本文评估的所有VPN产品均是软件产品,但是基于硬件实现VPN也日益普遍。Cisco和Bay Networks公司,还有其他一些生产路由器的公司现在也在它们的路由器和拨号访问产品中提供VPN功能。Cisco公司已生产采用第二层前向传输(L2F)隧道协议的产品,该隧道协议与Microsoft公司的点对点隧道协议(Point-to-Point Tunneling Protocol, All of the VPN products evaluated in this article are software products, but hardware-based VPNs are also becoming more commonplace. Cisco and Bay Networks, as well as other routers that make routers, now also provide VPN capabilities in their routers and dial-up access products. Cisco has produced products that employ Layer 2 Forwarding (L2F) tunneling, a protocol that is compatible with Microsoft’s Point-to-Point Tunneling Protocol