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Enhancing the Traffic Carrying Capacity of Optical Networks. Pramode K. Verma pverma@ou.edu Telecommunications Systems Program The University of Oklahoma – Tulsa. The Global Landscape. $1.2 trillion industry in 2002 Unsustainable rates of network deployment at the turn of the century
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Enhancing the Traffic Carrying Capacity of Optical Networks Pramode K. Verma pverma@ou.edu Telecommunications Systems Program The University of Oklahoma – Tulsa June, 2004
The Global Landscape • $1.2 trillion industry in 2002 • Unsustainable rates of network deployment at the turn of the century • $1.7 trillion loss in the market value of the industry • Selling phone service is not a sustainable business any more! June, 2004
Outline • Traditional Telecommunication Systems • Optical Switching Technologies • Problems in Optical Networks with Wavelength Routing and Assignment • Proposed Solution June, 2004
The Telecommunications Industry • A very unique industry • Driven by some very unique laws of nature • In robust health • Meltdown at the turn of the decade • Moderate (5-6%) growth anticipated in the future • Future Breakthroughs • Photonics • Wireless • Context sensitive applications June, 2004
Common User Networks (1) June, 2004
Common User Networks (2) June, 2004
Common User Networks (3) • Characteristics • Probabilistic demands for service • “under provisioned” by design June, 2004
Desired Response Carried Traffic Observed Response Incident Traffic Observed Characteristics of Telecommunication Networks (1) June, 2004
Observed Characteristics of Telecommunication Networks (2) • Design Objectives • For a given topology maximize the network throughput or served traffic • Be fair among “classes” of traffic • Designer’s Tool Kit • Accept or reject traffic at source • Control routing flexibility June, 2004
Telecommunication Networks (1) The North American hierarchical network (dashed lines show high-usage trunks). Note how the two highest ranks are connected in mesh. June, 2004
Telecommunication Networks (2) • Legacy • Circuit Switched • Hierarchical • Evolving To • EOE • All Optical Lambda • Optical Burst Switching • Optical Packet Switching June, 2004
Optical Switching Technologies Wavelength Routing And Assignment (RWA) Optical Burst Switching (OBS) Optical Packet Switching (OPS) June, 2004
Wavelength Routing and Assignment (RWA) • Set up a light-path • Issues • Routing • Wavelength Assignment • Fairness • Throughput June, 2004
Illustrative example NY WA MI NJ PA UT CA1 CO IL NE MD CA2 GA TX June, 2004
Major Results (1) • Theorem 1: For any network topology, as the incident traffic intensity increases, the carried single-hop traffic between a source-destination node pair reaches a finite limit. June, 2004
Major Results (2) • Theorem 2: For any network topology, as the incident traffic intensity increases, the carried multi-hop traffic (i.e., traffic with two or more hops) between any source-destination node-pair increases, but eventually goes to zero, after reaching a peak. June, 2004
NY WA MI NJ PA UT CA1 CO IL NE MD CA2 GA TX June, 2004
Illustrative Example: A Network with a Mesh Topology 3 2 4 1 6 5 June, 2004
The Carried Traffic of the Mesh Topology June, 2004
Impact of the Quantitative Understanding of the Network Behavior • Analytical results lead to quantification of the network performance • How do we use the new understanding to provide fairness while maximizing the network revenue June, 2004
Higher Blocking Probability for Multi-hop Traffic SLA requires a maximum threshold for probability of blocking Implications of the Threshold? Fairness Problem June, 2004
All available wavelengths shared by all traffic classes Reserved wavelengths for traffic between node si and dj Reserved wavelengths for traffic between node s1 and d1 … Shared wavelengths Reserved wavelengths for traffic between node sn and dn Incident traffic increases The Congestion Aware Wavelength Reservation Method (CAWR) June, 2004
Blocking Probability with or without the CAWR Method June, 2004
Network Revenue with or without the CAWR Method . We assume that for completed call connections, the service charge is $M/(Erlang*Hop). June, 2004
Conclusion We have shown that as the incident traffic increases, the carried multi-hop traffic reaches a peak and then drops to zero, while the carried single-hop traffic goes to an asymptotic limit. When the incident traffic intensity of the network is arbitrarily high, the network can carry only single-hop traffic. We presented an algorithm called the Congestion Aware Wavelength Reservation to resolve the fairness problem in a DWDM network with multiple classes of traffic, while at the same time maximizing the throughput of the network and its attendant revenue. June, 2004
Thanks & Question June, 2004