System-Guard Tcn Enable; System-Guard Tcn Rate-Threshold - 3Com Switch 4500 Family Manual

system-guard tcn enable

Syntax
system-guard tcn enable
undo system-guard tcn enable
View
System view
Parameters
None
Description
Use the system-guard tcn enable command to enable System Guard against TCN attacks.
Use the undo system-guard tcn enable command to disable System Guard against TCN attacks.
With this feature enabled, System Guard monitors the TCN/TC packet receiving rate on the ports. If the
rate exceeds the preset threshold, the system will output trap and log information to notify the user and
starts to send only on TCN/TC packet to the CPU in a 10-second cycle. This can prevent MAC and ARP
entries from being frequently deleted by STP or RSTP; in addition, when the TCN/TC packet rate
exceeds the preset threshold, proper measures can be taken based on the output trap and log
information.
By default, this feature is disabled.
Examples
# Enable System Guard against TCN attacks.
<Sysname> system-view
System View: return to User View with Ctrl+Z.
[Sysname] system-guard tcn enable

system-guard tcn rate-threshold

Syntax
system-guard tcn rate-threshold rate-threshold
undo system-guard tcn rate-threshold
View
System view
Parameters
rate-threshold: TCN/TC packet receiving rate in packets per second (pps), with an effective range of 1
to 20.
Description
Use the system-guard tcn rate-threshold command to set the threshold of TCN/TC packet receiving
rate, which will trigger the output of trap and log information.
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