ZyXEL Communications ZyWall ATP series User Manual page 382

Chapter 20 IPSec VPN
Figure 269 VPN: IKE SA and IPSec SA
In this example, a computer in network A is exchanging data with a computer in network B. Inside
networks A and B, the data is transmitted the same way data is normally transmitted in the networks.
Between routers X and Y, the data is protected by tunneling, encryption, authentication, and other
security features of the IPSec SA. The IPSec SA is secure because routers X and Y established the IKE SA
first.
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