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Slide 1: 642-321 Cisco Optical SDH Exam Exam 642-321 Demo Edition © 2005- 2006 Test Killer, LTD All Rights Reserved 1 http://www.testkiller.com http://www.troytec.com Slide 2: QUESTION 1: 642-321 For lasers with tightly controlled wavelengths, approximately how far apart are the centers of adjacent wavelengths when 100 GHz spacing is used in a DWDM system? A. 0.4 nanometers B. 0.6 nanometers C. 0.8 nanometers D. 1.2 nanometers E. 1.6 nanometers Answer: C QUESTION 2: The dispersion of a non-zero dispersion shifted fiber is 6 ps/nmkm at 1550 nm and 10 ps/nmkm at 1610 nm. What is the minimum dispersion compensation required if an L-Band DWDM signal travels through 200 km of fiber and has a dispersion of 1800 ps/nm? A. None B. -600 ps/nm C. -200 ps/nm D. +600 ps/nm E. +600 ps/nm Answer: C QUESTION 3: Exhibit: Which type of multiplexer is shown in the exhibit? A. Thin film filter B. Fiber Bragg Grating C. Arrayed Wave Guide D. Erbium fiber amplifier Answer: C 2 http://www.testkiller.com http://www.troytec.com Slide 3: 642-321 QUESTION 4: In the OSNR model for EDFA amplifier, SNRout= 1/(1(SNRIN + FhvB/PIN), what does the SNRIN represent? A. The signal to noise of the current optical amplifier. B. The signal to noise of the previous amplifier of source. C. The signal to noise introduced by the optical amplifier. D. The accumulated noise to signal ratio of the optical channel. Answer: B QUESTION 5: How is a Thin filter fabricated? A. The glass core is doped with an Erbium in periodic segments of the fiber. B. Layers of high index and low index material are deposited on a glass substrate. C. Thin layers of silica glass are place onto wafers to produce a prism-like effect. D. Fiber is etched with an ultraviolet laser that is precisely spaced for specific wavelength filtering. Answer: B QUESTION 6: What are three factors that limit the maximum distance of an amplified optical signal without regeneration? Select three A. Fiber dispersion B. Signal attenuation C. Transmitter power D. Amplifier bandwidth E. Receiver dispersion tolerance Answer: A, B, E QUESTION 7: Exhibit 3 http://www.testkiller.com http://www.troytec.com Slide 4: 642-321 When designing a CDWM system with multiple amplified spans, a pre-amp is needed Site B to ______. Choose three. A. Offset the OADM loss at site B. B. Overcome the high multiplexer loss at Site A. C. Amplify signal levels after the high loss through Fiber Span 1. D. Adjust add channels at Site B to be at the same level as the passthrough channels. E. Ensure that the per channel power is higher than the minimum needed for the post-amp at Site B. Answer: A, B, C Note: Uncertainty. QUESTION 8: If the dispersion of a given fiber is 17ps/nmkm at 1550 nm and zero at 1310 nm, then what is the accumulated dispersion of an ITU wavelength after it travels 200 km? A. 0 ps/nm B. 200 ps/nm C. 340 ps/nm D. 3400 ps/nm E. More information is needed Answer: D QUESTION 9: The ONS 15216 is a 32-channel system. The ONS 15216 OADMs are capable of adding and dropping one, two, or four channels. How are the OADMs provisioned to add and drop specific channels? A. The ONS 15216 OADM can be provisioned to add/drop one two, or four channels via Cisco Transport Manager (CTM). B. The ONS 15216 OADM consists only of a four-channel module, and the number of ports utilized determines whether it is a one, two, or four channel OADM. C. Three separate OADM modules are available for one, two, and four channels. The wavelengths to be dropped and added are programmable via Cisco Transport Manager (CTM). D. The ONS 15216 OADM consists only of a four-channel modul. Two-channel and four-channel support is available by stacking the single-channel module. E. The ONS 15216 OADM is available in one, two, four channels. There are 32 single-channel OADM modules, 16 two-channel OADM modules, and 8 four-channel OADM modules. Answer: E 4 http://www.testkiller.com