3com S7906E Guide De Référence

 

1-35 

# Set the hello time of the device to 400 centiseconds.  

<Sysname> system-view 

[Sysname] stp timer hello 400 

stp timer max-age centi-seconds 

undo stp timer max-age 

System view 

2: System level 

centi-seconds: Max age (in centiseconds), ranging from 600 to 4000 in steps of 100. 

Use the stp timer max-age command to set the max age timer of the device.  

Use the undo stp timer max-age command to restore the system default.  

By default, the max age is set to 2,000 centiseconds.  

MSTP can detect link failures and automatically restore the forwarding state of the redundant link. In the 

CIST, the device determines whether a configuration BPDU received on a port has expired based on 

the max age timer. If a port receives a configuration BPDU that has expired, that MSTI needs to be 

re-computed.  

The max age timer is not meaningful for MSTIs. If the current device is the root bridge of the CIST, it 

determines whether a configuration BPDU has expired based on the configured max age timer; if the 

current device is not the root bridge of the CIST, it uses the max age timer set on the CIST root bridge.  

The settings 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, topology changes will frequently occur. We recommend that you specify the network 

diameter 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 hello, stp bridge-diameter.  

# Set the max age timer of the device to 1,000 centiseconds.  

<Sysname> system-view 

[Sysname] stp timer max-age 1000