Note: The v4.40 or 4.30 Service Pack 681 allows masquerading VLAN interfaces
Masquerading more than one internal network is fairly simple. You need to first make sure that all of your networks are running correctly (both internal and external). You then need to enable traffic to pass to both the other internal interfaces and to be Masqueraded to the Internet.
Next, you need to enable Masquerading on the INTERNAL interfaces.
The example uses a total of three interfaces:
Both LAN_172 and, LAN_100 will be Masqueraded out of interface eth0.
Please note that it is CORRECT to have "eth0". The reason for this is the kernel needs to know which interface is used for OUTGOING traffic. Since eth0 in the above examples is the Internet connection, it is must be listed for each internal interface.