ZyWALL 5/35/70 Series User’s Guide

Once a stable network topology has been established, all bridges listen for Hello BPDUs (Bridge Protocol Data Units) transmitted from the root bridge. If a bridge does not get a Hello BPDU after a predefined interval (Max Age), the bridge assumes that the link to the root bridge is down. This bridge then initiates negotiations with other bridges to reconfigure the network to re-establish a valid network topology.

6.2.4 STP Port States

STP assigns five port states (see next table) to eliminate packet looping. A bridge port is not allowed to go directly from blocking state to forwarding state so as to eliminate transient loops.

Table 27 STP Port States

PORT STATE

DESCRIPTION

 

 

Disabled

STP is disabled (default).

 

 

Blocking

Only configuration and management BPDUs are received and processed.

 

 

Listening

All BPDUs are received and processed.

 

 

Learning

All BPDUs are received and processed. Information frames are submitted to the

 

learning process but not forwarded.

Forwarding

All BPDUs are received and processed. All information frames are received and

 

forwarded.

6.3 Bridge

Select Bridge and click Apply in the MAINTENANCE Device Mode screen to have the ZyWALL function as a bridge.

Click NETWORK, BRIDGE to display the screen shown next. Use this screen to configure bridge and RSTP (Rapid Spanning Tree Protocol) settings.

Chapter 6 Bridge Screens

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