Following the first announcement of the active measurement network we are planning to set up, you can find a short description below of the equipment we are planning to use for all vantage points.
In the previous article about this new active measurements network, I argued that for meaningful active measurements we'll need a very large number of vantage points, some 50,000 or even more.
In order to deploy such a large number of measurement nodes, they'll need to be extremely easy to deploy and stay running around the clock. The obvious solution that comes to mind is to distribute a piece of software like a browser plug-in following the ideas of Seti@Home and others. The nice thing about this is that distribution costs are very low and the number of potential measurement hosts is very large.
However it also has a number of significant drawbacks: host machines do not run continuously over long periods, the measurements are influenced by sharing systems and network resources with other applications on the host computer, such software is difficult to install in a corporate or computer centre environment, tampering with the results is easy ...
Considering these drawbacks we've decided to go for a very small hardware device powered via USB (see Figure 1). The USB connector is only used to supply power, no data is exchanged here.
Figure 1: Artist's impression of an Active Measurements Probe
This device provides very controlled experimental conditions; we know exactly what software runs and what resources are in use. No other applications influence the measurements. Such a device is also "24/7 friendly" as it consumes very little electricity, can be powered from almost any USB connection and there is no need to switch it off once installed. One typical scenario is to connect it to a home router and power it using one of the router's USB connections. This way, measurements can be performed at any time while the router is on, typically 24/7:
Figure 2: Active Measurement Probe prototype in action
This photograph shows an early prototype of the device performing ping measurements from my home to a number of DNS servers over both IPv4 and IPv6. Note the small size of the device and the fact that it obtains power directly from the router via the white USB cable.
In addition to being easily deployable the device is also much more tamper resistant than a pure software solution; it is quite difficult to interfere with its operation or to change the measurement results directly. Yet one can easily stop the measurements at any time simply by disconnecting the USB cable. Also the device is not really an attractive target for botnet herders; the OS and applications are exotic, there are no open ports facing the Internet and the device does not have a lot of processing power.
We are currently testing prototypes. They look very promising and we are confident that we can deploy 300+ of such a device within the next few months. The challenges are how to schedule measurements and collect results in a network of thousands of devices. Also we have to motivate people like you to host the probes and find sponsors for both the hardware and operating costs of such a network. We have quite some good ideas on how to do that. Stay tuned!