The cisco 40gbase-sr4 qsfp modules support link lengths of 100 meters and 150 meters, respectively, on laser-optimized om3 and om4 multimode fibers. It primarily 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 breakout mode for interoperability with 10gbase-sr and sfp-10/25g-csr-s (in 10g mode) interfaces up to 100 and 150 meters on om3 and om4 fibers, respectively. The worry-free 4x10g mode operation is enabled by the optimization of the transmit and receive optical characteristics of the cisco qsfp-40g-sr4 to prevent receiver overload or unnecessary triggering of alarm thresholds on the 10gbase-sr and sfp-10/25g-csr-s (in 10g mode) receiver, and at the same time is completely interoperable with all standard 40gbase-sr4 interfaces.