4.2 Switching

Summary

• Prototype high speed ATM switches were implemented and deployed for experiments in several of the testbeds, supporting 622 Mbps end-to-end switched links using both 155 Mbps striping and single-port 622 Mbps operation
• First telco central office broadband ATM switch was installed and used for testbed experiments, using OC-12c links to customer premises equipment and OC-48 trunking
• Wide area variable-length PTM switching was developed and deployed in the testbeds using IBM's Planet technology and through the use of HIPPI switches in conjunction with collocated wide area gateways
• Both ATM and PTM technologies were developed and deployed for testbed local and desk area networking experiments, along with the use of commercial HIPPI and ATM switches which became available as a result of testbed-related work
• A TDMA technique was developed and applied to tandem HIPPI switches to demonstrate packet-based QoS operation in HIPPI circuit-oriented switching environments, and a study of preemptive switching of variable length packets indicated a ten-fold reduction in processing requirements was possible relative to processor-based cell switching

Several different experimental wide area switches and newly developed local area switch products were used in the testbeds. In addition, as part of achieving overall testbed research objectives, new system-level approaches to gigabit network switching were explored for achieving Desk Area Networking, local and wide area flexible HIPPI switching, and the relaxation of switching rate requirements based on pre-emptive techniques.