3Com 7757 Configuration Manual page 252

252 C 30: MSTP C
HAPTER
Network Diameter
Configuration
MSTP Time-related
Configuration
ONFIGURATION
Configuration example
# Configure the maximum hops of the MST region to be 30 (assuming that the
current switch operates as the region root).
<SW7750> system-view
[SW7750] stp max-hops 30
In a switched network, any two switches can communicate with each other
through a path, on which there may be some other 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 contains the
maximum number of switches).
Configuration procedure
Table 178 Configure the network diameter for a network
Operation
Enter system view
Configure the
network diameter for
a network
The network diameter parameter indicates the size of a network. The larger the
network diameter is, the larger the network size is.
After you configure the network diameter of a switched network, A
MSTP-enabled switch adjusts its Hello time, Forward delay, and Max age settings
accordingly.
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.
<SW7750> system-view
[SW7750] stp bridge-diameter 6
You can configure three MSTP time-related parameters for a switch: Forward
delay, Hello time, and Max age.
The Forward delay parameter sets the delay of state transition.
■
Link problems occurred in a network results in the spanning trees being
regenerated and original spanning tree structures being changed. As the newly
generated configuration BPDUs cannot be propagated across the entire network
immediately when the new spanning trees are generated, loops may occur if the
new root ports and designated ports begin to forward packets immediately.
This can be avoided by adopting a state transition mechanism. With this
mechanism, newly selected root ports and designated ports undergo an
intermediate state before they begin to forward packets. That is, it costs these
ports a period (specified by the Forward delay parameter) for them to turn to the
forwarding state. The period ensures that the newly generated configuration
BPDUs to propagate across the entire network.
Command
system-view
stp bridge-diameter
bridgenumber
Description
-
Required
The default network diameter of a
network is 7.