ZyXEL Communications ZyXEL ZyWALL 5 - Manual (Page 587)

ZyWALL 5 User’s Guide
586 Appendix G Triangle Route
Figure 31 “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.
1 A computer on the LAN initiates a connection by sending a SYN packet to a receiving
server on the WAN.
2 The ZyWALL reroutes the packet to Gateway B, which is in the 192.168.2.1 to
192.168.2.24 subnet.
3 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.