The Cisco 100GBASE CFP modules offer customers 100 Gigabit Ethernet connectivity options for data center networking, enterprise core aggregation, and service provider transport applications. The Cisco 100GBASE-ER4 CFP module can support link lengths up to 40 kilometers on standard duplex single-mode fiber terminated with SC/PC optical connectors. 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 CFP module supports Digital Optical Monitoring of the transmit-and-receive optical signal levels.