ZyXEL Communications P-793H v3 User Manual page 129

Chapter 13 VPN
Figure 75 VPN: IKE SA and IPSec SA
B
A
IPSec SA
Internet
Y
X
IKE 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 P-79X. The P-79X 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 P-79X uses the current P-79X 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).
If the remote secure gateway has a static WAN IP address, enter it in the Secure Gateway
Address field. You may alternatively enter the remote secure gateway's domain name (if it has
one) in the Secure Gateway Address field.
You can also enter a remote secure gateway's domain name in the Secure Gateway Address field
if the remote secure gateway has a dynamic WAN IP address and is using DDNS. The P-79X has to
rebuild the VPN tunnel each time the remote secure gateway's WAN IP address changes (there may
be a delay until the DDNS servers are updated with the remote gateway's new WAN IP address).
Dynamic Secure Gateway Address
If the remote secure gateway has a dynamic WAN IP address and does not use DDNS, enter 0.0.0.0
as the secure gateway's address. In this case only the remote secure gateway can initiate SAs. This
may be useful for telecommuters initiating a VPN tunnel to the company network (see Section
13.6.12 on page 147 for configuration examples).
The Secure Gateway IP Address may be configured as 0.0.0.0 only when using IKE key
management and not Manual key management.
P-79X Series User's Guide
129