Interface state changes occur when interfaces are administratively brought up or down or if an interface
state changes. Every time an interface changes state or flaps, routing protocols are notified of the status of
the routes that are affected by the change in state, and these protocols go through momentous task of
re-converging. Flapping therefore puts the status of entire network at risk of transient loops and black
Link dampening minimizes the risk created by flapping by imposing a penalty for each interface flap and
decaying the penalty exponentially. Once the penalty exceeds certain threshold, the interface is put in an
"error-disabled" state, and for all practical purposes of routing, the interface is deemed to be "down." Once
the interface becomes stable and the penalty decays below a certain threshold, the interface comes up again
and the routing protocols re-converge.
reduces processing on the CPUs by reducing excessive interface flapping.
improves network stability by penalizing misbehaving interfaces and redirecting traffic
improves convergence times and stability throughout the network by isolating failures so that
disturbances are not propagated.
Important Points to Remember
Link dampening is not supported on VLAN interfaces
Link dampening is disabled when the interface is configured for port monitoring
Link dampening can be applied to Layer 2 and Layer 3 interfaces.
Link dampening can be configured on individual interfaces in a LAG.
Enable Link Dampening
Enable link dampening using the command
interface GigabitEthernet 1/1
ip address 10.10.19.1/24
dampening 1 2 3 4
from INTERFACE mode, as shown in the following
Interfaces | 503