ZyXEL Communications ISG50 User Manual

Chapter 6 Configuration Basics

ISG50 User’s Guide

This section highlights some terminology or organization for the ISG50.

Here is the order in which the ISG50 applies its features and checks.

Traffic in > Defragmentation > Destination NAT > Routing > Stateful Firewall > ADP > SNAT > 
Bandwidth Management > Fragmentation > Traffic Out.

Packet Flow  

The packet flow is as follows:

ISG50 Terminology 

IP alias

Virtual interface

Gateway policy

VPN gateway

Network policy (IPSec SA)

VPN connection

Source NAT (SNAT)

Policy route

Trigger port, port triggering

Policy route

Address mapping

Policy route

Address mapping (VPN)

IPSec VPN

Interface bandwidth management 
(outbound)

Interface

General bandwidth management

Policy route