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Best way to simulate a WAN network

Asked 2008-10-08T10:40:43.990
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Simplified, I have an application where data is intended to flow over the internet between two servers. Ideally, I'd like to test at what point the software ceases to function. At what lowerbound limit (bandwidth, latency, dropped packets) do things stop working to test the reliability of the software.

What I thought I would do was the following:

  1. Setup up 3 machines (VMware instances)
  2. Install the 2 applications on two of the servers.
  3. Setup up the 3rd server to sit between the two machines by doing some sort of magic with Routing and Remote Access on Windows 2003
  4. Install either Traffic Shaper XP or NetLimiter to limit the bandwidth
  5. Run something like TMnetSim Network Simulator to simulate a bad connection.

Does this sound like a good idea or are there easier/better ways of doing this? I'm not that comfortable on Linux and my team mates are even less so.

testing network-programming bandwidth wan
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We had a similar requirement some ten years ago - I'll see if I can recall how we managed it.

If I remember, we wrote a socket proxy program which was controlled by inetd on a UNIX box. This socket would accept connections from a client and open equivalent sessions through to the server. It would then loop, passing messages in both directions.

The way we achieved WAN characteristics was to introduce random delays (with upper and lower limits) in both the connection establishment and the passing of data once the link was up.

It also had the feature to drop the link occasionally as WAN links were less reliable for us than local traffic.

I recall we had to make it threaded to stop the delays from affecting reverse traffic on the link.

answered 2008-10-08T11:52:49.727

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