4-7system-guard tcn enableSyntaxsystem-guard tcn enableundo system-guard tcn enableViewSystem viewParametersNoneDescriptionUse 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 therate exceeds the preset threshold, the system will output trap and log information to notify the user andstarts to send only on TCN/TC packet to the CPU in a 10-second cycle. This can prevent MAC and ARPentries from being frequently deleted by STP or RSTP; in addition, when the TCN/TC packet rateexceeds the preset threshold, proper measures can be taken based on the output trap and loginformation.By default, this feature is disabled.Examples# Enable System Guard against TCN attacks. system-viewSystem View: return to User View with Ctrl+Z.[Sysname] system-guard tcn enablesystem-guard tcn rate-thresholdSyntaxsystem-guard tcn rate-threshold rate-thresholdundo system-guard tcn rate-thresholdViewSystem viewParametersrate-threshold: TCN/TC packet receiving rate in packets per second (pps), with an effective range of 1to 20.DescriptionUse the system-guard tcn rate-threshold command to set the threshold of TCN/TC packet receivingrate, which will trigger the output of trap and log information.