http://www.troytec.com Slide 5: 642-321 QUESTION 10: Exhibit The exhibit shows a 15454/15216 DWDM system and alarm indications. What are two possible sources of trouble shown in the system? (Choose two.) A. Fiber failure between Sites A and D. B. EDFA failure at Site A (clockwise direction) C. EDFA failure at Site C (clockwise direction) D. 15217 multiplexer at Site A (counter-clockwise direction) E. OADM pass-through (West "OUT") failure at Site (Clockwise) F. Wavelengths 1 and 3 transmitter failures at Site A (clockwise direction) Answer: B, F QUESTION 11: What are two important considerations when using 2- or 4-channel 15216 OADMs? Choose two A. All "Add" channels require uniform power levels. B. The flexibility of wavelengths per OADM is limited. C. It is easier to balance "Pass-Through" and "Add" channels. D. There is lower pass-through loss using multi-channel OADM.s E. You can extract a single channel without dropping other channels. Answer: A, E QUESTION 12: A 2.5 Gb/s (OC-48 or STM-16) optical signal with a dispersion tolerance of 1200 ps/nm goes through fiber with 18ps/nmkm of dispersion. How many 15216-DCU-350 equivalents are needed for enough compensation after traveling 100 km? A. 0 B. 1 C. 2 D. 3 E. 4 5 http://www.testkiller.com http://www.troytec.com Slide 6: 642-321 Answer: C QUESTION 13: What are three relevant design considerations when using the 15216 EDFA? Choose three A. dispersion B. Optical SNR C. Span attenuation D. Four wave mixing E. Receiver sensitivity Answer: B, C, E QUESTION 14: Network topology exhibit Give the following paramers: Transmitter output (min): -2 dBm Receiver input (min): -28 dBm 15216 Mux and Demux loss: 4.5 dB 16 channels maximum In which sites shown in the exhibit could the 15216 EDFAs be placed to minimize the number of EDFAs needed`? A. Locations Troytec B and Troytec C only B. Locations Troytec A, Troytec B ,and Troytec C only C. Locations Troytec A, Troytec B ,and Troytec D only D. Locations Troytec B, Troytec C ,and Troytec D only E. Locations Troytec A, Troytec B , Troytec C, and Troytec D Answer: A QUESTION 15: Exhibit 6 http://www.testkiller.com http://www.troytec.com Slide 7: 642-321 What is the maximum allowable loss budget between the ONS 15216 Mux (left side) composite output and the ONS Demux (right side) composite input, with the optical values given in the exhibit? (Assume the worst case loss of 4.5 dB for 15216 200 GHz Mux/Demux and ignore power penalties or extra margin.) A. 15 dB B. 17 dB C. 21 dB D. 26 dB E. 27 dB Answer: B QUESTION 16: A VC-4-4c consists of _____. A. An STM-16 B. Any four VC-4s C. Four contiguous VC-4s D. Four contiguous STM-4s E. Two groupings of four VC-4s Answer: C QUESTION 17: Which timing mode is appropriate for an SDH NE that is adjacent to an SDH NE Bits-1 timing? A. DUS B. Line timing C. Loop timing D. Internal tiing E. Through timing Answer: B 7 http://www.testkiller.com http://www.troytec.com Slide 8: 642-321 QUESTION 18: What are two major differences between MS-SPRing and SNCP? Select two A. In an MS-SPRING, all paths are protected. B. MS-SPRing is always a high-order protections. C. A low order circuit cannot be protected by an MS-SPRing. D. There is no theoretical limit in the number of nodes in an SNCP ring. Answer: A, B QUESTION 19: What protection method is used in 4F MS-SPRing networks? A. Each fiber has half of its capacity reserved for protection. B. Two fibers carry their full capacities while the other two fibers are reserved for protection. C. The signal is sent simultaneously in both directions around the ring. The receiver determines which fiber to listen to based on signal quality. D. The signal is sent simultaneously in both directions around the ring. The transmitter determines which fiber has the working bit set for the receiver to acknowledge. Answer: B QUESTION 20 8 http://www.testkiller.com http://www.troytec.com Slide 9: 642-321 Answer: 9 http://www.testkiller.com http://www.troytec.com