H3C S7500 Series Ethernet Switches Command Manual

Command Manual – MSTP
H3C S7500 Series Ethernet Switches Chapter 1
MSTP Configuration Commands
1-42
Examples
# Enable the TC-BPDU guard function on the switch.
<H3C> system-view
System View: return to User View with Ctrl+Z.
[H3C] stp tc-protection enable
1.1.40 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 to be set. This argument ranges from
400 to 3,000 and defaults to 1,500.
Description
Use the stp timer forward-delay command to set the forward delay of the switch.
Use the undo stp timer forward-delay command to revert to the default Forward
delay.
To prevent the occurrence of temporary loops, when a port changes its state from
discarding to forwarding, it undergoes an intermediate state and waits for a specific
period to synchronize with the remote switches. This state transition period is
determined by the Forward delay configured on the root bridge.
The Forward delay setting configured on a root bridge applies to all switches operating
in the same MSTI.
As for the configuration of the three time-related parameters (that is, the Hello time,
Forward delay, and Max age parameters), the following formulas must be met to
prevent network jitter.
2 x (Forward delay – 1 second) >= Max age
Max age >= 2 x (Hello time + 1 second)
You are recommended to specify the network diameter of the switched network and the
Hello time by using the stp root primary or stp root secondary command. After that,
the three proper time-related parameters are automatically determined.
Related commands: stp timer hello, stp timer max-age, stp bridge-diameter.