The DSL Forum - comprising more than 200 members from key DSL players, such as Verizon, BellSouth, Bell Canada and SBC - is working to improve quality of service, interoperability and the overall architecture for DSL by issuing recommendations in the form of technical reports (TRs) to the ITU, ETSI, ANSI and other standards bodies.

By building on the IETF standard for differentiated services (DiffServ) and collaborating with chip makers and CPE vendors, the organization has fostered "widespread agreement around QoS, from the access carrier network to the home," says Michael Brusca, vice president of strategy, DSL Forum Board of Directors, as well as a Distinguished Member of the Technical Staff at Verizon Communications.

"We've essentially integrated standards from various sources to develop a standardized plan for technical implementations by service providers," Brusca says. "We are specifying performance and interoperability specifications for next-gen DSL, including ADSL2 for management capabilities and ADSL2plus, which improve rate and reach, as well as VDSL for high-bandwidth packaging of services." He says that interoperability and testing plans to devise reference standards are under way at the ITU, ANSI and elsewhere.

Focused on supporting IP-based services from the CO to CPE, the DSL Forum released a suite of reports to complement TR-059, the "umbrella architecture" for its DSLHome suite of TRs. The reports are designed to help service providers prioritize the transport of IP voice, video and data according to QoS parameters, which requires a view of the CPE, set-top boxes, central office routers, transport facilities and central servers.

Focusing on advanced CPE functionality to complement the IP-based architecture in its TR-059 spec, the Forum has completed several specifications that support content delivery services such as games on demand, video on demand and videoconferencing:
TR-064 presents the LAN-side CPE specification for DSLHome. It describes CPE management capabilities that facilitate easier consumer self-installation and a new level of service management from customer locations.
TR-067 is specific to ADSL performance benchmarks and interoperability tests so that CPE in the home using different network equipment in the CO can interoperate. The methodology is now being applied to ADSL2 and ADSL2plus.
TR-068 outlines base requirements for ADSL modems with routing, to establish cross-network capabilities among multiple service providers (SPs). The Forum hopes that setting requirements for high-quality DSL modems will move such devices toward retail markets, by simplifying the process and allowing consumers to choose from a larger body of products that can be readily supported by SPs.
TR-069 is the CPE WAN Management Protocol, which has been introduced to secure CPE auto-configuration practices and incorporate other CPE management functions into a common framework. It is intended to enable a variety of service offerings, including image management, firewall, virus and spam protection, and parental control associated with home network security.
TR-092 establishes requirements for the broadband remote access servers at the CO, which communicate with routing gateways in the home.
These reports are intended to help build standards for connecting all home network devices so that voice over Internet protocol (VoIP) or even video can be extended to any monitor, TV, phone or gaming device. In addition, the Forum's TR-094 describes a networking architecture for accommodating Wi-Fi or Ethernet options as they evolve so that voice, video or data can be prioritized for QoS designations.

To continue simplifying service provisioning for customers, the Forum is coming up with a slew of new specifications for communication between the PC, modem and router during auto-configuration and initial installation. Additional work will include establishing secure connections for software downloads so that service providers can put value-added services on top of high-speed Internet connections.

That, Brusca says, should enable service providers to push anti-virus, spam-control and parental controls out to the CPE from the network, thus eliminating customer calls about viruses or pop-ups. "We set up standard communications from the CO to the CPE, so service providers can pick and choose what features of the software they want to push to DSL customers," he says.

Using the foundation of architecture and specs from the DSL Forum, other bodies will enhance standards for VoIP via DSL, IP video over DSL, on-demand services, games and music. That will bolster infrastructure that can scale and support triple and quadruple play, if interactive broadband services are to become a reality for the 100 million current DSL customers, and beyond.