LightRing%20with%20Tunable%20Transceivers

1
LightRing with Tunable Transceivers Kalai Rajah
Narayanan Optical Networks Advanced Research
(OpNeAR) Lab The University of Texas at Dallas
LightRing Architecture
Node Architecture
Characteristics of LightRing

• 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 transmitters
• 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

N32, W16, R16, T16, ? 0, Ring. Lat
400µsec
N32, W16, RT16, a/D3, Ring. Lat 400µsec
N32, W16, R16, T16, a/D3