The port transition hold timer delays the sending of port up or down events to Layer 2 protocols and prevents port link flapping from affecting upper layer protocols or applications. After the delay expires, the event is sent to the upper layer.
While link down events are reported immediately in the Syslog, their effect on higher level protocols such as OSPF is delayed according to how the hold timer is configured. When configured, the timer affects the physical link events. However, the resulting logical link events are also delayed.
Note
All LAG member ports must have the same delayed-link-event configuration.Note
The delayed-link-event configuration is applicable only on a physical interface. It is not valid on a VLAN, VE, LAG, or loopback interfaces.Note
The port transition hold timer does not take effect when the interface is administratively shut down.