Physical Infrastructure

ATDnet is supported with a physical infrastructure provided by Bell Atlantic, a regional Bell Operating Company (RBOC). Funded by DARPA, a contract was awarded to Bell Atlantic in November 1993 following a competitive solicitation via DARPA Broad Area Announcement BAA 93-02, Multiple-Technology Network Testbed. The base period two year award was $1.9 million per year and a two year optional extension is offered at $1.4 million per year.

The SONET/ATM network testbed employs a physical ring topology for SONET transport among the six Government sites. ATM switching connectivity will be evaluated in multiple configurations, including a logical star topology and a ring configuration paralleling the SONET ring.

Bell Atlantic is provisioning ATDnet as a diversely routed, survivable SONET ring with SONET add/drop multiplexers (ADM) installed at the customer premises and at Bell Atlantic's Operations Support Center in Silver Spring, Maryland. The SONET ring is initially configured with two fibers.

Northern Telecom Inc. S/DMS OC-48 Transport Nodes serve as the ADMs. Each OC-48 ADM complies with SONET standards to transport high capacity data streams of up to 2.5 Gigabits/second over fiber optic media. The S/DMS OC-48 can route service and protection lines over physically and geographically separate facilities and can sense and automatically restore interrupted service.

Each Government site will be provisioned with two-fiber, OC-48 SONET service to its ADM. Such a facility is referred to as a Metropolitan Point of Presence (MPOP). Initially, each on-site MPOP will be further provisioned with two OC-3c (155 million bits/second) service connections to on-premise, Government- furnished ATM switches. Deployment of OC12c (622 million bits/second) ATM services is expected in 1995.

In ATDnet Phase I, FORE Systems FORErunner ASX-100 switches will be employed at every site. Deployment of ATM resources from other vendors is planned, using standards-compliant signaling, to experimentally validate interoperability and potential for national-scale, switched virtual circuit (SVC) public ATM environments.

On-premise routing and local distribution of ATM and SONET traffic is the individual responsibility of each participating agency. Typical configurations may include ATM service to scientific/engineering workstations, database and file servers, high performance computers, and high resolution and 3D display devices.