The Cisco Frame Relay Service Module (FRSM) designed for use with the Cisco MGX 8230, the Cisco MGX 8250, and the Cisco MGX 8850 PXM-1 ATM multiservice edge concentrators, supports serial, channelized, or fractional unchannelized Frame Relay lines. The Cisco MGX-FRSM-HS2/B combines the features and functionality of the existing Cisco MGX-FRSM-HS2 and FRSM-HS1/B plus additional features.The Cisco MGX-FRSM-HS2/B is enhanced to offer high-speed serial frame service interfaces for the next generation of data networking. The serial port FRSMs offer connectivity to High-Speed Serial Interface (HSSI), V.35, and X.21 equipment, with the flexibility to operate as a physical data terminal equipment (DTE) or data communications equipment (DCE) interface.The Cisco MGX-FRSM-HS2/B supports eight ports of V.35 and X.21 frame services on a single, seven-inch function module. A new eight-port back card is required to take advantage of the increased connection and port densities of the Cisco MGX-FRSM-HS2/B. The Cisco MGX-FRSM-HS2/B provides unchannelized Frame Relay service on a maximum of 4, 000 connections, across 8 V.35 or X.21 interfaces. The maximum throughput for the card is 64 Mbps. The maximum rate on one line is 8 Mbps for each V.35 or X.21 interface.The Cisco MGX-FRSM-HS2/B supports two ports of HSSI frame services on a single, seven-inch function module. Two HSSI interfaces for full-duplex communications at up to 52 Mbps using the existing back card are supported. Each HSSI line consists of a serial connector, along with three LED indicators for line status. Using the FRSM-HS2/B, up to 48 HSSI ports can be operated simultaneously on the Cisco MGX 8800 ATM multiservice switch platform.