LightRing with Tunable Transceivers Kalai Rajah Narayanan

1. LightRing with Tunable Transceivers Kalai Rajah Narayanan Optical Networks Advanced Research (OpNeAR) Lab The University of Texas at Dallas l1 l2 l3 4 3 5 2 6 1 7 8 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 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) Summary Throughput vs. a/D 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