H3C Technologies H3C SecPath F1000-E - Manual (Page 114)

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Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the network diameter of
the switched network.
stp bridge-diameter diameter 7 by default.
NOTE:
•
Based on the network diameter you configured, the system automatically sets an optimal hello time,
forward delay, and max age for the device.
• Each MST region is considered as a device and the configured network diameter is effective only for the
CIST (or the common root bridge), but not for MSTIs.
Configuring spanning tree timers
The following timers are used for spanning tree calculation:
• Forward delay
It is 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 transitions from the discarding state
to the forwarding state, and requires that the port transitions its state after a forward delay timer to
make sure that the state transition of the local port keeps synchronized with the peer.
• Hello time
The device detects whether a link failure has occurred with the hello time interval. The spanning
tree sends out a configuration BPDU every hello time interval. If the device receives no
configuration BPDUs within the hello time interval, it recalculates the spanning tree.
• Max age
In the CIST of an MSTP network, the device determines whether a configuration BPDU received by
a port has expires based on the max age timer. If yes, a new spanning tree calculation process
starts. The max age timer is ineffective for MSTIs.
To prevent network instability, make sure that the timer settings meet the following formulas:
{
2 × (forward delay – 1 second) ƒ max age
{
Max age ƒ 2 × (hello time + 1 second)
H3C does not recommend you to manually set the spanning tree timers. Instead, you can specify the
network diameter and let spanning tree protocols automatically calculate the timers based on the
network diameter. If the network diameter uses the default value, the timers also use their default values.
Configure the timers on the root bridge only, and the timer settings on the root bridge apply to all the
devices on the entire switched network.
To configure the spanning tree timers:
Step Command Remarks
1. Enter system view. system-view N/A
2. Configure the forward delay
timer.
stp timer forward-delay time
Optional.
1500 centiseconds by
default.