Introduction
The goal of the Gemini project is the effective exploitation of optical technology in computer interconnection networks. The focus is on tightly-coupled multicomputer systems, but the ideas are relevant to local-area network and wide-area network systems as well. To date, optics have been used almost exclusively as a link technology. Fiber links provide high-bandwidth paths from computer to switch and between switches. The switches themselves are, however, constructed using electronics, not optics. This necessitates a high-speed optical-to-electrical (o/e) signal translation at the inputs to each switch and an electrical-to-optical (e/o) translation at each swith output. It also limits the data rate to the bandwidth supported by the electronic switch.
One aspect of the Gemini project is the inclusion of optical switching in the high-bandwidth data path from computer to computer. With optical switching, we can support an all-optical end-to-end data path, eliminating the o/e and e/o signal translation and the data rate bottleneck at the switch.
Another aspect of the Gemini project is that we are not asking optical systems to perform tasks that are more well-suited to electronic systems. We are not constructing an all-optical switching system, we are constructing a dual-technology (optical and electrical) switching system that contains an optical data path and an electrical control path. In this way, optical technology is used where it provides significant advantages (e.g., high bandwidth) and electrical technology is used where it excels (e.g., logic and control).
Historical Context
Previous optical interconnect work was focused on inverted graph topologies. The following papers document this work:
- R.R. Krchnavek, R.D. Chamberlain, T. Barry, V. Malhotra, and Z. Dittia.
``Optical Interconnect Design for a Manufacturable Multicomputer.''
In Proc. of 2nd Int'l Conf. on Massively Parallel Processing
Using Optical Interconnections,
October 1995, pp. 279-288.
- R.D. Chamberlain and R.R. Krchnavek.
``Optically Interconnected Multicomputers Using Inverted-Graph Topologies.''
IEEE Micro, 15(2):59-69, April 1995.
- R.D. Chamberlain and R.R. Krchnavek.
``Topologies and Technologies for Optically Interconnected Multicomputers
Using Inverted Graphs.''
In Proc. of 1st Workshop on Massively Parallel Processing Using Optical
Interconnections,
April 1994, pp. 255-265.
- R.D. Chamberlain and R.R. Krchnavek. ``Architectures for Optically Interconnected Multicomputers.'' In Proc. of IEEE Global Telecommunications Conf., December 1993, pp. 1181-1186.
Funded Activities
We are funded by NSF to build a prototype all-optical data path as a proof-of-concept for the Gemini interconnect design. We are using lithium niobate electrooptical switching elements and interconnecting them using polymer waveguides. The following publications describe various aspects of the work:
- Roger Chamberlain, Mark Franklin, and Ch'ng Shi Baw,
"Gemini:
An Optical Interconnection Network for Parallel Processing."
IEEE Transactions on Parallel and Distributed Systems,
13(10):1038-1055, October 2002.
- Ch'ng Shi Baw, R.D. Chamberlain, and M.A. Franklin,
``Fair Scheduling in an Optical Interconnection Network.''
In Proc. of 7th Int'l Symp. on Modeling, Analysis, and Simulation of
Computer and Telecommunications Systems,
October 1999.
- Ch'ng Shi Baw, R.D. Chamberlain, M.A. Franklin, and M.G. Wrighton,
``The Gemini Interconnect: Data Path Measurements and Performance
Analysis.''
In Proc. of the 6th Int'l Conf. on Parallel Interconnects,
October 1999, pp. 21-30.
- R.D. Chamberlain, M.A. Franklin, R.R. Krchnavek, and B. Baysal.
``Design of an Optically-Interconnected Multicomputer,''
In Proc. of 5th Int'l Conf. on Massively Parallel Processing Using
Optical Interconnections,
June 1998, pp. 114-122.
- W.A. Castellano, R.D. Chamberlain, and R.R. Krchnavek, ``Optical Switching System for MPP, LAN, or WAN Systems.'' In Proc. of the 1997 IEEE Pacific Rim Conf. on Communications, Computers and Signal Processing, August 1997, pp. 260-264.
Follow-on Optical Work
After completion of the NSF grant, we continued work in the optical interconnect area for a period of time. The following publications describe this later work:
- Roger Chamberlain, Mark Franklin, Praveen Krishnamurthy, and
Abhijit Mahajan,
"VLSI
Photonic Ring Multicomputer Interconnect: Architecture and Signal Processing
Performance."
Journal of VLSI Signal Processing, 40(1):57-72, May 2005.
- Roger D. Chamberlain, Jason E. Fritts, Praveen Krishnamurthy,
and Hui Zhang,
"Experimental
Federated Modeling of an Optical Data Path."
In Proc. of the 4th IASTED Int'l Conf. on Modelling,
Simulation, and Optimization,
August 2004, pp. 264-274.
- Praveen Krishnamurthy, Mark Franklin, and Roger Chamberlain,
"Dynamic
Reconfiguration of an Optical Interconnect."
In Proc. of the 36th Annual Simulation Symp.,
April 2003, pp. 89-97.
- Roger D. Chamberlain, Mark A. Franklin, and Praveen Krishnamurthy,
"Optical
Network Reconfiguration for Signal Processing Applications."
In Proc. of the IEEE Int'l Conf. on Application-Specific
Systems, Architectures and Processors,
July 2002, pp. 344-355.
- Roger Chamberlain, Ch'ng Shi Baw, Mark Franklin, Christopher Hackmann,
Praveen Krishnamurthy, Abhijit Mahajan, and Michael Wrighton,
"Evaluating
the Performance of Photonic Interconnection Networks."
In Proc. of the 35th Annual Simulation Symp.,
April 2002, pp. 209-218.
- Jason Fritts and Roger Chamberlain,
"Breaking
the Memory Bottleneck with an Optical Data Path."
In Proc. of the 35th Annual Simulation Symp.,
April 2002, pp. 352-362.
- Roger D. Chamberlain, Mark A. Franklin, and Praveen Krishnamurthy,
"Performance
Evaluation of a Reconfigurable, Embedded Photonic Multiring
Interconnection Network."
In Proc. of 5th High Performance Embedded Computing Workshop,
November 2001.
- Ch'ng Shi Baw, R.D. Chamberlain, and M.A. Franklin,
"Design
of an Interconnection Network Using VLSI Photonics and Free-Space
Optical Technologies."
In Proc. of the 6th Int'l Conf. on Parallel Interconnects,
October 1999, pp. 52-61.
- N.R. Jankowski, C. Bobcowski, D. Zipkin, R.R. Krchnavek, and R.D. Chamberlain, "MEMS-Based Optical Switch Design for Reconfigurable, Fault-Tolerant Optical Backplanes." In Proc. of the 6th Int'l Conf. on Parallel Interconnects, October 1999, pp. 149-156.
People
The faculty involved in the Gemini project included:
- Roger D. Chamberlain
- Mark A. Franklin
- Robert R. Krchnavek
The students included:
- Ch'ng Shi Baw
- William Castellano
- Barak Baysal
Last modified 12 August 2006. Return to Roger's home page .
Roger Chamberlain <roger@ccrc.wustl.edu>