The Cisco 100GBASE-ER4 (Figure 1) CFP2 module can support link lengths up to 40 kilometers on standard duplex single-mode fiber (SMF, G.652) terminated with LC optical connectors. The 100 Gigabit Ethernet signal is carried over four wavelengths. Multiplexing and demultiplexing of the four wavelengths are managed within the device. The Cisco 100GBASE-ER4 CFP2 module meets the IEEE 802.3ba requirements for 100GBASE-ER4 performance and also supports DOM of the transmit-and-receive optical signal levels.