Configuring The Network Diameter Of A Switched Network; Setting Spanning Tree Timers - H3C S7500X Series Configuration Manual

uses the new hop count in the BPDUs that it propagates. When the hop count of a BPDU reaches
zero, it is discarded by the device that received it. Devices beyond the reach of the maximum hops
can no longer participate in spanning tree calculations, so the size of the MST region is limited.
Make this configuration only on the root bridge. All other devices in the MST region use the maximum
hop value set for the root bridge.
You can configure the maximum hops of an MST region based on the STP network size. As a best
practice, set the maximum hops to a value that is greater than the maximum hops of each edge
device to the root bridge.
To configure the maximum number of hops of an MST region:
Step
Enter system view.
1.
Configure the maximum
2.
hops of the MST region.
Configuring the network diameter of a switched
network
Any two terminal devices in a switched network can reach each other through a specific path, and
there are a series of devices on the path. The switched network diameter is the maximum number of
devices on the path for an edge device to reach another one in the switched network through the root
bridge. The network diameter indicates the network size. The bigger the diameter, the larger the
network size.
Based on the network diameter you configured, the system automatically sets an optimal hello time,
forward delay, and max age for the device.
In STP, RSTP, or MSTP mode, each MST region is considered a device. The configured network
diameter takes effect only on the CIST (or the common root bridge) but not on other MSTIs.
In PVST mode, the configured network diameter takes effect only on the root bridges of the specified
VLANs.
To configure the network diameter of a switched network:
Step
Enter system view.
1.
Configure the network
2.
diameter of the switched
network.

Setting spanning tree timers

The following timers are used for spanning tree calculation:
•
Forward delay—Delay time for port state transition. To prevent temporary loops on a network,
the spanning tree feature sets an intermediate port state (the learning state) before it transits
from the discarding state to the forwarding state. The feature also requires that the port transit
its state after a forward delay timer. This ensures that the state transition of the local port stays
synchronized with the peer.
Command
system-view
stp max-hops hops
Command
system-view
•
In STP/RSTP/MSTP mode:
stp bridge-diameter diameter
•
In PVST mode:
stp vlan vlan-id-list bridge-diameter
diameter
29
Remarks
N/A
The default setting is 20.
Remarks
N/A
The default setting is 7.