In this illustration, we see (from left to right) a computer labeled "Headquarters" connected to a router labeled "R1," a cloud representing the Internet," and a router labeled "R2" connecting to a computer labeled "Branch Office." The Headquarters computer has an IP address of 172.16.1/24 and the router includes the origin interface of the SA of 200.168.1.100. A blue arrow, labeled SA, extends horizontally rightward from R1 to R2, through the Internet. R2 includes the destination interface of the SA, 193.68.2.23, and the Branch Office computer has an IP address of 172.16.2/24.