Nat Table Checking Flow - ZyXEL Communications ZYWALL USG 20 Manual

Chapter 6 Configuration Basics
Auto VPN Policy: The ZyWALL automatically creates these routing entries for the
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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
Static and Dynamic Routes: This section contains the user-configured static
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routes and the dynamic routing information learned from other routers through
RIP and OSPF. See
Default WAN Trunk: For any traffic coming in through an internal interface, if it
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does not match any of the other routing entries, the ZyWALL forwards it through
the default WAN trunk. See
trunk the ZyWALL uses as the default.
Main Routing Table: The default WAN trunk is expected to be used for an y traffic
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that did not match any earlier routing entries.

6.4.2 NAT Table Checking Flow

The checking flow is from top to bott om. As soon as the packets match an entry in
one of the sections, the ZyWALL stops checking the packets against the NAT table
and moves on to bandwidth management.
Figure 53 NAT Table Checking Flow
SNAT defined in the policy routes.
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1 to 1 SNAT (including Many 1 to 1) is also included in the NAT table.
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NAT loopback is now included in the NAT table instead of requiring a separate
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policy route.
94
Section 23.2 on page
Chapter 13 on page 297
Section 12.2 on page 292
394).
for more information.
for how to select which
ZyWALL USG 20/20W User's Guide