ZyXEL Communications ISG50 User Manual

ISG50 User’s Guide

A virtual private network (VPN) provides secure communications between sites without the expense 
of leased site-to-site lines. A secure VPN is a combination of tunneling, encryption, authentication, 
access control and auditing. It is used to transport traffic over the Internet or any insecure network 
that uses TCP/IP for communication.

Internet Protocol Security (IPSec) is a standards-based VPN that offers flexible solutions for secure 
data communications across a public network like the Internet. IPSec is built around a number of 
standardized cryptographic techniques to provide confidentiality, data integrity and authentication 
at the IP layer. The following figure is an example of an IPSec VPN tunnel.

IPSec VPN Example

The VPN tunnel connects the ISG50 and the remote (peer) IPSec router (X). These routers then 
connect the local network (A) and remote network (B).

Note: You can use a subscription to increase the number of supported IPSec VPN tunnels. 

.

• Use  the  VPN Connection screens (see 

) to specify which VPN gateway 

a VPN connection policy uses and which devices (behind the IPSec routers) can use the VPN 
tunnel and the IPSec SA settings (phase 2 settings). You can also activate / deactivate and 
connect / disconnect each VPN connection (each IPSec SA).

• Use  the  VPN Gateway screens  (see 

) to manage the ISG50’s VPN 

gateways. A VPN gateway specifies the IPSec routers at either end of a VPN tunnel and the IKE 
SA settings (phase 1 settings). You can also activate and deactivate each VPN gateway.