LightRing with Tunable Transceivers Kalai Rajah Narayanan Optical Networks Advanced Research (OpNeAR) Lab The University of Texas at Dallas LightRing Architecture Characteristics of LightRing Node Architecture Advantages Contention free, on-demand bandwidth allocation Token based – provides simple control approach Destination stripping of messages Frees resources after usage Limitations Number of transceivers increases in the order of the wavelengths  increase in cost, scalability issues Message sizes have to be large (compared to ring latency) to achieve high efficiency All-optical Ring topology Multi-wavelengths Token-based access protocol Loss-free Bandwidth on-demand Spatial Reuse l1 l2 l3 1 2 3 4 5 6 7 8 Tunable Transceivers Transmitter Tuning Strategy Receiver Tuning Strategy Tuning Strategy Extensions Pre-calculated tuning: Transmitter tuned before appropriate token arrival at node Parallel tuning of transmitters Runs as background process Performance improvement with higher number of transmitters Reservation-based Tuning: Transmitters tuned after token arrival at node Small overhead – tunes only when necessary Performance improvement with less number of transmitters Reduce transmitters and receivers at nodes Efficient tuning algorithms With reduced overhead Adjustable with traffic flow Distributed and distinct algorithms for transmitters and receivers Tokens used as receiver status indicators No extra control overhead Transmitter tuning strategies can be: Chosen flexibly according to network parameters Applied to bi-directional rings with cross-signaling or independent signaling Extended to accommodate band-limited tuning Used with varied Transmitter/ Receiver node configurations Idle receiver follows busy transmitter’s wavelength Receiver tuning overlaps with signaling latency Receiver status is advertised through tokens Only one receiver is tuned during one token arrival at a node (computationally less intensive) Throughput vs. a/D Summary Throughput vs. Tuning Time Analytical vs. Simulation Results LightRing features still preserved Transmitters and receivers can be reduced without affecting performance significantly Tuning strategies take advantage of ring latency Tuning algorithms can be run individually for transmitters and receivers Algorithms are simple, distributed Algorithms work under non-uniform traffic and are extensible to bidirectional rings, band-limited tuning N=32, W=16, R=16, T≤16,  = 0, Ring. Lat = 400µsec N=32, W=16, R=T≤16, a/D=3, Ring. Lat = 400µsec N=32, W=16, R=16, T≤16, a/D=3