San Antonio’s Big Conversion


The engineers at Time Warner Cable’s San Antonio system had a busy summer. The system switched out its video-on-demand server gear, going from servers in 28 hub locations to two servers in two redundant locations, while implementing dense wave division multiplexing (DWDM) and installing an Internet protocol transport platform.

The move from SeaChange International Inc. to Broadbus Technologies servers is estimated to be one of the larger switchouts to date in the U.S.

Coordinating hardware and software, ingesting content, and making the final cutover service group by service group, was not necessarily an easy task, but one that was completed with any major hitches for the system’s 150,000 digital subscribers, according to Time Warner and Broadbus executives.

The MSO began looking to upgrade its VOD hardware in early 2004, according to Norrie Bush, vice president of engineering for Time Warner’s San Antonio division. VOD was evolving to the point that Time Warner felt the need to separate streaming from storage, he said, because streaming needs were growing much faster than storage requirements.

To accomplish that would have required a forklift upgrade of the legacy VOD gear, he said. “We started looking at next-generation technology,” Bush added, as well as possible changes in the core distribution network.

In the end, Time Warner decided to upgrade three elements. “We installed a DWDM fiber network to increase bandwidth,” Bush said. “We built a Cisco [Systems Inc.] switched-IP network on top of that to provide IP connectivity between all 28 hubs. We then looked at the VOD technology and decided to go with Broadbus.”

Time Warner was attracted to Broadbus because of its ability to separate streaming and storage. It can add streaming without adding storage. “We see streaming growth happening a lot faster than storage growth,” he said. “It also gives you the ability to centralize storage, which may not be collocated with streaming engines.”

Time Warner installed two Broadbus, DRAM-based (dynamic random access memory) servers to two different locations in the city. “We designed the network so that we would be able to stream to all hubs from any server,” Bush said. Each Time Warner hub passes 20,000 to 40,000 homes, Bush said.

The original SeaChange servers were deployed in those 28 hubs. Some consolidation in 2003 brought that figure down to five server locations.

For Broadbus, job one in the conversion was replicating the content. “The first thing is you have to be able to capture all of the content available, and that process takes time,” president Jeff Binder said. The content is a mix of nationally delivered, plus locally encoded content, which is being continuously refreshed.

“Once you secure the content, you have to make the network and interfaces ready,” Binder said. “Then it’s a service-group-by-service-group cutover process.”

The plan was to complete the cutover in 60 days, “but after we got a few days into it, they were so happy, we accelerated the time schedule down to 30 days.”

Part of the cutover involved changing VOD server outputs and inputs to Gigabit Ethernet, Bush said. “We built all GigE circuits out to the hubs,” he said.

During the actual service group cutover, “we had to have someone in the hub and at the servers,” he added. “We already had the Broadbus servers running side by side. We had to install GigE to ASI conversion equipment at the hub.”

Save for a few early glitches that were correctable, the cutover went smoothly, Bush said. If a subscriber was watching a VOD stream in the middle of the night when conversions took place, the screen might temporarily freeze or stop. Hitting the “play” button would then resume the VOD stream.

San Antonio is one of 20 “cutover” markets that Broadbus is involved in. The company has deals with Comcast Corp., Time Warner, Charter Communications Inc., Adelphia Communications Corp. and Rogers Cable Inc.

In speaking of the San Antonio conversion, Vin Bisceglia, chairman and CEO of Broadbus said: “We did it without interruption. I think we have cracked the code on how to build next-generation video servers.”

Besceglia said Broadbus recreates each cutover environment in its labs, to test for trouble spots before going into the field. “It is our insurance policy,” he said. The lab can handle more than 100,000 VOD streams.

Binder reports there were no major integration issues, with Time Warner’s Nortel Networks backbone of the Scientific-Atlanta Inc. set-tops. “That’s the beauty of ISA [Time Warner’s interactive services architecture],” he said.

For Time Warner, the stage is set for further VOD growth. Bush said 90% of digital set-tops stream VOD in a given month in San Antonio, much higher than the industry average. “We’re experiencing tremendous usage of the product,” he said.

His free advice on cutovers? “Do as much prior planning as possible. You can do specific steps that will head off most of the major problems. The support we’ve gotten from Broadbus in the deployment has been a major plus for us.”