0 4 SFP 10GBASE-SX APF12420031B3P0 5 SFP 10GBASE-SX APF12420031B3P0 6 SFP 10GBASE-SX APF12420031B3P0 7 SFP 10GBASE-SX APF12420031B3P0 8 QSFP 4x10GBASE-CR1-3M APF12420031B3P0 9 QSFP 4x10GBASE-CR1-3M APF12420031B3P0 10 QSFP 4x10GBASE-CR1-3M APF12420031B3P0 11 QSFP 4x10GBASE-CR1-3M APF12420031B3P0 12 QSFP 40GBASE-SR4Link DampeningInterface state changes occur when interfaces are administratively brought up or down or if an interface state changes.Every time an interface changes a state or flaps, routing protocols are notified of the status of the routes that are affected by thechange in state. These protocols go through the momentous task of re-converging. Flapping; therefore, puts the status of entirenetwork at risk of transient loops and black holes.Link dampening minimizes the risk created by flapping by imposing a penalty for each interface flap and decaying the penaltyexponentially. After the penalty exceeds a certain threshold, the interface is put in an Error-Disabled state and for all practicalpurposes of routing, the interface is deemed to be “down.” After the interface becomes stable and the penalty decays below acertain threshold, the interface comes up again and the routing protocols re-converge.Link dampening:• 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.• You can apply link dampening to Layer 2 and Layer 3 interfaces.• You can configure link dampening on individual interfaces in a LAG.Enabling Link DampeningTo enable link dampening, use the following command.• Enable link dampening.INTERFACE modedampeningExamples of the show interfaces dampening CommandsTo view the link dampening configuration on an interface, use the show config command.R1(conf-if-te-1/1)#show config!interface TenGigabitEthernet 1/1ip address 10.10.19.1/24dampening 1 2 3 4no shutdownTo view dampening information on all or specific dampened interfaces, use the show interfaces dampening command fromEXEC Privilege mode.Dell# show interfaces dampeningInterfaceStateFlapsPenaltyHalf-LifeReuseSuppressMax-SupTe 1/1Up005750250020Interfaces 303
