Huawei AR530 Series - Setting the MSTP Timeout Interval

7.6.2.2 Setting the MSTP Timeout Interval
Context
If a device does not receive any BPDUs from the upstream device within the timeout interval,
the device considers the upstream device to have failed and recalculates the spanning tree.
Sometimes, a device cannot receive the BPDU from the upstream device within the timeout
interval because the upstream device is busy. In this case, recalculating the spanning tree will
cause a waste of network resources. To avoid wasting network resources, set a long timeout
interval on a stable network.
If a switching device does not receive any BPDUs from the upstream device within the timeout
interval, spanning tree recalculation is performed. The timeout interval is calculated as follows:
Timeout interval = Hello time x 3 x Timer Factor
Procedure
Step 1 Run:
system-view
The system view is displayed.
Step 2 Run:
stp timer-factor factor
The timeout period for waiting for BPDUs from the upstream device is set.
By default, the timeout period is 9 times the Hello timer value.
----End
7.6.2.3 Setting the Values of MSTP Timers
Context
The following timers are used in spanning tree calculation:
l Forward Delay: specifies the delay before a state transition. After the topology of a ring
network changes, it takes some time to spread the new configuration BPDU throughout the
entire network. As a result, the original blocked port may be unblocked before a new port
is blocked. When this occurs, a loop exists on the network. You can set the Forward Delay
timer to prevent loops. When the topology changes, all ports will be temporarily blocked
during the Forward Delay.
l Hello Time: specifies the interval at which hello packets are sent. A switching device sends
configuration BPDUs at the specified interval to detect link failures. If the switching device
does not receive any BPDUs within an interval of Hello Time, the switching device
recalculates the spanning tree.
l Max Age: determines whether BPDUs expire. A switching device determines that a
received configuration BPDU times out when the Max Age expires.
Devices on a ring network must use the same values of Forward Delay, Hello Time, and Max
Age.
Huawei AR530&AR550 Series Industrial Switch Routers
Configuration Guide - Ethernet Switching
7 MSTP Configuration
Issue 01 (2014-11-30) Huawei Proprietary and Confidential
Copyright © Huawei Technologies Co., Ltd.
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