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Comcast's Road to 20 Billion VOD Views(Multichannel News Via Acquire Media NewsEdge) THREE YEARS AGO, COMCAST WAS DELIVERING video-on-demand essentially the same way McDonald's serves burgers or Starbucks whips up lattes: locally, out of dozens of locations across the U.S. The operator had to shift to a centrally managed, hierarchical distribution model after deciding it wanted to give subscribers access to tens of thousands of VOD selections with a vision of hitting 100,000 and beyond. Back in January 2008, Comcast CEO Brian Roberts outlined “Project Infinity” in a keynote at the Consumer Electronics Show. Among his promises: 1,000 high-definition titles on-demand by the end of the year, and eventually a virtually limitless selection of video entertainment. Meeting that initial target required some heavy lifting, given the isolated nature of Comcast's VOD infrastructure at the time. “That was about adding more storage in literally 130 locations to get to 1,000 HD choices,” John Schanz, Comcast executive vice president of national engineering and technical operations, said. Today, the operator's distributed VOD architecture looks similar to an Internet content delivery network, or CDN. Like its Internet counterparts, the Comcast CDN for video, dubbed CCDN internally, stores all content on large-scale “library servers” and stores cached copies closer to subscribers based on the popularity of the content. ‘WORK AS A TEAM’The project involved linking those 130 “islands” of VOD servers, now down to about 90, into a nationwide network fed by the library servers in four regional locations. In the middle are about 100 mezzanine gateways that cache VOD assets and manage the content that is distributed to the edge servers. “We have unified those islands in a single operating platform, monitored in our network-operations center,” Comcast senior vice president of product engineering Mark Muehl said. “We have taught them to work as a team.” Most of the CDDN upgrade was executed without downtime. About 10% of the work required taking VOD servers offline, which was done in early-morning service windows to minimize the disruption for customers. “In some sense, this is a living organism.” MARK MUEHL, COMCAST The CCDN project has been like “literally rebuilding an aircraft carrier as it's landing planes,” Muehl said. Schanz added: “Sometimes, in deploying anew technology, you are forgiven with low usage in a greenfield environment. But we were stepping into the highest-scale VOD environment in the world.” Comcast now offers 30,000 VOD choices in markets served by the CCDN, compared with 740 when it first launched video-on-demand service in 2003. The CCDN serves about 80% of the operator's footprint. The architecture has helped push up the amount of content subscribers watch Comcast announced in May that it had surpassed 20 billion VOD sessions to date. Moreover, with additional content and better search features, Comcast subscribers are watching a greater variety of content. “We're seeing a longer tail,” Muehl said. And the CCDN architecture is “horizontally scalable,” Muehl said, meaning it really is capable of delivering an ever-expanding number of videos as long as there's enough bandwidth and storage to deliver them. “As we add more content to the library, there are different parts of the service we need to scale up,” he said. “In some sense, this is a living organism.” NEXT-DAY DELIVERYThe centralized nature of the CCDN has allowed the operator to update VOD content more quickly. For example, Comcast now offers TV episodes of popular shows from the four major broadcasters the day after they air, after reaching deals with Fox and ABC earlier this spring. The CCDN also enabled Comcast's launch of dynamic VOD ad insertion this summer in 17 markets, representing about 7.4 million subscribers, by providing a centralized means to distribute the ad assets. Comcast declined to specify the vendors of the hardware and software it used to build the CCDN. Schanz noted, however, that the VOD back-end is based on multivendor, open standards. Cisco Systems is now Comcast's primary VOD server vendor, according to several industry sources. The operator has removed SeaChange International's VOD servers from the production environmentbecause they did not fit well into the hierarchical CCDN architecture, but Comcast still uses the vendor's back-end management software, sources said. SeaChange declined to comment except to say the company “continues to have a very strong relationship with Comcast, particularly for software and the associated hardware.” Another component of Comcast's revamped VOD service is the UDB the Universal Database. That software provides a comprehensive catalog of all on-demand assets, with the associated metadata. Comcast publishes information about individual VOD assets once, and that metadata is distributed to about 100 UDB servers around the country. When a Comcast customer navigates through the VOD menu on TV, or does a search for shows or movies on Xfini-tyrv.com or the iPad and iPhone apps, the query is handled by one of those UDB servers. The Universal Database system processes 200 million menu navigations daily, Muehl said. The UDB software was developed by Comcast, whereas the operator worked with various vendors for the hierarchical caching and content management functions of the CCDN. The CCDN's first application is video-on-demand, but Comcast execs said it could be extended to others, such as a network-based digital video recorder service. The MSO expects to conduct a small test of the network DVR concept this year but has not announced any commercial plans for such a service. “It's a platform,” Schanz said of the CCDN. “It's optimized for video, and ultimately I think of it as our platform for anything time-shifted.” BACK END OF INFINITY Details on the Comcast CDN: Architecture: All VOD content stored in library servers at four regional data centers, with the most popular titles cached on edge servers in 90 locations. Library server locations: Philadelphia, Atlanta, Chicago and San Francisco Storage: 150 Terabytes of usable disk space in each library server (enough to hold roughly 64,000 hours of SD or 16,000 hours of HD MPEG-2 video). Video-on-demand lineup: 30,000 titles in CCDN-enabled markets. Deployment: Just over 80% of Comcast's footprint. SOURCE: Comcast 2011 International Press Telecommunications Council |