Mst Region Maximum Hops Configuration - Huawei Quidway S3900 Series Operation Manual

Operation Manual – MSTP
Quidway S3900 Series Ethernet Switches-Release 1510
Operation
Configure the MSTP
operation mode for the
switch
II. Configuration example
# Configure the current switch to operate in the STP-compatible mode.
<Quidway> system-view
[Quidway] stp mode stp

1.2.7 MST Region Maximum Hops Configuration

The maximum hops values configured on the region roots in an MST region limit 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 a switch. Such a
mechanism disables the switches that are beyond the maximum hops from
participating in spanning tree generation, 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 IST 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 the MST region adopt the maximum hops settings
of their root bridges.
I. Configuration procedure
Table 1-9 Configure the maximum hops for an MST region
Operation
Enter system view
Configure the maximum
hops for the MST region
Note that only the maximum hops settings on the switches operating as region roots
can limit the size of the MST region.
Command
stp mode { stp | rstp |
mstp }
Command
system-view
stp max-hops hops
Huawei Technologies Proprietary
1-15
Chapter 1 MSTP Configuration
Description
Required
A MSTP-enabled switch
operates in the MSTP
mode by default.
Description
—
Required
By default, the maximum
hops of an MST region are
20.