ZyXEL Communications 70 Series ユーザーズマニュアル

ZyWALL 5/35/70 Series User’s Guide

Chapter 6 Bridge Screens

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This chapter describes how to configure bridge settings. This chapter is only applicable when 
the ZyWALL is in bridge mode.

The ZyWALL can act as a bridge between a switch and a wired LAN or between two routers. 

Be careful to avoid bridge loops when you enable bridging in the ZyWALL. Bridge loops 
cause broadcast traffic to circle the network endlessly, resulting in possible throughput 
degradation and disruption of communications. The following example shows the network 
topology that can lead to this problem: 

• If your ZyWALL (in bridge mode) is connected to a wired LAN while communicating 

with another bridge or a switch that is also connected to the same wired LAN as shown 
next.

Figure 42   Bridge Loop: Bridge Connected to Wired LAN

To prevent bridge loops, ensure that your ZyWALL is not set to bridge mode while connected 
to two wired segments of the same LAN or you enable RSTP in the Bridge screen.

STP detects and breaks network loops and provides backup links between switches, bridges or 
routers. It allows a bridge to interact with other STP-compliant bridges in your network to 
ensure that only one route exists between any two stations on the network.