ZyXEL ISG50-PSTN User Guide - Page 96

Chapter 6 Configuration Basics 2 Policy Routes: These are the user-configured policy routes. Configure policy routes to send packets through the appropriate interface or VPN tunnel. See Chapter 14 on page 289 for more on policy routes. 3 1 to 1 and Many 1 to 1 NAT: These are the 1 to 1 NAT and many 1 to 1 NAT rules. If a private network server will initiate sessions to the outside clients, create a 1 to 1 NAT entry to have the ISG50 translate the source IP address of the server's outgoing traffic to the same public IP address that the outside clients use to access the server. A many 1 to 1 NAT entry works like multiple 1 to 1 NAT rules. It maps a range of private network servers that will initiate sessions to the outside clients to a range of public IP addresses. See Section 18.2.1 on page 325 for more. 4 Auto VPN Policy: The ISG50 automatically creates these routing entries for the VPN rules. Disabling the IPSec VPN feature's Use Policy Route to control dynamic IPSec rules option moves the routes for dynamic IPSec rules up above the policy routes (see Section 24.2 on page 370). 5 Static and Dynamic Routes: This section contains the user-configured static routes and the dynamic routing information learned from other routers through RIP and OSPF. See Chapter 14 on page 289 for more information. 6 Default WAN Trunk: For any traffic coming in through an internal interface, if it does not match any of the other routing entries, the ISG50 forwards it through the default WAN trunk. See Section 13.2 on page 285 for how to select which trunk the ISG50 uses as the default. 7 Main Routing Table: The default WAN trunk is expected to be used for any traffic that did not match any earlier routing entries. 6.5.2 NAT Table Checking Flow The checking flow is from top to bottom. As soon as the packets match an entry in one of the sections, the ISG50 stops checking the packets against the NAT table and moves on to bandwidth management. Figure 70 NAT Table Checking Flow 96 ISG50 User's Guide