The Cisco MGX-CESM-T3/E3 Circuit Emulation Service Modules (CESMs) are designed for use with the MGX 8230 and MGX 8250 multiservice gateways, the MGX 8800 series wide-area edge switch and the BPX 8680 universal service node product lines. This service module offers high-speed circuit services over an ATM backbone for the new world of data networking. Growth for clear-channel T3/E3 circuit services has outpaced all other types and speeds of leased-line offerings.The new world of networking will require support for circuit services across an IP+ATM packet-switched backbone. The CESM provides this capability using standards-based adaptation of circuit interfaces onto ATM. The MGX-CESM-T3/E3 provides one port of high-speed T3 or E3 unstructured data transfer (UDT) circuit services on a single, seven-inch function module. The CESM-T3E3 provides direct connectivity to one T3 or E3 line for full-duplex communications at the DS3 rate of 44.736 MHz or at the E3 rate of 34.368 MHz. Each T3 or E3 line consists of a pair of 75-ohm BNC coaxial connectors, one for transmit data and one for receive data, along with three LED indicators for line status.