ZyXEL P-2602HW Betriebsanweisung

Chapter 17 Introduction to IPSec

P-2602H(W)(L)-DxA User’s Guide

Figure 136   Encryption and Decryption

The IPSec sender can encrypt packets before transmitting them across a network. 

The IPSec receiver can validate packets sent by the IPSec sender to ensure that the data has not 
been altered during transmission. 

The IPSec receiver can verify the source of IPSec packets. This service depends on the data 
integrity service. 

The ZyXEL Device supports the following VPN applications.

• Linking Two or More Private Networks Together

Connect branch offices and business partners over the Internet with significant cost 
savings and improved performance when compared to leased lines between sites. 

• Accessing Network Resources When NAT Is Enabled

When NAT is enabled, remote users are not able to access hosts on the LAN unless the 
host is designated a public LAN server for that specific protocol. Since the VPN tunnel 
terminates inside the LAN, remote users will be able to access all computers that use 
private IP addresses on the LAN.

• Unsupported IP Applications

A VPN tunnel may be created to add support for unsupported emerging IP applications. 
See 

 for an example of a VPN application.

The overall IPSec architecture is shown as follows.