When a site-to-site VPN is used, which protocol is responsible for the transport of user...

A site-to-site VPN allows offices in multiple fixed locations to establish secure connections with each other over a public network such as the Internet. A site-to-site VPN means that two sites create a VPN tunnel by encrypting and sending data between two devices. One set of rules for creating a siteto-site VPN is defined by IPsec.