Connect 400G QSFP-DD equipment interfaces across a 15 m fiber run with an active optical cable assembly rather than separate optics and patch cabling. The integrated cable construction provides a fixed-length interconnect for high-bandwidth links between compatible ports. QDD-400-AOC15M-AO is specified as Cisco-compatible, supporting installations built around Cisco QSFP-DD interface equipment. The 15 m reach suits links that extend beyond adjacent equipment while remaining within the same equipment row, cabinet group, or data center zone. Active optical cabling is suited to dense 400G connections where fiber-based transport is required between two QSFP-DD endpoints. Both cable ends are terminated for direct connection to QSFP-DD ports, so the assembly is selected by interface type, required reach, and host-platform compatibility. This specific assembly combines a 400G QSFP-DD interface format with a fixed 15 m active optical length and TAA-compliant designation. Those details matter when matching a cable to an established Cisco-compatible port environment and to sourcing requirements. Select it where the endpoints require a 400G QSFP-DD active optical interconnect and the cable path calls for 15 m of reach; it is a cable assembly, not a pluggable standalone optical module.