VPN Topologies
Site-to-site VPNs

A Virtual Private Network (VPN) provides the same network connectivity for remote users over a public infrastructure as they would have over a private network. VPN services for network connectivity include authentication, data integrity, and confidentiality. There are two basic VPN types:

  • LAN-to-LAN VPNs – There are two common types of LAN-to-LAN VPNs, also known as site-to-site VPNs:
    • Intranet VPNs connect corporate headquarters, remote offices, and branch offices over a public infrastructure.
    • Extranet VPNs link customers, suppliers, partners, or communities of interest to a corporate Intranet over a public infrastructure.
  • Remote Access VPNs – Which securely connect remote users, such as mobile users and telecommuters, to the enterprise.

Site-to-site VPNs
Site-to-site VPNs can be used to connect corporate sites. In the past, a leased line or Frame Relay connection was required to connect sites. Currently, most corporations have Internet access. With Internet access, expensive leased lines and Frame Relay lines can be replaced with site-to-site VPNs. Site-to-site VPNs can be used to provide the network connection. VPNs can support company intranets and business partner extranets. Site-to-site VPN is an extension of a classic WAN network. Site-to-site VPNs can be built using routers, Security Appliances, or VPN concentrators .