October 1998

Isaac Elliott On IPDC

On August 5, the Technical Advisory Council (TAC) announced the release of technical specifications for a new protocol suite designed to bridge current circuit-based public switched telephone networks (PSTN) and emerging Internet Protocol (IP) based networks. This protocol suite is known as IPDC.

The following is a result of a discussion of that announcement with Isaac Elliott, TAC Chairman and Senior Director of Voice Network Engineering for Level 3 Communications.

I'd like to thank David Powers of Level 3 Communications for his assistance in facilitating this interview.
-Greg Galitzine, Executive Editor

IT: What is the IPDC?

IE: The Internet Protocol Device Control is a protocol suite designed to bridge current circuit-based public switched telephone networks (PSTN) and emerging Internet Protocol (IP)-based networks.

IT: What is the significance of the IPDC?

IE: Internet technology is recognized as the technology of the future and an enormous amount of entrepreneurial effort as well as capital -- both financial and intellectual -- is being directed here. Level 3 is building a next-generation IP network. This new protocol suite allows seamless integration between Level 3's IP-based network and the PSTN and will accelerate the development of new Internet-based products and services.

IT: Briefly discuss how the new IPDC specification addresses the following: Signaling Transport, Device Management, Media Control, and Connection Control.

IE: Signaling Transport: Using the IP Device Signaling Transport protocol, the media gateway can receive signaling from a circuit-switched network and deliver the signaling to a media gateway controller on an intervening IP network. The media gateway controller can also send signaling to a media gateway for delivery on a circuit-switched network.

Device Management: Using the IP Device Management protocol presented here, the media gateway controller can obtain status and receive notification of management events from the media gateway or between media gateways.

Media Control: Using the IP Media Control protocol, the media gateway controller can send messages to the media gateway to cause events such as tones to be generated or detected within a media stream.

Connection Control: Using the IP Connection Control protocol presented here, the media gateway controller can set up, modify, and tear down connections within or between media gateways.

IT: How will the IPDC specification impact the burgeoning Internet telephony field?

IE: The IPDC specification, along with a number of other protocol development initiatives underway in a number of forums, will help accelerate the move to a larger network framework that combines both Internet Protocol networks and the PSTN.

IT: What is the position of the ITU and/or IETF on this new specification?

IE: We have just submitted the IPDC protocol specifications to both the ITU and the IETF. The IPDC draft will be up for discussion at the IETF and ITU meetings in August and September, respectively. We are looking forward to discussing the breadth and scope of the IPDC specification within both of these organizations.

IT: What is the TAC?

IE: The Technical Advisory Council is comprised of leading hardware and software manufacturers with a charter to develop a set of technical standards to bridge between current circuit-based public switched telephone networks (PSTN) and emerging Internet Protocol (IP)-based networks. The TAC brings together leading communications hardware and software companies from across the industry. Founding members of the TAC include 3Com Corporation, Alcatel Telecom, Ascend Communications, Cisco Systems, Ericsson, Level 3 Communications, Lucent Technologies, Nortel (Northern Telecom), Selsius Systems, Stratus Computer, Tekelec, and Vertical Networks.

The TAC's work centers on defining the requirements for controlling a new generation of integrated network access servers. When implemented, the new, open, and interoperable protocol standards will enable external control and management of data communications equipment operating at the edge of emerging multiservice packet networks. The protocol will initially support voice over IP, modem dialup, and circuit interface services. Carrier-class products developed by members of the TAC, and based on the agreed protocol, are expected to be available by the end of 1998.

IT: What was Level 3's interest in and/or contribution to the publication of the new protocol?

IE: Level 3 organized the TAC. The IPDC specification was published on the Level 3 Web site.

IT: Will the new specification have any effect on Level 3's own network buildout?

IE: The IPDC specification allows us to control media gateways, or what we have termed "edge devices," on our multiservice core network. The IPDC protocol allows us to control these media gateways from software running on what we call "media gateway controllers." The media gateway controller is responsible for all of the routing and service-delivery logic that is part of a telecommunications service.

IT: What was the contribution of the other member companies?

IE: This was, from the outset, a total team effort working toward a common goal -- the IPDC specification. Each member company enlisted top engineers to join the TAC and work on the specification. They brought individual talents and expertise to the task, and in 60 days, we were able to accomplish the goal we set at the outset - publication of IPDC.

• 3Com Corporation
• Alcatel Telecom
• Ascend Communications
• Cisco Systems
• Ericsson
• Level 3 Communications 
• Lucent Technologies
• Nortel (Northern Telecom)
• Selsius Systems
• Stratus Computer
• Tekelec
• Vertical Networks