Dasu

The Short Story

Dasu was a measurement experimentation platform for the Internet’s edge. It supported both controlled network experimentation and broadband characterization — building on public interest in the latter to gain the adoption necessary for the former.

Do you ever wonder what your ISP service is really like? Are you getting your money’s worth? How do public DNS services perform compared with your own ISP’s, over the long run?

Some ISPs set complex policies based on time of day, service level or application; others oversubscribe their networks, shape traffic, or discourage heavy users. To the person paying the bill, those policies show up as time-of-day variation in available bandwidth, poor performance for particular applications, or a general sense that the service is worse than advertised. Dasu’s goal was to capture those variations by continuously monitoring the level of service actually delivered, so users could make informed decisions about their provider.

Why Continuous, and Why From the Edge

Most earlier work on ISP performance relied on one-time active measurements from user-triggered benchmarking tools, which capture only snapshots. That approach cannot see service variation or sporadic events, precisely because such things are transient. Many tools also looked at a single dimension — upload and download caps, DNS performance, HTTP caching.

Done properly, ISP characterization needs to be:

• at scale, to cover the diversity of providers and service tiers
• continuous, to catch traffic shaping, oversubscription and unscheduled outages
• from end users, so what is characterized is the service people actually receive

Existing approaches traded these against each other. Our argument was that network-intensive applications already running on end systems — BitTorrent being the obvious one — avoid the trade-off entirely.

By passively monitoring user-generated traffic, Dasu captured the end user’s view at scale. By combining that with on-demand active measurements, it reached the effectiveness of hardware-based approaches such as SamKnows and the FCC’s programme, without their cost, while keeping the flexibility and low adoption barrier of software.

Distribution

Dasu shipped first as a plugin for the Vuze/Azureus BitTorrent client, then as a standalone client for users who did not run BitTorrent — a small application that sat in the status bar monitoring ISP performance, with installers for Windows and macOS 10.5+. Versions ran from 1.0 in May 2010 through 5.0 in 2013, with automatic updates.

It was released under the GPL, with source included in the distributed jar. Neither the plugin nor the standalone client is available today.

Why the Name

Dasu is the Japanese word for putting something out there, or showing something — used especially for showing secrets.

Papers

• Crowdsourcing ISP Characterization to The Network Edge — W-MUST 2011
• Dasu: ISP Characterization from the Edge, A BitTorrent Implementation — SIGCOMM 2011 (demo)
• Up, Down and Around the Stack: ISP Characterization from Network Intensive Applications — W-MUST 2012, also in CCR
• Trying Broadband Characterization at Home — PAM 2013
• Dasu: Pushing Experiments to the Internet’s Edge — NSDI 2013
• Experiments at the Internet’s Edge with Dasu — NSDI 2013 (demo)
• Characterizing Broadband Services with Dasu — NSDI 2013 (demo)
• A Measurement Experimentation Platform at the Internet’s Edge — IEEE/ACM Transactions on Networking, 2015

Coverage

Ars Technica covered our analysis of BitTorrent usage during the 2011 Japanese earthquake and the Internet shutdowns in Egypt and Libya.

People

Lead & PI

• Fabián E. Bustamante (Northwestern University)

Students

• Mario A. Sanchez
• John S. Otto
• Zachary S. Bischof
• David R. Choffnes

Collaborators

• Balachander Krishnamurthy (AT&T Labs–Research)
• Walter Willinger (AT&T Labs–Research)

Related Links

• Measurement and Experimentation from the Edge — the wider thread this belongs to
• NEWS — the earlier system that established the approach