The two-port PA-2E3 provides four network interfaces per VIP2 or VIP4 for Cisco 7000 series and Cisco 7500 series routers and the Catalyst RSM/VIP2 for Catalyst 5000 family switches, and two high-speed interfaces 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.