The one-port PA-T3 serial port adapter provides two network interfaces per VIP2 or VIP4 for Cisco 7000 series and Cisco 7500 series routers, two network interfaces per Catalyst RSM/VIP2, and one high-speed interface on the Cisco 7200 series and Cisco uBR7200 series routers. The two-port PA-2T3 serial port adapter provides four network interfaces per VIP for Cisco 7000 series and Cisco 7500 series routers, four network interfaces for the Catalyst RSM/VIP2, and two high-speed interfaces on the 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-T3 serial port adapter provides a full-duplex synchronous serial PA-T3 interface for transmitting and receiving data at rates of up to 34 megabits per second (Mbps).