The company I work for has been implementing thin client technologies based on Citrix and Microsoft Terminal Services for a long time.  Today, VMWare’s Virtual Desktop Infrastructure (VDI) is starting to be the hot item.  This post addresses the network concerns presented by thin client technologies.  My first experience with this issue was presented by a small branch employee playing ‘Wheel of Fortune’ online.  The network died every time it was her turn to spin the wheel.

The term “thin client” is misleading in terms of networking.  Thin only refers to the hardware requirements for the client.  It does not mean the technology is thin on the network.  Apparently thin client technologies are great for centralized control, network management, cost savings and other things that I really have no authority to speak on. However, in regards to the network, it only takes one client to destroy a wan link or internet connection.

Update: This post is not intended to guide anyone away from thin client technologies … whether it be server based or virtualized desktops. The intent is to inform individuals of how much traffic can be generated by thin client technologies if mis-used, are poorly designed or simply not understood. The video was not produced by a device with acceleration technologies. It is just simple Microsoft Remote Desktop Protocol.

I will demonstrate how much bandwidth can be consumed by a thin client session.

Do the following:

  1. Open the ‘Task Manager’ on your PC
  2. Click on the ‘Networking Tab’
  3. Click on ‘View > Select Columns’
  4. Check ‘Bytes Sent/Interval’ and ‘Bytes Received/Interval’
  5. Click ‘Ok’
  6. Establish an RDP session with a Microsoft Server/PC on your local area network.
  7. Open YouTube
  8. Play a video that is very interactive like a football game.
  9. Make note of the Bytes Sent and Bytes Received
  10. Multiply the Bytes Sent and Received by 8 to get bits per second.
  11. Now you see how easy it is to kill a network with a thin client.

Why does this happen?

Everything happens at the server. The server just sends the screen to the client.  Sounds thin enough … but when the screen is trying to keep up with screen changes produced by video, stock tickers, games …  bandwidth is consumed. Even a clock updating seconds can generate more traffic than you think.

The next time your internet is slow, check traffic to, or If the internal wan is slow and network traffic is heavily tcp port 3389 (rdp) or tcp port 1494 (Citrix) … you might want to check the user’s activities.

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