Why interface flapping

Enable link flapping protection on all interfaces. Enter Ethernet interface view. Enable link flapping protection on an interface. By default, link flapping protection is disabled on all interfaces.

By default, link flapping protection is disabled on an interface. Configuring dampening on an Ethernet interface. Enabling loopback testing on an Ethernet interface. Sort the results by host total and secondarily by message count, with the highest values first. The following sample result from the search shows the host, source interface, current port status, and the count for the host. The sparkline is not shown below but would be rendered by Splunk. Prerequisites In order to execute this procedure in your environment, the following data, services, or apps are required: Splunk Enterprise or Splunk Cloud Platform Cisco Networks Add-on for Splunk Enterprise Syslog data collection tier The Cisco IOS system message logging process uses the syslog protocol to send important messages to remote logging services, such as Splunk.

Example Common causes for port flapping are bad, unsupported, or non-standard cable or other link synchronization issues. To optimize the search shown below, you should specify an index and a time range. Search explanation The table provides an explanation of what each part of this search achieves. Result The following sample result from the search shows the host, source interface, current port status, and the count for the host.

Search for port up and port down events in all Cisco IOS data. By default, link flapping protection is disabled on an interface.

Optional Run: port link-flap interval interval-value The link flapping period is configured for the interface. By default, the link flapping period for an interface is 10 seconds. Optional Run: port link-flap threshold threshold-value The number of link flappings is configured for the interface. By default, the number of link flappings for an interface is 5. Checking the Configuration Run the display error-down recovery [ interface interface-type interface-number ] command in any view to check information about the interface in Error-down state.

Follow-up Procedure An interface in Error-down state can be recovered using either of the following methods: Manual recovery: If a few interfaces need to be recovered forcibly, run the shutdown and undo shutdown commands in the interface view. Alternatively, run the restart command in the interface view to restart the interfaces. Automatic recovery: If a large number of interfaces need to be recovered, manual recovery is time consuming and some interfaces may be omitted.