3Com WX3000 operation manual Configuring the Maximum Hop Count of an MST Region, Stp max-hops hops

Configuration example

# Specify the MSTP operation mode as STP-compatible.

<device> system-view

[device] stp mode stp

Configuring the Maximum Hop Count of an MST Region

The maximum hop count configured on the region root is also the maximum hops of the MST region. The value of the maximum hop count limits the size of the MST region.

A configuration BPDU contains a field that maintains the remaining hops of the configuration BPDU. And the device discards the configuration BPDUs whose remaining hops are 0. After a configuration BPDU reaches a root bridge of a spanning tree in an MST region, the value of the remaining hops field in the configuration BPDU is decreased by 1 every time the configuration BPDU passes one device. Such a mechanism disables the devices that are beyond the maximum hop count from participating in spanning tree calculation, and thus limits the size of an MST region.

With such a mechanism, the maximum hop count configured on the device operating as the root bridge of the CIST or an MSTI in an MST region becomes the network diameter of the spanning tree, which limits the size of the spanning tree in the current MST region. The devices that are not root bridges in the MST region adopt the maximum hop settings of their root bridges.

Configuration procedure

Follow these steps to configure the maximum hop count for an MST region:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Configure the maximum hop		Required
	stp max-hops hops	By default, the maximum hop
count of the MST region
		count of an MST region is 20.

The bigger the maximum hop count, the larger the MST region is. Note that only the maximum hop settings on the device operating as a region root can limit the size of the MST region.

Configuration example

# Configure the maximum hop count of the MST region to be 30.

<device> system-view

[device] stp max-hops 30

Configuring the Network Diameter of the Switched Network

In a switched network, any two devices can communicate with each other through a specific path made up of multiple devices. The network diameter of a network is measured by the number of devices; it equals the number of the devices on the longest path (that is, the path containing the maximum number of devices).

Configuration procedure

Follow these steps to configure the network diameter of the switched network:

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