Cisco - Expansion module - expansion slot - ATM - OC-3

The ATM OC-3 Network Module is an ATM network module designed for Optical Carrier level 3 (OC3) high-bandwidth data and voice or data integration applications over Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) at speeds of 155.520 Mbps (STM-1). The ATM OC-3 network module can combine router packets with constant bit rate (CBR) data onto an ATM uplink.