OSP Network Architecture & Design Standards 4 — Questions and Answers
Question 1: In Telcordia GR-20 standards for optical fiber cables, what does the term 'proof test' refer to?
- Testing the fiber's attenuation at multiple wavelengths
- Applying a controlled tensile stress to verify fiber mechanical integrity (Correct answer)
- Measuring the fiber's numerical aperture
- Verifying the cable's crush resistance
Correct answer: Applying a controlled tensile stress to verify fiber mechanical integrity
A proof test applies a controlled tensile load to each fiber to screen out fibers with critical flaws that could cause premature failure in service.
Question 2: What is the purpose of a 'slack loop' built into a buried fiber cable route?
- To allow for future splicing, thermal expansion, and cable retrieval without re-excavation (Correct answer)
- To increase cable attenuation for testing purposes
- To provide additional fiber count at splice points
- To meet minimum bend radius requirements only at crossings
Correct answer: To allow for future splicing, thermal expansion, and cable retrieval without re-excavation
Slack loops provide extra cable length that accommodates thermal movement, allows future splicing, and enables retrieval of damaged sections without pulling new cable.
Question 3: When designing a network using ITU-T G.652 single-mode fiber, which wavelength window is specified as the primary operating window for OSP applications?
- 850 nm
- 1310 nm and 1550 nm (Correct answer)
- 1270 nm only
- 680 nm
Correct answer: 1310 nm and 1550 nm
G.652 single-mode fiber is optimized for operation at 1310 nm (zero dispersion) and 1550 nm (minimum attenuation) windows.
Question 4: What design principle does 'zoning' in OSP network architecture refer to?
- Dividing the network into geographic service areas served by a common distribution point (Correct answer)
- Assigning different transmission frequencies to different cable routes
- Establishing separate maintenance crews for urban vs. rural areas
- Grouping all fiber splices into a central location
Correct answer: Dividing the network into geographic service areas served by a common distribution point
Zoning divides the service territory into geographic areas (zones), each served by a common distribution point, improving network manageability and scalability.
Question 5: A designer specifying conduit for a new OSP installation in an area with frequent heavy vehicle traffic must meet which minimum burial depth per NESC for conduit under a road?
- 12 inches
- 18 inches
- 24 inches
- 36 inches (Correct answer)
Correct answer: 36 inches
NESC requires a minimum burial depth of 36 inches for conduit installed under roadways subject to heavy vehicle traffic.
Question 6: In OSP aerial network design, what is the primary function of a 'messenger wire' in a lashed cable installation?
- To carry electrical power for active equipment
- To provide the structural support that bears the mechanical load of the cable (Correct answer)
- To act as a bonding conductor for lightning protection
- To guide the cable during initial installation through innerduct
Correct answer: To provide the structural support that bears the mechanical load of the cable
The messenger wire is a high-strength steel strand that provides the structural support, allowing the lashed communication cable to span between poles without bearing its own weight.
Question 7: Which OSP design document defines the specific fiber assignments (which fiber is used for which circuit) across a cable sheath?
- Route map
- Fiber assignment record or fiber assignment chart (Correct answer)
- Bill of materials
- As-built drawing showing conduit depth
Correct answer: Fiber assignment record or fiber assignment chart
A fiber assignment record (or chart) documents which specific fibers within a cable are assigned to particular circuits, splices, or customers.
OSP Network Architecture & Design Standards 4
In Telcordia GR-20 standards for optical fiber cables, what does the term 'proof test' refer to?