Stp Timer Forward-Delay - H3C S7500E Series Command Manual

Command Manual – MSTP
H3C S7500E Series Ethernet Switches

1.1.37 stp timer forward-delay

Syntax
stp timer forward-delay centi-seconds
undo stp timer forward-delay
View
System view
Parameters
centi-seconds: Forward delay in centiseconds, in the range of 400 to 3,000.
Description
Use the stp timer forward-delay command to set the forward delay timer of the
device.
Use the undo stp timer forward-delay command to restore the system default.
By default, the forward delay timer is set to 1,500 centiseconds.
In order to prevent temporary loops, a port must go through an intermediate state, the
learning state, before it transitions from the discarding state to the forwarding state, and
must wait a certain period of time before it transitions from one state to another to keep
synchronized with the remote device during state transition. The forward delay timer set
on the root bridge determines the time interval of state transition.
If the current device is the root bridge, the state transition interval of the device depends
on the set forward delay value; for a secondary root bridge, its state transition interval is
determined by the forward delay timer set on the root bridge.
The setting of the hello time, forward delay and max age timers must meet the following
formulae:
2 × (forward delay – 1 second) ú max age
Max age ú 2 × (hello Time + 1 second)
MSTP can work effectively on the entire network only when the above-mentioned
conditions are met; otherwise, network instability will frequently occur. We recommend
that you specify the network diameter of the switched network in the stp root primary
command and let MSTP automatically calculate an optimal setting of these three
timers.
Related commands: stp timer hello, stp timer max-age, stp bridge-diameter.
Examples
# Set the forward delay timer of the device to 2,000 centiseconds.
<Sysname> system-view
Chapter 1 MSTP Configuration Commands
1-35