The PA-E3 is a single-width, one-port module that integrates data service unit (DSU) functionality into the Cisco router. The module provides one or two high-speed serial E3 interfaces.??The one-port PA-E3 provides two network interfaces per VIP2 for Cisco 7000 series and Cisco 7500 series routers, the Catalyst 6000 family FlexWAN module in the Catalyst 6000 family switches, and the Catalyst RSM/VIP2 for the Catalyst 5000 family switches, and one high-speed interface on the Cisco 7100 series, Cisco 7200 series, and Cisco uBR7200 series routers. Serial network interfaces reside on modular port adapters, which provide a direct connection between the high-speed bus in the router and the external networks. The PA-E3 provides a full-duplex synchronous serial E3 interface for transmitting and receiving data at rates of up to 34 megabits per second (Mbps).