The VPN Module for the Cisco 1700 series routers optimizes the platform for virtual private networks (VPNs). The VPN module, which fits in a slot inside the Cisco 1720 or 1750 chassis, encrypts data using the Data Encryption Standard (DES) and 3DES algorithms at speeds suitable for a full-duplex T1/E1 serial connection (4 megabits per second [Mbps] for 1514-byte packets). The module, together with the platform, supports as many as 100 encrypted tunnels (400 security associations) for concurrent sessions with mobile users or other sites.