The Cisco 1-port OC-48c/STM-16 Packet over SONET (POS) enhanced optical services modules (OSMs) deliver advanced IP and Multiprotocol Label Switching (MPLS) services based on the Cisco Parallel Express Forwarding (PXF) network processor. The 1-port OC-48c POS includes two PXF processors - one for transmit processes and the other for receive processes.