During a campus expansion, a systems administrator must install fiber between two data-center buildings that are 25 km apart, using existing underground conduit. The link must carry 10 GbE traffic today and scale to 100 GbE in the future without having to replace the cable. Rack space is limited, so the patch panels should provide the highest possible port density. Which fiber classification and connector type should the administrator deploy?
OM4 multimode fiber terminated with 12-fiber MPO connectors
OS2 single-mode fiber terminated with duplex LC connectors
OM3 multimode fiber terminated with ST connectors
OS1 single-mode fiber terminated with SC connectors
OS2 single-mode fiber is specified for long-haul, loose-tube installations and supports very low attenuation (≈0.4 dB/km), allowing links well beyond 10 km and data rates up to 100 GbE. OS1 is also single-mode but is a tight-buffer indoor cable whose higher attenuation limits practical runs to about 10 km, so it would not meet the 25 km requirement. Multimode grades such as OM3 and OM4 are optimized for short-reach links (hundreds of meters), making them unsuitable for a 25 km backbone regardless of connector type. Among common single-mode connectors, the LC small-form-factor design uses a 1.25 mm ferrule-half the size of the SC ferrule-so LC panels can fit roughly twice as many ports per rack unit, fulfilling the port-density goal. Therefore, pairing OS2 fiber with duplex LC connectors best satisfies both the distance/bandwidth and space constraints.