- OC-48 SONET links were installed in four testbeds over distances of up to 2000 km, accelerating vendor development and carrier deployment of high speed SONET equipment, establishing multiple-vendor SONET interconnects, enabling discovery and resolution of standards implementation compatibility problems, and providing experience with SONET error rates in an operational environment
- Testbed researchers developed a prototype OC-12c SONET cross-connect switch and investigated interoperation with carrier SONET equipment, and developed OC-3c, OC-12, and OC-12c SONET interfaces for hosts, gateways and switches, with these activities providing important feedback to SONET chip developers
- Techniques for carrying variable-length packets directly over SONET were developed for use with HIPPI and other PTM technologies, with both layered and tightly coupled approaches explored
- An all-optical transmission system was installed and used to interconnect ATM switches over a 300 mile area using optical amplifier repeaters, and was the first carrier-based service deployment of this technology
- HIPPI technology was used for many local host links and for metropolitan area links through the use of HIPPI extenders and optical fiber; other local link technologies included Glink and Orbit
- Several wide area striping approaches were investigated as a means of deriving 622 Mbps and higher bandwidths from 155 Mbps ATM or SONET channels; configurations included end-to-end ATM over SONET, LAN-WAN HIPPI over ATM/SONET, and LAN-WAN HIPPI and other variable-length PDUs directly over SONET
- A detailed study of striping over general ATM networks concluded that cell-based striping should be used which can be introduced at LAN-WAN connection points, in conjunction with destination host cell re-ordering and an ATM-layer synchronization scheme
Transmission technology was fundamental to the establishment of the gigabit testbeds. The emergence of SONET/SDH standards for high speed transmission over wide area optical fiber in the late 1980s, and of HIPPI for local high speed connectivity in the same time frame, provided an opportunity both to construct experimental testbed facilities using prototype equipment and to accelerate that equipment's path to successful use in operational networks.
While SONET and HIPPI were the dominant transmission technologies used in the testbeds, other technologies were also used. These included wide area all-optical links using optical amplifier repeaters and new local area gigabit technologies such as Glink, which became available during the course of the project.
An important research focus in this area was the exploration of striping techniques to derive gigabit user rates from multiple lower-speed SONET channels. This was necessitated by the fact that most of the early SONET equipment available to the testbeds provided only 155 Mbps user ports -- however, striping was also pursued as a research topic in its own right, since the aggregation of multiple lower speed network channels to achieve higher bandwidths becomes increasingly attractive as user data rate requirements increase and multichannel technologies such as all-optical WDM are introduced.