H3C Technologies H3C SecPath F1000-E - Manual (Page 115)

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Step Command Remarks
3. Configure the hello timer. stp timer hello time
Optional.
200 centiseconds by default.
4. Configure the max age timer. stp timer max-age time
Optional.
2000 centiseconds by
default.
NOTE:
•
The length of the forward delay timer is related to the network diameter of the switched network. The
larger the network diameter is, the longer the forward delay time should be. If the forward delay timer
is too short, temporary redundant paths may be introduced. If the forward delay timer is too long, it may
take a long time for the network to converge. H3C recommends you to use the default setting.
• An appropriate hello time setting enables the device to promptly detect link failures on the network
without using excessive network resources. If the hello time is too long, the device will consider packet
loss as a link failure and trigger a new spanning tree calculation process. If the hello time is too short,
the device will frequently send the same configuration BPDUs, which add the device burden and waste
network resources. H3C recommends you to use the default setting.
• If the max age timer is too short, the device will frequently launch spanning tree calculation and may
consider network congestion as a link failure. If the max age timer is too long, the device may fail to
detect link failures and launch spanning tree calculations promptly, reducing the auto-sensing capability
of the network. H3C recommends you to use the default setting.
Configuring the timeout factor
The timeout factor is a parameter used to decide the timeout time, in the following formula: Timeout time
= timeout factor × 3 × hello time.
After the network topology is stabilized, each non-root-bridge device forwards configuration BPDUs to
the downstream devices at the interval of hello time to check whether any link is faulty. If a device does
not receive a BPDU from the upstream device within nine times the hello time, it assumes that the
upstream device has failed and starts a new spanning tree calculation process.
Sometimes a device may fail to receive a BPDU from the upstream device because the upstream device
is busy. If a spanning tree calculation occurs, the calculation can fail and also waste the network
resources. In a stable network, you can prevent undesired spanning tree calculations by setting the
timeout factor to 5, 6, or 7.
To configure the timeout factor:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the timeout factor of the
device.
stp timer-factor factor 3 by default.