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Explore dynamic configurations, wavelength assignments, and optimization challenges in optical networks. Learn about efficient wavelength allocation and bandwidth utilization to design robust network infrastructures.
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Notes on Optical Networks Jean WalrandEECS
Outline • Dynamic Configuration? • Wavelength Assignment • Too Much Bandwidth?
Dynamic Configuration? • Consider IP/ON:
Dynamic Configuration? (cd) • Model: Note: Assuming TDM of the two configurations, we can get any combination of service rates that add up to 3m. However, the optimalscheduling is dynamic. In the case where the two arrival rates are equal, it is shown above. Question: How much do we gain?
Wavelength Assignment • Example 1 • N users. Each user listens to some wavelengths and transmits on others. There are W wavelengths. • N users choose among W to send and N users choose among W to receive => W2N choices. • There are N! connection matrices. • Hence W2N > N! > (N/e)N => W > (N/e)0.5 • Example: W = 160 => N < e(160)2 = 70,000.
Wavelength Assignment (cd) • Example 1 (cd) • Constructing a network to achieve this bound: Full broadcast. • However, this is not practical. Introducing constraints limits N.
Wavelength Assignment (cd) • Example 2 • Selecting wavelengths: Greedy: lowest from L to R 1 3 1 2 2 Note: For general networks, a greedy algorithm is not optimal. In fact,an optimal algorithm is known to be NP hard.
Too Much Bandwidth? • Assumptions: • 84M houses • 20Mbps incoming, 2Mbps outgoing / house • Assume 80% incoming traffic is coming from local server, rest from anywhere • Outgoing traffic goes anywhere • Problem: • Design a network: switches, links, …
Too Much Bandwidth? (cd) • Rough attempt: • 12 metro areas of 7M houses each • Into each area: 11/12 of 4Mbpsx7M = 26Tbps • Questions: • Include multicast model • Design network (optical core + routers)