Networking Equipment and Virtual Machines Do Not Mix


By Joe DEsopo

Editors Note:
We often get asked why we don’t offer our NetEqualizer as a virtual machine. Although the excerpt below is geared toward the NetEqualizer, you could just as easily substitute the word  “router” or “firewall” in place of NetEqualizer and the information would apply to just about any networking product on the market. For example, even a simple Linksys router has a version of Linux under the hood and to my knowlege they don’t offer that product as VM. In the following excerpt lifted from a real response to one of our larger customers (a hotel operator), we detail the reasons.

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Dear Customer

We’ve very consciously decided not to release a virtualized copy of the software. The driver for our decision is throughput performance and accuracy.

As you can imagine, The NetEqualizer is optimized to do very fast packet/flow accounting and rule enforcement while minimizing unwanted negative effects (latencies, etc…) in networks. As you know, the NetEqualizer needs to operate in the sub-second time domain over what could be up to tens of thousands of flows per second.

As part of our value proposition, we’ve been successful, where others have not, at achieving tremendous throughput levels on low cost commodity platforms (Intel based Supermicro motherboards), which helps us provide a tremendous pricing advantage (typically we are 1/3 – 1/5 the price of alternative solutions). Furthermore, from an engineering point of view, we have learned from experience that slight variations in Linux, System Clocks, NIC Drivers, etc… can lead to many unwanted effects and we often have to re-optimize our system when these things are upgraded. In some special areas, in order to enable super-fast speeds, we’ve had to write our own Kernel-level code to bypass unacceptable speed penalties that we would otherwise have to live with on generic Linux systems. To some degree, this is our “secret sauce.” Nevertheless, I hope you can see that the capabilities of the NetEqualizer can only be realized by a carefully engineered synergy between our Software, Linux and the Hardware.

With that as a background, we have taken the position that a virtualized version of the NetEqualizer would not be in anyone’s best interest.   The fact is, we need to know and understand the specific timing tolerances in any given moment and system environment.  This is especially true if a bug is encountered in the field and we need to reproduce it in our labs in order to isolate and fix the problem (note: many bugs we find our not of our own making – they are often changes in Linux that used to work fine, but for some reason have changed in a newer release and we are unaware and that requires us to discover and re-optimize around).

I hope I’ve done a good job of explaining the technical complexities surrounding a “virtualized” NetEqualizer.  I know it sounds like a great idea, but really we think it cannot be done to an acceptable level of performance and support.

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