The ATM processor module for the Cisco 4500, Cisco 4500-M, Cisco 4700, and 4700-M routers provides a User Network Interface (UNI) between the router and an ATM network. This interface to ATM switching fabrics enables the transmitting and receiving data at rates of up to 155 Mbps in each direction (Rx and Tx). The actual rate is determined by the physical layer interface module (PLIM) and the specific physical ATM network layer. All ATM interfaces are full-duplex.