A Bandwidth-Efficient and Low-Latency Packet Assembly Strategy for Optical Burst Switching in Metro Ring

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A Bandwidth-Efficient and Low-Latency Packet
Assembly Strategy for Optical Burst Switching in
Metro Ring Prasanna Krishnamoorthy, Andrea
Fumagalli Optical Networks Advanced Research
(OpNeAR) Lab., Erik Jonsson School of EECS,
University of Texas at Dallas
Burst Switching
LightRing Architecture
LightRing Advantages

• Packets from a flow same source, destination
  and class are aggregated to make bursts
• These bursts, are transmitted all-optically
  through the core of the network
• Benefit
• Lower overhead
• Allows slower optical switching speeds

• No loss
• In lossy Burst switching networks, larger bursts
  cause higher packet loss probability
• LightRing is lossless, hence we can build bigger
  bursts
• Ring topology
• Since path and intermediate nodes are known,
  aggregation can be done across multiple
  destinations

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• Ring topology
• Multi-wavelength
• All-optical
• Token-based access protocol
• Loss-free, bandwidth on-demand
• Spatial Reuse

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Node Architecture
Optical Burst Add Drop Multiplexer (OB-ADM)
Aggregation Protocol
QoS Protocol

• Different aggregation possibilities
• Same source, destination and class (S/D/C)
• Same source, destination, different classes (S/D)
• Same source, different destinations and classes
  (S)
• Aggregating different packet flows provides even
  better bandwidth efficiency
• more packets travel on the same burst
• number of burst requests go down
• latency goes down due to many flows being
  multiplexed
• Larger bursts can be created quicker due to
  lossless nature of LightRing !

• Source OB-ADM node
• receives packets from external connection.
• aggregates packets into a burst
• transmits bursts all-optically to destination
• Destination OB-ADM
• de-multiplexes the packets from the burst
• transmits out of the network

• Token has a counter
• Counter keeps track of outstanding real-time
  traffic at all the nodes
• If counter increases, then best-effort traffic is
  not allowed onto the ring
• Only if counter decreases, best-effort traffic is
  allowed onto the ring

Response Time Vs Throughput
Variation with Ring Size
a/D with Varying Load
Summary

• Lossless transmission allows greater efficiency
  since each burst can be larger
• Ring topology intermediate nodes are known
  allows same burst to have packets for different
  destinations
• Larger bursts more efficient (less overhead)
• Since more flows are used, bursts can be built
  quicker lower latency

16 Nodes, 4 x OC-192, 80km
16 Nodes, 4 x OC-192
16 Nodes, 4 x OC-192, 80km