N10-009 Question 93
Single answer1.5 Compare and contrast transmission media and transceivers.A company is expanding into a warehouse located 450 meters from the main office. The path between buildings runs alongside large industrial motors and fluorescent lighting, and the network team needs to provide a 10 Gbps uplink between the two building switches. The switches support modular transceivers. Which solution best meets the bandwidth requirement while minimizing the risk of electromagnetic interference?
- A
Install Cat 6a copper cabling with 10GBASE-T transceivers between the buildings
- B
Install multimode fiber with SFP+ 10GBASE-SR transceivers between the buildings
- C
Install single-mode fiber with SFP+ 10GBASE-LR transceivers between the buildings
- D
Install RG6 coaxial cabling with F-type connectors and media converters between the buildings
Show answer and explanation
Correct answer: C
Explanation
The key factors are distance, bandwidth, and interference. Twisted-pair Ethernet such as 10GBASE-T is generally limited to 100 meters, so it cannot support a 450-meter run. Fiber is preferred for inter-building links because it is not affected by electromagnetic interference and can support greater distances. Between the two fiber choices, 10GBASE-SR over multimode is typically used for shorter distances, while 10GBASE-LR over single-mode is designed for long-range links and comfortably supports 450 meters. This aligns with Ethernet physical layer standards defined by IEEE 802.3, where 10GBASE-T covers copper twisted pair, 10GBASE-SR covers short-range optical links, and 10GBASE-LR covers long-range single-mode fiber deployments. In practice, best design guidance for campus and building-to-building uplinks favors fiber, especially where EMI or lightning-related electrical isolation concerns exist.
- A. Incorrect.
Cat 6a can support 10GBASE-T up to 100 meters under standards-based conditions, but this link is 450 meters, far beyond the maximum Ethernet segment length for twisted-pair copper. Copper is also more susceptible to electromagnetic interference from industrial motors and lighting. A candidate might choose this option because Cat 6a is commonly associated with 10 Gbps Ethernet, but the distance and EMI concerns make it unsuitable.
- B. Incorrect.
10GBASE-SR over multimode fiber is resistant to electromagnetic interference and is commonly used for short-range 10 Gbps links. However, its supported distance is much shorter than 450 meters in typical enterprise deployments, depending on the multimode fiber type and modal bandwidth. This makes it an unreliable choice for a 450-meter building-to-building uplink. Someone might pick this because multimode fiber is often less expensive than single-mode and is popular inside buildings, but the distance is the limiting factor.
- C. Correct.
Single-mode fiber with 10GBASE-LR SFP+ transceivers is the best choice. Fiber is immune to electromagnetic interference, which is important in an environment with large motors and fluorescent lighting. 10GBASE-LR is designed for long-range 10 Gigabit Ethernet over single-mode fiber and easily supports a 450-meter link. This solution matches both the distance requirement and the environmental conditions while using the switches' modular transceiver capability.
- D. Incorrect.
RG6 coaxial cabling with F-type connectors is commonly used for cable television and broadband services, not as a standard medium for a 10 Gbps switched Ethernet uplink between enterprise switches. Although media converters exist for some niche applications, this is not a practical or standards-aligned solution for this scenario. A candidate might select this if they confuse broadband coax use cases with enterprise switch uplinks.