3Com 5500 SI - Switch - Stackable, Configuration Manual

Page: 173 / 686

Root Bridge Configuration 173
Configuration procedure
Note that only the maximum hop count setting configured on a switch acting as the
region root limits the size of the MST region.
Configuration example
Set the maximum hop count of the MST region to 30 on the future region root.
<S5500> system-view
System View: return to User View with Ctrl+Z.
[S5500] stp max-hops 30
Configuring the
Diameter of a Switched
Network
In a switched network, any two switches can communicate with each other through
paths formed by some other switches in the network. The diameter of a network
refers to the path that contains the maximum number of switches, and is measured in
the number of the switches along the path.
Configuration procedure
Network diameter is an argument intended to indicate the size of a network. A
greater network diameter indicates a larger network.
After you configure the network diameter on a switch, MSTP will automatically adjust
the Hello time, Forward delay, and Max age settings accordingly.
The network diameter setting only applies to CISTs.
Configuration example
Configure the diameter of the switched network to 6.
<S5500> system-view
System View: return to User View with Ctrl+Z.
[S5500] stp bridge-diameter 6
Configuring MSTP Time
Parameters
In MSTP, a switch has three time parameters: Forward delay, Hello time, and Max age.
■
Forward delay: Indicates the state transition delay.
Link problems occurred in a network can cause MSTP to recalculate the spanning
trees to reflect the changes of links. As it takes some time for newly generated BPDUs
to be propagated across the network, loops may occur temporarily if the new root
ports and designated ports begin to forward packets immediately.
Table 147 Configure the maximum hop count of an MST region
Operation Command Description
Enter system view system-view —
Configure the maximum hop
count of an MST region stp max-hops hops Required
By default, the maximum hop
count of an MST region is 20.
Table 148 Configure the diameter of a network
Operation Command Description
Enter system view system-view —
Configure the diameter of a
switched network stp bridge-diameter
bridgenum
Required
The default diameter of a
switched network is 7.