Stp Timer Max-Age - H3C s3600 series Command Manual

A root bridge regularly sends out configuration BPDUs to maintain the stability of existing spanning
trees. If the switch does not receive BPDU packets in a specified period, spanning trees will be
recalculated because BPDU packets time out. When a switch becomes a root bridge, it regularly sends
BPDUs at the interval specified by the hello time you have configured on it. The other none-root-bridge
switches adopt the interval specified by the hello time.
As for the configuration of the three time-related parameters (namely, the hello time, forward delay, and
max age parameters), the following formulas must be met to prevent frequent network jitter.
2 × (forward delay – 1 second) >= max age
Max age >= 2 × (hello time + 1 second)
You are recommended to specify the network diameter of the switched network and the hello time by
using the stp root primary or stp root secondary command. After that, the three proper time-related
parameters are automatically calculated by MSTP.
Related commands: stp timer forward-delay, stp timer max-age, stp bridge-diameter.
Examples
# Set the hello time to 400 centiseconds.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] stp timer hello 400

stp timer max-age

Syntax
stp timer max-age centi-seconds
undo stp timer max-age
View
System view
Parameters
centi-seconds: Max age to be set, in the range of 600 to 4,000 (in centiseconds).
Description
Use the stp timer max-age command to set the max age of the switch.
Use the undo stp timer max-age command to restore the default max age.
By default, the max age of a switch is 2,000 centiseconds.
MSTP is capable of detecting link failures and automatically restoring redundant links to the forwarding
state. In CIST, switches use the max age parameter to judge whether or not a received configuration
BPDU times out. Spanning trees will be recalculated if a configuration BPDU received by a port times
out.
The max age is meaningless to MSTIs. The max age configured for the root bridge of the CIST applies
to all switches operating on the CIST, including the root bridge.
As for the configuration of the three time-related parameters (namely, the hello time, forward delay, and
max age parameters), the following formulas must be met to prevent frequent network jitter:
1-48