ZyXEL Communications ZyXEL ZyWALL 5 - Manual (Page 98)

ZyWALL 5 User’s Guide
Chapter 5 Bridge Screens 97
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.
5.2.4 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.
5.3 Configuring Bridge
Select Bridge and click Apply in the MAINTENANCE Device Mode screen to have the
ZyWALL function as a bridge.
To change your ZyWALL’s bridge settings, click BRIDGE. The screen appears as shown.
Table 21 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.