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Explore the importance of optical networking for future networks, covering dynamic routing, cross-layer design, and programmable features. Learn about the research efforts at Columbia University and the challenges addressed through simulations and experimental demonstrations.
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Creating a Future Internet Network Architecture with a Programmable Optical Layer Keren Bergman Columbia University
Motivation • Today’s optical WDM networks…deliver • Sufficient power margins for high physical-layer reliability, • “Error-free” (bit error ratios < 10-15) data links • Small link outage probabilities (10-4 to 10-8) • “Black-box” reliable transport performance (So why should we care… about the optical physical layer in FIND?)
Motivation – Why should we care? • Future optical networks will need to support… • mixed bit-rates… >100G • different, co-existing modulation formats • alien wavelengths • dynamic optical routing, • packet, circuit switched • cross-layer optimization • … • Increase in network flexibility calls for relaxed physical layer performance constraints
Network Routing Layer Cross-layer architectural design with programmable optical layer Application and Services Driven Layer Cross-Layer Information Exchange • Future optical networks with inherently flexible margins • Resilience to impairments through dynamic protection • Support QoS aware protocols, cross-layer optimization,… • Architecture design exploration incorporating dynamically programmable optical layer • Optical layer becomes an accessible component for dynamically optimization Dynamically Programmable Optical Physical Layer
FIND Research Effort at Columbia Our efforts include simulation validation and experimental demonstrations: • Simulations: development of realistic physical layer models into packet networking simulation environment (ns-2) • Experimental demos: dynamically programmable optical layer to realize impairment aware routing • Project provides new framework for bridging the gap between FIND endeavors and underlying heterogeneous substrate • Engaging with networking research community to develop platform into broader FIND architectural vision
Optical packet networks simulation • To address this challenge…network simulators should incorporate: • Dynamic physical-layer performance variations • Data traffic dynamism • Cross-layer communication based protocols • Physical-layer performance variations can be modeled via bit-error ratio fluctuations: • Deduced from impairment simulations or measurements • Impairments: • ‘Quasi-static’: loss, chromatic dispersion, … • Moderately fast: polarization variations, PMD, … • Highly dynamic impairments: power transients, crosstalk, …
Time-scale BER variations • Packet-by-packet BER variations: Most physical-layer • impairmentsslow compared to packet duration. • Intra-packet BER variations: Can be found even for slow • variations if packet is transported on a TDM infrastructure.
NS-2 packet simulator modules • NS-2: Open-source discrete-event packet network simulator • Newly developed software modules enabling cross-layer • simulations beyond existing modules: • BER variations • Error correction/ • error detection • Local control plane http://groups.geni.net/geni/wiki/Embedded Real-Time Measurements
Experimental programmable optical physical layer …broadband multicasting Experimental demonstration: • Multicasting on dynamically programmable optical switching fabric • Application for impairment aware routing via cross-layer communications Broadband (multi-wavelength) Multicasting: • Multicast broadband, wavelength-striped optical messages • Message-by-message granularity • To drive emerging high bandwidth applications: • Computing • Streaming video • Gaming • …
Experimental Multicast-Capable Fabric SPINet N2
Experimental Multicast-Capable Fabric • Pattern of optical packets injected in 2 networks • Straightforwardly supports multicast and unicast • Error-free transmission (bit-error rates<10-12) of 8×10 Gb/s wavelength-striped payloads with power penalty < 1 dB • Data rate scalability: error-free transmission of 6×40 + 1×10 Gb/s (mixed data rates) • Unicast on SPINet • Unicast on N2 • Multicast from single source • Multicast from multiple sources