VOD Gateway To Provide More Streams at Less Cost

Artel is introducing the VSG (Video Session Gateway), a video-on-demand transport system based on Gigabit Ethernet that it says allows for the transport of up to 30,000 MPEG streams on a single fiber. The company also says it will reduce transport costs to around $30-$40 when it's available this fall.

"We purpose-built this system to meet MSOs' requirements that they expressed to us," says Artel Vice President, Marketing, Tony Dolph. "And we're bullish that we also picked the right price points."

The VSG is built around a network processing unit that allows Artel to flexibly scale the backpath based on the needs of the installation. "That keeps the cost down and increases the functionality," Dolph says.

Currently, the system has two components: the VSGx, a 2RU modular system that can support up to 12 Gigabit Ethernet (GbE) connections per chassis, and the VSGm, a 1RU passive Dense Wavelength Division Multiplexing (DWDM) platform that can adapt the VSG system to any network topology.

Cable operators will find the scalability of the VSGx attractive, Dolph says. Today, most operators are deploying 1- or 2-Gb transport paths, which are difficult to scale up if the take rate or channel lineup increases. VSG uses 3-Gb GbE modules, offering greater predictability in the cost-per-stream metrics.

"The 3-Gb has a very low cost per stream because we're not asking people to buy shallow bandwidth," he says. "With the 1-Gb, costs aren't reduced as bandwidth is added. And, with 8 Gb, there are very few optical nodes that need that much bandwidth for traffic. But, by scaling in 3-Gb increments, you soften out the cost curve and get better cost benefits."

The VSGx can handle up to four of the 3GbE modules and also has Layer 2 link aggregation, which Dolph says allows it to do Ethernet switching itself and link and path segregation. It can also aggregate undersubscribed ports and the output of multiple VOD servers.

The main challenge that MSOs face today is maximizing the fiber plant deployed to offer customers new and expanded services. With the 3-Gb module's ability to carry 30,000 streams on a single fiber, he believes, that challenge has been solved. "Plus VSG allows the MSO to deploy not only a solution to meet the needs of SVOD applications today but also network-based PVR in the future."

The VSGm, he explains, is the glue that allows the VSGx to work with any MSO network topology, be it ring, star, cascade or redundant ring. "We've really looked at inexpensive and reliable passive components to build out low-cost networks."

Features of the VSGm include four- and 20-channel DWDM mux/demux modules, add/drop/pass filters for ITU channels 19-59, combiners/splitters (50/50 and 80/20), four-channel band splitters for low-loss filtering of local traffic, and red/blue band-splitter filters to split forward and return path traffic.