All in the family, SIF demonstrates interworking at Supercomm

Like individual scraps of fabric on a quilt, the Sonet Interoperability Forum will piece together equipment from a group of members to create a demonstration showing how well interoperability can work.

The SIF demo at Supercomm, sponsored by the Alliance for Telecommunications Industry Solutions, seeks to answer unbundling and interoperability questions raised by the Telecommunications Reform Act of 1996.

SIF officials said more vendors than ever are participating, including Alcatel, Applied Innovation, Bellcore, Clear Communications, Fujitsu, Lucent Technologies, NEC, Northern Telecom, Objective Systems Integrators, Positron and Tellabs.

The network is working proof that by conforming to standards and implementation agreements interoperability testing time can be greatly shortened compared with solutions developed in proprietary domains, according to Don Thorp, SIF president and manager of Sonet network platforms for Ameritech. The disparate Supercomm network was brought to full interoperability on both traffic and data protocols in just a few weeks, and without any major product changes or large scale testing, he said.

The network itself consists of an OC-3 unidirectional path switched ring with network elements from seven different vendors and seven separate management systems (see figure). A data protocol bridge is also being used in the demo to connect network elements to some parts of the management system. All network elements will interwork at the Sonet traffic level and will conform to data communications channel protocols.

The demonstration will highlight three elements necessary for Sonet interoperability: traffic, routing and applications.

While traffic interoperability is relatively simple and has been accomplished between two systems, the Supercomm network goes beyond what has been accomplished to date, Thorp said.

The second element necessary for interoperability - control message routing - is essential for service providers to profit from Sonet's ability to reduce operations costs, he said. Sonet routing is accomplished by three network layer protocols - ISO 8473, ISO 10589, and ISO 9542.

Collectively, the three protocols exchange routing information and data transfer by automatically determining the best route to destinations on the networks, handling link failures, node failures and traffic re-routing.

The final part of interoperability shown in the demonstration involves applications that provide ways to manage networks more cost effectively through centralization. This demonstration includes the most mature applications used in Sonet, TL1 provisioning and alarm retrieval.

A real network scenario probably wouldn't include seven different network elements on a single ring, but the issues would be similar in simpler single- or multiple-ring layouts, Thorp said.