New topicLink-Flap Detection Threshold Value Dependencies

Dependency on Hardware Link Scan Interval

The maximum value configurable for threshold depends on the link-flap interval value and the link scan interval. For example, if the link scan interval is 50 ms (default link-scan interval on most platforms), maximum link down/up events detectable by the hardware is 20 per second. Thus the maximum number of link-flaps detectable per second is 10. If the link-flap interval is 20 seconds, the maximum configurable threshold value is 20 * 10 = 200.

Thus, the maximum configurable value for threshold = link-flap interval (seconds) * maximum link-flaps detectable/second.

Dependency on Debounce Timer

The debounce timer is implemented at the chip level. Since the link-flap algorithm is implemented at a higher level in the VLAN manager application, any link-flaps within the debounce timer are not reported to HAL nor the VLAN manager. For example, if the debounce timer is configured to be 400 ms, then any link-flaps within that interval are not reported to HAL and hence they are not counted.