IPSec- and MPLS-based VPNs are more suitable for site-to-site connectivity; SSL-based VPNs are better suited for remote access.
The IPSec standard provides interoperability among IP VPN devices, but deploying a VPN environment made up of products from different vendors will be more difficult to manage than a homogeneous environment.
IT managers should be prepared to implement a public-key infrastructure to provide connectivity with business partners and suppliers via extranet sites.
Companies that elect to outsource all or part of their VPN infrastructure should choose a premise-based solution when critical apps will be run on the VPN.
Companies should consider migrating to an outsourced VPN service as the virtual network grows.
VPN technologies can help secure a WLAN, but its only a temporary fix until a more secure Wi-Fi standard, such as 802.11i, gets ratified by the IEEE.