ZyXEL Communications 5 Series User Manual

 Chapter 8 Bridge Screens

ZyWALL 5/35/70 Series User’s Guide

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 34   STP Port States

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.