Allied Telesyn last week unveiled DSL access multiplexers that are based on IP and Ethernet, and specifically designed for "triple-play" applications: video, voice and data over one broadband connection.

The company's 7700 and 7400 DSLAMs are designed as a less expensive and more versatile alternative to ATM-based DSLAMs. They also are targeted predominantly at independent operating companies (IOC) that are more bullish than incumbent local exchange carriers (ILEC) when it comes to providing triple-play services over DSL broadband connections.

By offering triple-play services over existing copper, IOCs have a carrot with which to retain customers attracted to the data offerings of satellite and cable companies. These services are also looked upon as a way to reverse declining voice revenue.

To aid in this effort, the 7000-series DSLAMs are optimized for delivery of video over asymmetric DSL (ADSL). They can support IP multicasting of up to 512 video channels via an Internet Group Multicast Protocol (IGMP) snooping, parsing and correlation technique Allied Telesyn developed.

This technique, which identifies and delivers video streams on a per-port basis, is designed to scale IGMP and avoid flooding the network with multicast requests, Allied Telesyn says.

"This was one of the main considerations" for selecting the 7000 series, says Richard Kenshalo, director of engineering, construction and operations of Matanuska Telephone Association in Palmer, Alaska. "It's essential for what we're trying to deliver."

Matanuska evaluated IP DSLAMs from AFC, Cisco, Net2Net and Next Level Communications before deciding on Allied Telesyn. Kenshalo expects a 60% to 70% penetration rate of its digital television service into its subscriber base of 35,000.

In addition to Matanuska Telephone, the 7000-series DSLAMs are deployed by Midwest TelNet, a consortium of IOCs in Wisconsin that services 22,000 subscribers; and Vernon Telephone Cooperative of Westby, Wis.

"The IGMP switching request has got to be handled at the port-access edge due to latency concerns," Kenshalo says. "It's one of our critical design criteria. Otherwise, you kill your network. People are used to seeing something happen when they change the channel."