R3303-HP HSR6800 Routers Layer 2 - LAN Switching Configuration Guide

Configuring the maximum hops of an MST region

By setting the maximum hops of an MST region, you can restrict the region size. The maximum hops

configured on the regional root bridge will be used as the maximum hops of the MST region.

Configuration BPDUs sent by the regional root bridge always have a hop count set to the maximum value.

When a device receives this configuration BPDU, it decrements the hop count by 1 and uses the new hop

count in BPDUs that it propagates. When the hop count of a BPDU reaches 0, it is discarded by the

device that received it. This prevents devices beyond the reach of the maximum hop from participating in

spanning tree calculation, so the size of the MST region is limited.

Make this configuration on the root bridge only. All other devices in the MST region use the maximum

hop value set for the root bridge.

To configure the maximum number of hops of an MST region:

Step Command Remarks

1. Enter system view.

system-view N/A

2. Configure the maximum hops

of the MST region.

stp max-hops hops The default setting is 20.

Configuring the network diameter of a switched

network

Any two terminal devices in a switched network are connected through a specific path composed of a

series of devices. The network diameter is the number of devices on the path composed of the most

devices. The network diameter is a parameter that indicates the network size. A bigger network diameter

indicates a larger 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.

To configure the network diameter of a switched network:

Step Command Remarks

1. Enter system view.

system-view N/A

2. Configure the network

diameter of the switched

network in STP, RSTP, or

MSTP mode.

stp bridge-diameter diameter The default setting is 7.

Each MST region is considered as a device and the configured network diameter takes effect only on the

CIST (or MSTI 0), but not on other MSTIs.

Configuring spanning tree timers

The following timers are used for spanning tree calculations:

• Forward delay—The delay time for port state transition. To prevent temporary loops on a network,

the spanning tree sets an intermediate port state, the learning state, before it transits from the