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ECSE-6660: Broadband Networks Exam 3: Comprehensive. Time: 120 min (strictly enforced) Points: 100 YOUR NAME: Be brief, but DO NOT omit necessary detail
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ECSE-6660: Broadband Networks Exam 3: Comprehensive Time: 120 min (strictly enforced) Points: 100 YOUR NAME: Be brief, but DO NOT omit necessary detail {Note: Simply copying text directly from the slides or notes will not earn (partial) credit. Brief, clear and consistent explanation will.}
I. Quick True/False Questions: (16 points) Tick True or False (1 pt each). Add a 1 line explanation JUSTIFYING your choice (1 pt each) T F Long-period and short-period fiber gratings both behave as Bragg gratings 1R regeneration performs the same function as all-optical amplification Lasers work on the principle of spontaneous emission of radiation Spectral width of lasers is the same as its line width
Tick True or False (1 pt each). Add a 1 line explanation JUSTIFYING your choice (1 pt each) T F NHRP is intended for making ATM run over Ethernet Diff-serv is a connectionless and stateless QoS architecture Delta modulation is an example of a vocoder SIP uses a gatekeeper to make phone calls to email addresses
II. (12 pts) Explain the economic and technical rationales for the following technology transitions: a) T-carrier hierarchy to Survivable SONET/SDH [4 pts] b) SONET to (D)WDM [4 pts] c) WDM to Optical Transport Networks (OTNs) [4 pts]
III. (12 pts) A. (6 pts) Define the meaning of the following terms: a) Modal dispersion, b) Chromatic Dispersion c) Four Wave Mixing B.(6 pts) Describe the ways and exactly how (eg: optical components, fiber innovations) the above technical problems were solved in optical communication:
IV. (12 pts) What are the fundamental technical (not functional!) differences between: a) Optical amplifiers (eg: EDFA) b) Lasers c) LEDs d) Fabry-Perot etalons used for filtering e) P-I-N Photodetectors
V. (12 pts) What are the key differences between the following survivability techniques: Linear APS, UPSR, 2-fiber BLSR and 4-fiber BLSR [6 pts]. Where are these techniques typically deployed in today’s broadband networks [2 pts]? Why are these techniques deployed in these places [2 pts]? Describe how mesh-based survivability differs from these methods in terms of techniques and objectives? [2 pts]?
VI. (12 pts) Describe the differences between the following forms of QoS scheduling: priority, round-robin, GPS, bit-by-bit round-robin, and weighted fair queuing scheduling
VII. (12 pts) Describe the key differences between QoS routing (eg: PNNI), traffic engineering (eg: MPLS, BANANAS) and regular IP routing (eg: OSPF, BGP)
VII. (12 pts) SONET OC-48 line cards cost $25K ea, whereas IP/SONET OC-48 line-cards cost $100K ea. The primary reason is the complexity of IP lookup and scheduling/buffer management implemented in ASIC/FPGA/network processors. Describe WHY IP lookup and scheduling/buffer management are so complex [8 pts]. Also describe the key tradeoffs in the choice of ASICs vs network processors [4 pts].