The Cisco QSFP-4X10G-LR-S QSFP module supports link lengths of up to 10km on G.652 single-mode fiber (SMF). It enables high-bandwidth 40G optical links over 12-fiber parallel fiber terminated with MPO/MTP multifiber female connectors. It can also be used in a 4x10G mode for interoperability with 10GBASE-LR interfaces up to 10km. The 4x10G connectivity is achieved using an external 12-fiber parallel to 2-fiber duplex breakout cable, which connects the 4x10G LR module to four 10GBASE-LR optical interfaces. Cisco's QSFP-4X10G-LR-S is optimized to guarantee interoperability over the full specification range of 10GBASE-LR in 4x10G mode. QSFP-4X10G-LR-S does not support FCoE.