Command Manual – MSTP
H3C S7500E Series Ethernet Switches Chapter 1 MSTP Configuration Commands
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[Sysname] stp timer forward-delay 2000
1.1.38 stp timer hello
Syntax
stp timer hello centi-seconds
undo stp timer hello
View
System view
Parameters
centi-seconds: Hello time (in centiseconds), in the range of 100 to 1,000.
Description
Use the stp timer hello command to set the hello time of the device.
Use the undo stp timer hello command to restore the system default.
By default, the hello time is set to 200 centiseconds.
Hello time is the time interval at which MSTP-compliant devices send configuration
BPDUs to maintain spanning tree stability. If a device fails to receive configuration
BPDUs within the set period of time, a new spanning tree calculation process will be
triggered due to timeout. The root bridge sends configuration BPDUs at the interval of
the hello time set on the device, while secondary root bridges use the hello time set on
the root bridge.
The setting of the hello time, forward delay and max age timers must meet the following
formulae:
z 2 × (forward delay – 1 second) ú max age
z Max age ú 2 × (hello time + 1 second)
MSTP can work effectively on the entire network only when the above-mentioned
conditions are met; otherwise, network instability will frequently occur. We recommend
that you specify the network diameter of the switched network in the stp root primary
command and let MSTP automatically calculate an optimal setting of these three
timers.
Related commands: stp timer forward-delay, stp timer max-age, stp
bridge-diameter.
Examples
# Set the hello time of the device to 400 centiseconds.
<Sysname> system-view
[Sysname] stp timer hello 400
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