The NCS 4000 2 x 100G OTN Line Card supports any combination of 100 Gigabit Ethernet and OTU-4 interfaces using Cisco CPAK pluggable transceivers (Figure 9). The Cisco CPAK pluggable transceiver utilizes complementary metal-oxide semiconductor (CMOS) photonics technology to dramatically reduce the size and power consumption of 100 Gbps interfaces while maintaining IEEE and ITU protocol compliance. Two CPAK receptacles are hosted on the faceplate.