Stp Max-Hops; Stp Mcheck - 3Com Switch 4500 Family Manual

# Enable the loop guard function on Ethernet 1/0/2 to Ethernet 1/0/4 in system view.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] stp interface Ethernet 1/0/2 to Ethernet 1/0/4 loop-protection

stp max-hops

Syntax
stp max-hops hops
undo stp max-hops
View
System view
Parameters
hops: Maximum hop count to be set. This argument ranges from 1 to 40.
Description
Use the stp max-hops command to set the maximum hop count for the MST region the current switch
belongs to.
Use the undo stp max-hops command to restore the maximum hop count to the default.
By default, the maximum hop count of an MST region is 20.
The maximum hop count configured on the region roots of an MST region limits the size of the MST
region.
A configuration BPDU contains a field that maintains the remaining hops of the configuration BPDU.
And a switch discards the configuration BPDUs whose remaining hops are 0. After a configuration
BPDU reaches a root bridge of a spanning tree in a MST region, the value of the remaining hops field in
the configuration BPDU is decreased by 1 every time the configuration BPDU passes one switch. Such
a mechanism disables the switches that are beyond the maximum hops from participating in spanning
tree calculation, and thus limits the size of an MST region.
With such a mechanism, the maximum hops configured on the switch operating as the root bridge of the
CIST or an MSTI in a MST region becomes the network diameter of the spanning tree, which limits the
size of the spanning tree in the current MST region. The switches that are not root bridges in an MST
region adopt the maximum hop settings of the root bridge.
Examples
# Set the maximum hop count of the current MST region to 35.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] stp max-hops 35

stp mcheck

Syntax
Ethernet port view:
1-24