OSP Network Architecture & Design Standards 3 — Questions and Answers
Question 1: When designing a buried OSP network in an area with expansive clay soils, what additional design consideration is most critical?
- Increased conduit wall thickness
- Accounting for soil heave and freeze-thaw movement in burial depth and conduit selection (Correct answer)
- Using only direct-buried cable without conduit
- Reducing the number of splices
Correct answer: Accounting for soil heave and freeze-thaw movement in burial depth and conduit selection
Expansive clay soils undergo significant volume changes with moisture and temperature, which can damage conduits and cables if not accounted for in the design.
Question 2: What does the term 'feeder cable' refer to in a hierarchical OSP network design?
- Cable connecting distribution nodes to individual customers
- High-count cable running from the central office to distribution points (Correct answer)
- Drop cable from pedestal to premises
- Jumper cable used inside a splice enclosure
Correct answer: High-count cable running from the central office to distribution points
Feeder cable is the high-fiber-count backbone cable that runs from the central office or hub to distribution points serving multiple areas.
Question 3: According to NESC standards, what is the minimum vertical clearance requirement for aerial communication cables over roadways accessible to truck traffic?
- 14 feet
- 15.5 feet
- 18 feet (Correct answer)
- 22 feet
Correct answer: 18 feet
NESC requires a minimum vertical clearance of 18 feet for communication cables over roadways accessible to truck traffic.
Question 4: In an OSP design, what is the function of a serving area interface (SAI)?
- It terminates feeder cables and connects them to distribution cables for individual serving areas (Correct answer)
- It amplifies signals for long-haul transmission
- It provides power to active network elements
- It monitors fiber continuity in real time
Correct answer: It terminates feeder cables and connects them to distribution cables for individual serving areas
A SAI (also called a cross-connect box) terminates feeder cables and connects them to distribution cables, allowing flexible assignment of subscribers.
Question 5: A designer is calculating optical loss budget for a GPON distribution network. Which factor is NOT typically included in the loss budget calculation?
- Connector insertion loss
- Splice loss
- Cable attenuation per km
- Fiber chromatic dispersion (Correct answer)
Correct answer: Fiber chromatic dispersion
Chromatic dispersion affects signal quality and bandwidth but is not a power loss component included in the optical power loss budget calculation.
Question 6: What is the standard industry practice for spare fiber allocation in a new OSP fiber cable installation?
- No spare fibers are needed if the initial design is correct
- Install exactly the number of fibers needed for current demand
- Install 50–100% more fiber capacity than immediately needed (Correct answer)
- Reserve spare fibers only for government-mandated emergency services
Correct answer: Install 50–100% more fiber capacity than immediately needed
Industry practice recommends installing 50–100% additional fiber capacity beyond current needs to accommodate future growth without costly re-excavation.
Question 7: Which cable jacket type is rated for direct burial and provides rodent resistance due to its construction?
- Polyethylene (PE) jacket only
- Armored cable with steel tape or wire armor under the jacket (Correct answer)
- PVC riser-rated jacket
- Plenum-rated LSZH jacket
Correct answer: Armored cable with steel tape or wire armor under the jacket
Armored cables incorporate steel tape or wire armor beneath the outer jacket, providing mechanical protection against rodent gnawing and soil pressures.
OSP Network Architecture & Design Standards 3
When designing a buried OSP network in an area with expansive clay soils, what additional design consideration is most critical?