ZyXEL Prestige 660HW-D1 Wireless Router 91-004-593003B Manual Do Utilizador

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P-660H/HW-D Series User’s Guide
Appendix N Triangle Route
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Triangle Route
The Ideal Setup 
When the firewall is on, your ZyXEL Device acts as a secure gateway between your LAN and 
the Internet. In an ideal network topology, all incoming and outgoing network traffic passes 
through the ZyXEL Device to protect your LAN against attacks.
Figure 199   Ideal Setup
The “Triangle Route” Problem
A traffic route is a path for sending or receiving data packets between two Ethernet devices. 
Some companies have more than one route to one or more ISPs. If the alternate gateway is on 
the LAN (and it’s IP address is in the same subnet), the “triangle route” problem may occur. 
The steps below describe the “triangle route” problem. 
A computer on the LAN initiates a connection by sending out a SYN packet to a 
receiving server on the WAN.
The ZyXEL Device reroutes the SYN packet through Gateway on the LAN to the 
WAN. 
The reply from the WAN goes directly to the computer on the LAN without going 
through the ZyXEL Device. 
As a result, the ZyXEL Device resets the connection, as the connection has not been 
acknowledged.