What You Need To Know About Ipsec Vpn - ZyXEL Communications P-661HNU Manual

Chapter 16 VPN

16.1.2 What You Need to Know About IPSec VPN

A VPN tunnel is usually established in two phases. Each phase establishes a
security association (SA), a contract indicating what security parameters the
ZyXEL Device and the remote IPSec router will use. The first phase establishes an
Internet Key Exchange (IKE) SA between the ZyXEL Device and remote IPSec
router. The second phase uses the IKE SA to securely establish an IPSec SA
through which the ZyXEL Device and remote IPSec router can send data between
computers on the local network and remote network. The following figure
illustrates this.
Figure 95 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 established securely using the IKE SA that routers X
and Y established first.
My IP Address
My IP Address is the WAN IP address of the ZyXEL Device. The ZyXEL Device has
to rebuild the VPN tunnel if My IP Address changes after setup.
The following applies if this field is configured as 0.0.0.0:
• The ZyXEL Device uses the current ZyXEL Device WAN IP address (static or
dynamic) to set up the VPN tunnel.
Secure Gateway Address
Secure Gateway Address is the WAN IP address or domain name of the remote
IPSec router (secure gateway).
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A
X
IPSec SA
Y
IKE SA
B
P-661HNU-Fx User's Guide