I often run across the need to do “What if” type studies for many of my clients. What if we move the application server from one data center to another? What if we add an additional office to the network? How much bandwidth are we going to need? I have also used many open source tools to assist with this. Dummynet, NIST Net, WANEM etc. While I am a firm believer in open source, sometimes these “free” tools just don’t cut the mustard.
Recently I have been doing a considerable amount of research and testing using the popular WANEM. I have to say, WANEM is nice. It’s easy to use/setup and seems to have most of the features needed for small scale simulations. It was only when I started really cranking up the traffic that it started to fall apart. Now granted, I was using a decommissioned PC (which I suspect most people would) and it wasn’t the beefiest of boxes.
When I started looking at the packets with Wireshark, I was noticing a great deal of dropped packets. That would have been great if I had told the emulator to inject packet loss :). This really got me looking for an alternative solution. As I am sure you are aware, when doing this type of work (predicting response times) it is critical to be correct.
The first time you put your name behind a prediction and it goes south, will be the last time anyone ever seeks your advice. I just don't have faith in a software based emulator after what I experienced when actually analyzing the packets while using WANEM. There are too many variables with a software based emulator. It's great for messing around in my own lab, but would never use it when my reputation is on the line.
As a consultant, I knew what I needed had to be small and it had to be able to fit in my backpack. So the search began…
I was able to get my hands on a Linktropy Mini2 from Apposite Technologies (http://www.apposite-tech.com). I can now say, the search is over. This thing is fantastic! It has a slick web interface for configuration and could easily stand up to any traffic I could throw at it (without unwanted packet loss). This sub $2,000 device should be in any serious network engineer’s tool bag.
Author Profile: Mike Canney is the President of getpackets.com, specializing in providing application and network performance consulting services. Over the past 22 years Mike has helped 100's of companies identify and resolve their application and network performance issues. Mike has also developed coursework and taught thousands of engineers how to identify, remediate, and prevent network and application issues by analyzing traffic flows at the packet level. Mike can be contacted at canney (at) getpackets (dot) com