OSP Network Architecture & Design Standards 5 — Questions and Answers
Question 1: In a wavelength division multiplexing (WDM) OSP design, what does the term 'optical channel spacing' refer to?
- Physical distance between fiber cables in a conduit
- The frequency or wavelength interval between adjacent WDM channels (Correct answer)
- The number of fibers available per sheath
- Attenuation margin between amplifier stages
Correct answer: The frequency or wavelength interval between adjacent WDM channels
Optical channel spacing defines the frequency or wavelength separation between adjacent WDM channels, determining how many channels can be packed into the fiber's transmission band.
Question 2: When an OSP designer specifies a 'distribution cable' in a FTTP architecture, what portion of the network does it cover?
- From the OLT at the central office to the optical splitter
- From the optical splitter to the fiber distribution terminal serving a cluster of homes (Correct answer)
- From the fiber distribution terminal directly to the customer premises
- From the customer premises to the ONT inside the building
Correct answer: From the optical splitter to the fiber distribution terminal serving a cluster of homes
Distribution cable runs from the optical splitter location to a fiber distribution terminal (FDT) or pedestal that serves a neighborhood cluster.
Question 3: What is the maximum allowed individual splice loss for single-mode fiber as specified in most carrier OSP design standards?
- 0.01 dB
- 0.1 dB (Correct answer)
- 0.5 dB
- 1.0 dB
Correct answer: 0.1 dB
Most carrier OSP specifications allow a maximum individual fusion splice loss of 0.1 dB, with an average of 0.05 dB or less preferred.
Question 4: A network designer evaluating conduit fill rates is designing a new pull. Which maximum fill percentage is the standard industry guideline for conduit containing multiple cables?
- 25%
- 40%
- 53% (Correct answer)
- 75%
Correct answer: 53%
Industry guidelines (per NEC and Telcordia) specify a maximum conduit fill of 53% for three or more cables to allow pulling without excessive jamming probability.
Question 5: In OSP network design, what does 'make-ready' refer to in the context of pole attachment projects?
- Inspecting fiber for acceptance testing before service turn-up
- The work required to prepare existing poles and attachments to accommodate a new attachment safely and in compliance with regulations (Correct answer)
- Installing innerduct inside existing conduit for new cables
- Calculating the link budget before finalizing a design
Correct answer: The work required to prepare existing poles and attachments to accommodate a new attachment safely and in compliance with regulations
Make-ready encompasses all modifications to poles, existing attachments, and clearances necessary to safely add a new attacher's equipment while meeting NESC requirements.
Question 6: Which standard provides the basis for joint-use pole loading calculations used by OSP designers when adding new cable to a utility pole?
- TIA-758
- IEEE 802.3
- NESC (ANSI C2) (Correct answer)
- ASTM F1600
Correct answer: NESC (ANSI C2)
The National Electrical Safety Code (NESC, ANSI C2) provides the standards for pole loading, clearances, and safety requirements governing utility and communication attachments.
Question 7: A designer is comparing hub-and-spoke versus mesh OSP topologies for a metropolitan fiber network. What is the primary trade-off?
- Hub-and-spoke uses more fiber but provides more redundancy; mesh uses less fiber with single points of failure
- Hub-and-spoke is simpler with a single point of failure at the hub; mesh uses more fiber but provides multiple redundant paths (Correct answer)
- Mesh topology always requires active electronics; hub-and-spoke can be fully passive
- Hub-and-spoke requires more splice points than mesh topology
Correct answer: Hub-and-spoke is simpler with a single point of failure at the hub; mesh uses more fiber but provides multiple redundant paths
Hub-and-spoke simplifies design and management but creates a single-point-of-failure at the hub; mesh topology uses more fiber to provide multiple redundant paths between nodes.
OSP Network Architecture & Design Standards 5
In a wavelength division multiplexing (WDM) OSP design, what does the term 'optical channel spacing' refer to?