sitetosite

Site-to-site networking refers to the connection of two or more distinct networks so they can operate as a single network. In a typical site-to-site configuration, each site has an edge device—such as a router or firewall—that forms a secure, encrypted tunnel with the corresponding device at the other site. The tunnel is usually carried over an untrusted network such as the Internet, while traffic within each site remains native to its local network.

Common topologies include point-to-point links, hub-and-spoke arrangements, and mesh configurations where every site can directly reach every other site. Site-to-site connections are widely used to link branch offices, data centers, or disaster-recovery sites to corporate networks, enabling seamless access to shared resources and centralized security policies.

Technologies used include IPsec virtual private networks (VPNs), GRE or other tunnel endpoints encapsulated over IPsec, and MPLS-based VPN services provided by telecommunications carriers. While IPsec is the most common over the public Internet, MPLS can provide site-to-site connectivity over a private backbone with QoS guarantees. Hybrid approaches may combine multiple technologies.

Benefits include secure, private communication between sites, scalable expansion of networks, centralized management of access controls, and cost savings compared to dedicated leased lines. Key considerations include bandwidth planning, latency, redundancy, key management, authentication, access control, and compliance with security policies. Operators typically monitor link health, tunnel status, and performance metrics to ensure reliability and uptime.