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Explore the fundamentals of the 21st-century intelligent network, focusing on new revenue opportunities, decreased expenses, and improved operational efficiency. Delve into optical switching and its role in optimizing network architectures, traffic engineering, and dynamic recovery. Gain insights into the benefits and constraints of hybrid computation for long-term optimization.
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The 21st Century Intelligent Network Tony Li, Carl DeSousa
Fundamentals • Profitability drives the new network • New revenues through new applications • Video telephony & conferencing • Pervasive broadband access • HDTV distribution, VOD, gaming • FTTP • Decreased expenses • Capital efficiency • Operational efficiency • Focus today on network architectures
Optical Switching: A Pragmatic Look • Optical switching can decrease switching costs • New switching layers have associated management costs • Demand from full lambda user applications is low • Greater need for optical switching in trunking
An Example • Partial mesh topologies result in transit switching • Large traffic aggregates can economically be optically switched at transit points • How can we optimally use the lambda topology? • Can we provide traffic engineering at the lambda level?
Traffic Engineering • Commonly used in telephony networks • Successful usage in IP networks with MPLS/TE • Can we extend this cleanly to the lambda level? • Inputs: • Node-to-node traffic matrix at the trunk level, time variant • Topology, capacity and costs • Desired results: (how do we set up switches) • Support current offered traffic load • Optimal assignments of lambdas to minimize global costs • Dynamic recovery to address failures
Approaches to dynamic recovery • Pre-computation • For each possible network failure, compute alternative optimal routing • Computationally intensive: scales linearly with number of elements • Does not reasonably support multiple failures • Dynamic computation • Intelligence in the network computes recovery routing • Suboptimal computation unless done with global data • Slower recovery times • Can adapt to multiple failures easily
Hybrid computation • Combine pre-computation and dynamic computation • Pre-compute most significant recovery options for single failures • Ignore low-priority recovery • Ignore multiple failures • Intelligence in the network to dynamically compute remaining cases • Centralized computation to recover global optimality for the longer term
Benefits and constraints • Smooth improvement of efficiency over time • Pre-computation provides fast recovery for covered cases • Dynamic computation provides coverage for other cases • Long term optimization eventually reaches maximal efficiency • Effective dynamic computation requires peer model optical network • IP layer must know about optical topology and capacity • Optical layer must know about traffic priorities • Overlay model abstracts optical topology & capacity