Replicate data over the Internet using:
Virtual Private Network (VPN)
Virtual Private Networking (VPN) technology allows users working at home, branch offices, remote clients, and other companies to connect to a corporate network over the Internet, while maintaining secure communications. Users can use Windows Authentication as though they were on a Local Area Network (LAN). All types of Microsoft SQL Server replication can replicate data over a VPN, but consider using Web synchronization if you are using merge replication, because Web synchronization eliminates the need for a VPN.
A VPN includes client software so that computers connect over the Internet (or in special cases, even an intranet) to software in a dedicated computer or a server. Optionally, encryption at both ends, as well as user authentication methods, are used. The VPN connection over the Internet logically operates as a Wide Area Network (WAN) link between the sites.
A VPN connects the components of a network using another network. To connect, the user tunnels through the Internet or another public network using a protocol such as Microsoft Point-to-Point Tunneling Protocol (PPTP) or Layer Two Tunneling Protocol (L2TP). This process provides the same security and features previously available only in a private network. PPTP is available with the Microsoft Windows NT version 4.0 and Microsoft Windows 2000 (and later) operating systems; L2TP is available with Windows 2000 and later.
For the user, the intermediate routing infrastructure of the Internet is not visible and it appears as though the data is being sent over a dedicated private link. As far as users are concerned, the VPN is a point-to-point connection between the user computer and a corporate server.
After you have your remote client configured to connect using a VPN, and the client has Internet access and is logged in to the corporate LAN, you can configure replication as though the remote client is connected directly on the LAN. For security reasons, it is possible to have different network resources available to users connected over VPN and to those connected directly on the LAN.
The Web synchronization option for merge replication
Web synchronization for merge replication lets you replicate data by using the HTTPS protocol, and is useful for the following scenarios:
- Synchronizing data from mobile users over the Internet.
- Synchronizing data between Microsoft SQL Server databases across a corporate firewall.
For example, a traveling sales representative can use Web synchronization. The company, Adventure Works Cycles, has sales representatives that travel to various stores and suppliers throughout their regions. On longer trips the representatives stay in hotels and need a convenient way to upload sales data and download any product updates at the end of each day.
The Adventure Works IT department has configured each portable computer with SQL Server and has enabled merge replication to use Web synchronization. The Merge Agent on each portable computer has an Internet URL that points to the replication components that are installed on a computer that is running Microsoft Internet Information Services (IIS). These components synchronize the Subscriber with the Publisher. Each representative can now connect through any available Internet connection without using a remote dial-up connection, and can upload and download the appropriate data. The Internet connection uses Secure Sockets Layer (SSL); therefore, a virtual private network (VPN) is not required.