The Harder Side of VPNs

All the VPN products reviewed here are software-based, but hardware-based VPN solutions are also increasingly popular. Many router companies, such as Cisco and Bay Networks, are offering VPN functionality within their routers and dial-up access products. Cisco introduced Layer 2 Forwarding (L2F), a tunneling protocol similar to Microsoft's Point-to-Point Tunneling Protocol (PPTP), while Bay offers its BayStream IP Virtual Circuit technology.

With either of these product lines, users co nnect to the dial-up or LAN-based router using standard utilities, such as Windows 95 dial-up networking. All encryption functions are handled by the router, which establishes the virtual connection with the router at the destination network . Once end users have been authenticated, they may be totally unaware that they are connecting to their resources through an encrypted channel.

VPN functions, particularly encryption, tend to be computation-intensive, so another class of hardware-based VPN devices has emerged that offers faster overall encryption performance. Products such as the VSU-1000, from VPNet Technologies, connect directly to the network to provide authentication, encryption, and compression services for both client-to-LAN and LAN-to-LAN VPN sessions.

Because the encryption code is contained within hardware, these devices have the ability to manage more sessions at higher bandwidth levels than their software counterparts. Radguard's cIPro (slated to be available in October) is a second-generation VPN product that supports IPSEC standards for Layer 3 encryption. Radguard claims clPro can encrypt IP packets at bandwidth speed for as many as 1000 concurrent users.