WAN Optimization and the AutoCAD Problem – Why Networks Fail (to Perform)

Part 5 in a series adapted from Joel Trammell’s Keynote Speech at NetQoS Symposium 2008
One of the big downsides to WAN Optimization is that you’re breaking up the TCP session that used to be from one end of the network to the other into three independent TCP sessions.
To measure the response time after WAN optimization is deployed, NetQoS worked with Cisco to develop code that exists on every Cisco WAN optimization device that ships. That solved the problem – at least for Cisco WAAS users.
But if I can generalize, you talk to a WAN optimization vendor and they will tell you, “Well, who cares about breaking up the TCP session because we’re going to make your network so good you’re not going to have to deal with performance problems.”
That’s not reality. They will solve a certain set of performance problems, to be sure, but in some cases they may exacerbate problems.
For example, earlier this year, I recall that a Riverbed box had serious issues around AutoCAD. When AutoCAD changed the file format version, the WAN optimization implementation was actually slowing down AutoCAD. That’s an important area that people don’t necessarily think about when they deploy WAN optimization: Did it actually do any good and how can you quantify how much good it did?
You have to do some pretty sophisticated analysis to understand what applications are going to benefit from WAN optimization, or any other technology addition for that matter, and which aren’t. It’s not always obvious how much data reduction occurred. That’s one of the big selling points, right? You’re not going to have to transfer all this volume across the network; well can you quantify how much data reduction occurred on the network?
Finally you want to be careful what applications may break when they’re optimized. So, with WAN optimization the network performance metrics you’ll want to see are response time and traffic flows. That ability to understand and “re-put together” the three response time segments that were broken by putting in WAN optimization in the first place.
[Ed. Note: 17 November - In our comments section, Bob Gilbert from Riverbed points out that the AutoCAD problem has been addressed with a patch from Autodesk, and that the problem with AutoCAD's .dwg files were not Riverbed exclusive.]