QDD-400-CU2.5M=

The QDD-400-CU2.5M is a passive copper cable for 400 Gigabit Ethernet, 2.5 m long, with a QSFP-DD connector fixed to each end. Label both ends at installation, since cables of different lengths look identical in a dense rack. Store unused lengths coiled loosely in their bag so the jacket and strain reliefs keep their shape. As a pre-terminated unit, it removes the need to match, stock or clean separate pluggable modules at either end. Cisco's 400G QSFP-DD data sheet lists it in the QDD-400-CU family, with forward error correction performed by the host platform. The rate is fixed by the cable type, so the port at each end must be set for the matching speed. The data sheet gives a maximum power of 1.5 W per end and a 0 to 70 degrees Celsius operating range for the copper cables. Copper at this speed is practical only over short spans, such as switch-to-server or neighbouring devices in a row. This length covers links within one rack, and reaches the next cabinet when the two racks stand side by side.