3Com 4210 PWR Configuration Manual page 163

Configuring the
Network Diameter of
the Switched Network
Configuring the MSTP
Time-related Parameters
In a switched network, any two switches can communicate with each other
through a specific path made up of multiple switches. The network diameter of a
network is measured by the number of switches; it equals the number of the
switches on the longest path (that is, the path containing the maximum number
of switches).
Configuration procedure
Table 110 Configure the network diameter of the switched network
Operation
Enter system view
Configure the network
diameter of the switched
network
The network diameter parameter indicates the size of a network. The bigger the
network diameter is, the larger the network size is.
After you configure the network diameter of a switched network, an
MSTP-enabled switch adjusts its hello time, forward delay, and max age settings
accordingly to better values.
The network diameter setting only applies to CIST; it is invalid for MSTIs.
Configuration example
# Configure the network diameter of the switched network to 6.
<4210> system-view
[4210] stp bridge-diameter 6
Three MSTP time-related parameters exist: forward delay, hello time, and max age.
You can configure the three parameters to control the process of spanning tree
calculation.
Configuration procedure
Table 111 Configure MSTP time-related parameters
Operation
Enter system view
Configure the forward delay
parameter
Configure the hello time
parameter
Configure the max age
parameter
Command
system-view
stp bridge-diameter
bridgenumber
Command
system-view
stp timer forward-delay
centiseconds
stp timer hello centiseconds Required
stp timer max-age
centiseconds
Configuring Root Bridge
Description
-
Required
The default network diameter
of a network is 7.
Description
-
Required
The forward delay parameter
defaults to 1,500
centiseconds (namely, 15
seconds).
The hello time parameter
defaults to 200 centiseconds
(namely, 2 seconds).
Required
The max age parameter
defaults to 2,000
centiseconds (namely, 20
seconds).
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