Recently ICSI researcher and Netalyzr co-developer Nick Weaver participated in a disussion with Vint Cerf, Van Jacobson, and Jim Gettys of bufferbloat, the tendency of network equipment to employ excessively large buffers that impose unnecessary latencies on network traffic. Netalyzr measures these buffer sizes, and the findings we reported in our IMC'10 paper have attracted significant interest in the community.

The roundtable discussion formed the basis of a feature in the February edition of the Communications of the ACM. The resulting article, BufferBloat: What's Wrong With the Internet?, is now online.

We have just released a substantial Netalyzr update. First and foremost, we've made Netalyzr a whole lot faster. After analyzing the test durations experienced by our users, we increased parallelization in test executions and optimized a number of timeouts, all with the goal of reducing execution time. Netalyzr now runs approximately twice as fast and a session typically completes in under two minutes.

We have also improved the level of control you have over the amount of information displayed on the test results page. You can now expand and collapse details of individual tests, instead of entire test categories. In the initial results display, this ability lets us show details only for tests that exhibited irregularities or problems, while keeping all other results collapsed. See the help page for more information.

Several users reported that Netalyzr's bandwidth test at times crashes their DSL modems, causing a temporary loss of network connectivity. This outage could cause Netalyzr sessions to stall at the result upload stage. We now attempt result uploads several times while waiting for connectivity to resume. You may have noticed that Netalyzr tries to use the UPnP protocol to identify the model and manufacturer of your gateway device. In the future, this information, combined with tracking outages induced by bandwidth tests, will allow us to identify particularly fragile devices.

For researchers we now provide better ways to label Netalyzr sessions and obtain the resulting set of result data. Netalyzr has long provided a command-line interface, but no convenient way to obtain test results for subsequent processing. In addition to the regular HTML summary we now also provide the session results in JSON format. To obtain a session's results in JSON, use this URL schema:

http://netalyzr.icsi.berkeley.edu/json/id=[session ID]

Here's our example session in JSON. Note that we're still in the process of improving the details reported for individual tests. We'd love to hear your feedback on this data format—discuss it with us on our mailing list.

If you're a researcher providing customized ways for people to run Netalyzr, you can now arrange to have all resulting sessions automatically tagged with a string identifying your experiment and retrieve the list of resulting sessions in near-real-time, likewise in JSON format. If you're interested in this feature, please contact us.

As we're approaching the 500,000 session mark, we'd once again like to thank our users for their ongoing support and use of the Netalyzr service. We couldn't do this without you!