Westermo PMI-110-F2G - Manual (Page 70)

Bridge Configuration
Bridge Address: This shows the switch’s MAC address.
Priority (0‐61440): RSTP uses bridge ID to determine the root bridge, the bridge
with the highest bridge ID becomes the root bridge. The bridge ID is composed of
bridge priority and bridge MAC address. So that the bridge with the highest
priority becomes the highest bridge ID. If all the bridge ID has the same priority,
the bridge with the lowest MAC address will then become the root bridge.
Note: The bridge priority value must be in multiples of 4096. A device with a
lower number has a higher bridge priority. Ex: 4096 is higher than 32768.
Note: The Web GUI allows user select the priority number directly. This is the
convinent of the GUI design. When you configure the value through the CLI or
SNMP, you may need to type the value directly. Please follow the n x 4096 ruls
for the Bridge Priority.
Max Age (6‐40): Enter a value from 6 to 40 seconds here. This value represents
the time that a bridge will wait without receiving Spanning Tree Protocol
configuration messages before attempting to reconfigure.
If PMI is not the root bridge, and if it has not received a hello message from the
root bridge in an amount of time equal to Max Age, then PMI will reconfigure
itself as a root bridge. Once two or more devices on the network are recognized
as a root bridge, the devices will renegotiate to set up a new spanning tree
topology.
Hello Time (1‐10): Enter a value from 1 to 10 seconds here. This is a periodic
timer that drives the switch to send out BPDU (Bridge Protocol Data Unit) packet
to check current STP status.
The root bridge of the spanning tree topology periodically sends out a “hello”
message to other devices on the network to check if the topology is “healthy”.
The “hello time” is the amount of time the root has waited during sending hello
messages.
Forward Delay Time (4‐30): Enter a value between 4 and 30 seconds. This value
is the time that a port waits before changing from Spanning Tree Protocol
learning and listening states to forwarding state.
This is the amount of time PMI will wait before checking to see if it should be
changed to a different state.
Once you have completed your configuration, click on Apply to apply your
settings.
Note: You must observe the following rule to configure Hello Time, Forwarding
Delay, and Max Age parameters.
2 × (Forward Delay Time – 1 sec) ≥ Max Age Time ≥ 2 × (Hello Time value + 1
sec)
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