The MGX-1OC12POS-IR is a single-port high-speed uplink (OC-12 POS) back card. This back card provides a trunk uplink that supports OC-12c/STM-4c bandwidth of 622 Mbps throughput over a standard SONET/SDH interface through use of a single-mode fiber, intermediate reach SC connector. The MGX-1OC12POS-IR is installed in the upper rear bay back slot directly behind the RPM-XF.