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Case Study: A Harmonious Relationship

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Editor's Note: This is a vendor-written case study. StreamingMedia.com accepts vendor-written case studies based upon their usefulness to our readers.

Streaming audio to millions of users takes a fast, reliable network; 10-gigabit (Gb) Ethernet service from NTT Communications helps internet radio station Pandora keep its listeners humming.

Internet radio station Pandora has a demanding audience some 16 million listeners strong. When those listeners visit www.pandora.com, they want one thing: to hear music they like. To ensure that its audience is never disappointed, Pandora Media, Inc. has to be equally or more demanding of the carriers that provide it with internet bandwidth.

And demanding it is. The network over which Pandora delivers its radio service is a model of performance and reliability, with redundant 10Gb Ethernet connections to a pair of carriers. Pandora insists that its carriers deliver connections with diverse routes to protect itself in case of a circuit outage. It even has specific router requirements for its chosen providers.

"The central charge we have is the quality of the listening experience for all of our listeners," says Steve Ginsberg, director of network engineering for Pandora. "While price is an important part of how we choose a carrier, the more important part is that we maintain that listener experience."

NTT America, Inc., the U.S.-owned subsidiary of NTT Communications (NTT Com), fit the bill for Pandora on all counts, providing a 10Gb Ethernet service that is "steady and reliable," Ginsberg says.

Music in Its Genes
Pandora launched its internet music service in 2005, but the work that went into it dates from the Music Genome Project, which began in 2000. Billed as the most comprehensive analysis of music ever, the project involved a team of 50 musicians who listened to thousands of songs and recorded details about melody, harmony, instrumentation, rhythm, vocals, lyrics, and more—as many as 400 distinct musical characteristics per song.

Figure 1
Figure 1. Pandora uses information in the Music Genome Project database to deliver music recommendations based on listeners’ preferences.

The typical music analyst involved in the project has a 4-year degree in music theory, composition, or performance and must pass a selective screening process and undergo intensive training. The result of their work is an extensive database of characteristics on nearly 100 years’ worth of music, with more being added all the time.

That database is at the heart of the Pandora experience. When listeners go to the Pandora site, they are directed first to a server cluster that runs the music database. They type in the name of a favorite song or artist, and Pandora quickly searches its database to find songs with similar musical characteristics. It then hands off the songs, in the form of URLs, to a collection of media servers that stream the songs one after another to the listener over 10Gbps internet connections, providing information on the songs and artists along the way.

Pandora launched its internet radio service using just a handful of servers and a 100Mbps internet connection. "It scaled up quickly from there," Ginsberg says. "Within six months we were adding a single gigabit line every month. From there we scaled up to 10G providers, and that’s when NTT Com entered the picture."

The NTT Com team "did a good job understanding what our requirements were and provided offerings that enabled us to do what we needed to do," he says, adding that the company also delivered a good, timely turnup of the service.

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