3com 8807 Guia De Referência
MSTP Configuration Commands
205
The Forward Delay configured on the root bridge determines the state transition
time.
time.
The root bridge will determine the state transition time according to the
configured values, while the other switches will apply the forward delay
configured on it.
configured values, while the other switches will apply the forward delay
configured on it.
When configuring Hello time, Forward Delay and Max Age, guarantee the
following equations:
following equations:
2 x (Forward Delay - 1.0 second) >= Max Age
Max Age >= 2 x (Hello Time + 1.0 second)
Only if the above-mentioned formulas are equal can the MSTP normally operate
on the entire network. Otherwise, the network may flap frequently. You are
recommended to use the stp bridge-diameter command to specify the diameter
of the switching network, so that MSTP can automatically calculate and give the
moderate values for the time parameters.
on the entire network. Otherwise, the network may flap frequently. You are
recommended to use the stp bridge-diameter command to specify the diameter
of the switching network, so that MSTP can automatically calculate and give the
moderate values for the time parameters.
n
Hello time, Forward Delay and Max Age affect each other. Modifying any of
them will affect the value of other two parameters.
them will affect the value of other two parameters.
Related command: stp timer hello, stp timer max-age, stp bridge-diameter.
Example
# Set the Forward Delay of the device to 2000 centiseconds.
<SW8800>system-view
System View: return to User View with Ctrl+Z.
[SW8800] stp timer forward-delay 2000
stp timer hello
Syntax
stp timer hello centi-senconds
undo stp timer hello
View
System view
Parameter
centi-senconds: Specifies Hello Time value with an integer in the range of 100 to
1000 in units of centiseconds. By default, the Hello Time of the switch is 200
centiseconds.
1000 in units of centiseconds. By default, the Hello Time of the switch is 200
centiseconds.
Description
Use the stp timer hello command to configure Hello Time of the switch.
Use the undo stp timer hello command to restore the default Hello Time.
The STP defines to transmit configuration BPDU regularly at an interval specified
with Hello Time to keep the spanning tree stable. If the switch receives no BPDU
packets for a period of time, it will recalculate the spanning tree upon the BPDU
with Hello Time to keep the spanning tree stable. If the switch receives no BPDU
packets for a period of time, it will recalculate the spanning tree upon the BPDU