ZyXEL Communications NWA1100-N User Manual
Chapter 6 Wireless Settings Screen
NWA1100-N User’s Guide
77
6.5.2.3 How STP Works
After a bridge determines the lowest cost-spanning tree with STP, it enables the root port and the
ports that are the designated ports for connected LANs, and disables all other ports that participate
in STP. Network packets are therefore only forwarded between enabled ports, eliminating any
possible network loops.
ports that are the designated ports for connected LANs, and disables all other ports that participate
in STP. Network packets are therefore only forwarded between enabled ports, eliminating any
possible network loops.
STP-aware bridges exchange Bridge Protocol Data Units (BPDUs) periodically. When the bridged
LAN topology changes, a new spanning tree is constructed.
LAN topology changes, a new spanning tree is constructed.
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.
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.
6.5.2.4 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.
allowed to go directly from blocking state to forwarding state so as to eliminate transient loops.
6.5.3 Additional Wireless Terms
Table 17
Additional Wireless Terms
Table 16
STP Port States
PORT STATES
DESCRIPTIONS
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.
learning process but not forwarded.
Forwarding
All BPDUs are received and processed. All information frames are received and
forwarded.
forwarded.
TERM
DESCRIPTION
Intra-BSS Traffic
This describes direct communication (not through the NWA) between two
wireless devices within a wireless network. You might disable this kind of
communication to enhance security within your wireless network.
wireless devices within a wireless network. You might disable this kind of
communication to enhance security within your wireless network.
RTS/CTS Threshold
In a wireless network which covers a large area, wireless devices are
sometimes not aware of each other’s presence. This may cause them to
send information to the AP at the same time and result in information
colliding and not getting through.
sometimes not aware of each other’s presence. This may cause them to
send information to the AP at the same time and result in information
colliding and not getting through.
By setting this value lower than the default value, the wireless devices must
sometimes get permission to send information to the NWA. The lower the
value, the more often the devices must get permission.
sometimes get permission to send information to the NWA. The lower the
value, the more often the devices must get permission.
If this value is greater than the fragmentation threshold value (see below),
then wireless devices never have to get permission to send information to
the NWA.
then wireless devices never have to get permission to send information to
the NWA.
Preamble
A preamble affects the timing in your wireless network. There are two
preamble modes: long and short.
preamble modes: long and short.
If a device uses a different preamble
mode than the NWA does, it cannot communicate with the NWA.