Configure and Monitor IP Event Dampening

Articles » Increase the Stability of your Network » Configure and Monitor IP Event Dampening

The IP Event Dampening is configured with a single interface-level configuration command dampening [ half-time reuse-threshold suppress-threshold max-suppress-time [ restart penalty ] ] (the default values assumed by Cisco IOS are summarized in the next table). You can change as many parameters as you wish; if you specify a different half-time period and don’t specify the maximum suppress time, it’s four times the half-time period.

Parameter Default value
half time 5 seconds
reuse threshold 1000
suppress threshold 2000
maximum suppress time 20 seconds

The dampening command can be applied only on physical interfaces; IP event dampening does not work on subinterfaces or virtual templates. The events triggering the dampening penalty include a change in the interface state (loss of carrier) and the line protocol state.

There are two confusingly similar commands that monitor the IP event dampening feature: the show dampening interface displays an overview of the IP event dampening configuration and the show interface dampening displays the actual status of every interface where the IP event dampening is configured.

Display a summary of the IP event-dampening configuration
router#show dampening interface
2 interfaces are configured with dampening.
1 interface is being suppressed.
Features that are using interface dampening:
  IP Routing
  HSRP
Per-interface status of the IP event dampening
router#show interfaces dampening
Serial0/0/0
  Flaps Penalty  Supp ReuseTm HalfL ReuseV SuppV MaxSTm MaxP Restart
      0       0 FALSE       0    20   1000  2000   80  16000       0
Serial0/1/0
  Flaps Penalty  Supp ReuseTm HalfL ReuseV SuppV MaxSTm MaxP Restart
      0    2245  TRUE      33    15    500  2000   60   8000     500

The IP Event Dampening feature generates no logging messages; the only means to detect when an interface has been suppressed and later unsuppressed is through the debug dampening interface command.

You cannot use the event tracking feature of Cisco IOS, as the track interface ip routing command does not consider the dampening status of the interface and reports it as up even when it’s dampened.

Continue

Next: Dampen Other Instabilities

Sidebar