Site-to-Site VPN
Two gateways hold a permanent tunnel so whole networks can talk.
How widely is it used?
Among the most widely deployed options in 2026The default way to join two networks; IPsec remains the interoperable choice.
How it works
Routers or firewalls at each location negotiate a tunnel and route the other side's subnets through it. Individual hosts need no VPN software — the gateways do the work.
Connects
Network → network
Protocols
IPsec, GRE over IPsec, WireGuard
Typical users
Businesses with more than one location
Main use case
Connecting branch offices and data centres.
Advantages
- Invisible to end users
- One tunnel serves every device at the site
Limitations
- Routing and subnet planning must be right
- A broken tunnel takes the whole site offline