore performance and stability?



  • When running Hyper-V you can literally click a checkbox to create a unique MAC address for each virtual machine.

  • When running Windows 7 and Virtual PC, you need to do a bit more:


    • Start the virtual machine and logon.

    • Go to Control Panel\Network and Internet\Network Connections, right-click on the relevant network connection and select properties.

    • Select configure and then advanced.
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    • Find the property Network Address and set it to a unique address manually.

    • Confirm the changes, sit back, watch the crazy bouncing balls evaporate and the network packets getting back on their structured and efficient network journeys.
      Blue Man Exercising on a Cross Trainer Clipart Illustration … each network data packet pacing itself.

Well, the check-out that ran forever and stopped at 10%, completed in a fraction of a few seconds … go TFS, go.


I cannot, however, get rid of the feeling that Zayd is still going “tsk, tsk, tsk” and that we had a similar problem back home in South-Africa a long time ago.

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