7-19
Follow these steps to configure the maximum number of hops of an MST region:
To do...
Use the command...
Remarks
Enter system view
system-view
—
Configure the maximum hops of
the MST region
stp max-hops
hops
Required
20 by default
Configuring the Network Diameter of a Switched Network
Any two terminal devices in a switched network are connected through a specific path comprising a
certain number of network devices. The network diameter is the number of devices on the path
comprising the most devices. The network diameter is a parameter that indicates the network size. A
bigger network diameter indicates a larger network size.
Make this configuration on the root bridge only.
Follow these steps to configure the network diameter of a switched network:
To do...
Use the command...
Remarks
Enter system view
system-view
—
Configure the network diameter of
the switched network
stp bridge-diameter
diameter
Required
7 by default
z
Based on the network diameter you configured, MSTP automatically sets an optimal hello time,
forward delay, and max age for the bridge.
z
The configured network diameter is effective for the CIST only, and not for MSTIs. Each MST
region is considered as a bridge.
Configuring Timers of MSTP
MSTP involves three timers: forward delay, hello time, and max age. You can configure these three
parameters for MSTP to calculate spanning trees.
z
To prevent temporary loops on a network, MSTP sets an intermediate port state called learning
between the discarding state and the forwarding state, that is, before a port in the discarding state
can transit to the forwarding state, it needs to go through the learning state. Forward delay is the
delay time for port state transition. This is to ensure that the state transition of the local port and that
of the peer occur in a synchronized manner.
z
Hello time is the interval at which a bridge sends configuration BPDUs to the surrounding bridges to
ensure that the paths are fault-free. If a bridge fails to receive configuration BPDUs within a certain
period of time, it starts a new spanning tree calculation process.
