When deploying a site-to-site VPN solution, you must consider the following planning and design issues:
Site network infrastructure
Windows Server 2008 includes support for the following site-to-site VPN protocols:
PPTP. PPTP uses PPP user authentication and MPPE encryption. When Microsoft Challenge Handshake Authentication Protocol (MS-CHAP v2) is used with strong passwords, PPTP is a secure VPN technology. For certificate-based authentication, EAP-TLS can be used with registry-based user certificates. PPTP is easily deployed and can be used across most network address translators (NATs).