3com TR User Manual

In the Spanning Tree field, select *802.1d* to enable 
802.1d compliant Spanning Tree for the Switch 2000 
TR. The BPDU value is automatically assigned: 
80-01-43-00-00-00.

Select OK. Repeat for all ports as desired.

Spanning Tree is an algorithm designed to eliminate 
loops in networks. The algorithm detects and logically 
prohibits redundant paths by placing some bridge 
ports in the blocking state so that only one route exits 
between any two LANs and therefore any two sta-
tions. After Spanning Tree eliminates redundant 
paths, the network reconfigures and stabilizes. Any 
time the network topology changes the algorithm 
automatically re-learns the new configuration and 
adjusts the bridge ports accordingly. This guarantees 
that all stations are connected.

The following parameters are components of the 
Spanning Tree algorithm. These are set to factory 
defaults.

■

Priority—This setting influences the choice 
between the root bridge and the designated 
bridge. The bridge with the lowest priority is the 
one most likely to be used as the root bridge by 
Spanning Tree.

■

Entry Age—The period of time that must 
expire between sends before a MAC address is 
“aged out” (removed) from the switch data 
base (transparent bridging table).

■

Bridge Hello Time—The period of time between 
the generation of configuration messages by a 
root bridge is known as Hello Time. 

■

Bridge Max. Age—Maximum Age determines 
the amount of time the current Spanning Tree con-
figuration data is judged too old and discarded 
from the Switch 2000 TR’s memory. Maximum Age 
should never be reached in a properly configured 
Spanning Tree. 

■

Forward Delay—The Forward Delay value deter-
mines the amount of time the Switch 2000 TR 
spends in the “listening “and “learning” states. 
This prevents the forwarding of data packets until 
all parts of the topology have been notified of a 
change in the topology.