ZyXEL Communications 70 Series User Manual

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ZyWALL 5/35/70 Series User’s Guide
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Appendix I Triangle Route
Figure 453   “Triangle Route” Problem
The “Triangle Route” Solutions
This section presents you two solutions to the “triangle route” problem. 
IP Aliasing 
IP alias allows you to partition your network into logical sections over the same Ethernet 
interface. Your ZyWALL supports up to three logical LAN interfaces with the ZyWALL 
being the gateway for each logical network. By putting your LAN and Gateway B in different 
subnets, all returning network traffic must pass through the ZyWALL to your LAN. The 
following steps describe such a scenario.
A computer on the LAN initiates a connection by sending a SYN packet to a receiving 
server on the WAN. 
The ZyWALL reroutes the packet to Gateway B, which is in the 192.168.2.1 to 
192.168.2.24 subnet. 
The reply from WAN goes through the ZyWALL to the computer on the LAN in the 
192.168.1.1 to 192.168.1.24 subnet.