Link Dampening; Important Points To Remember; Enabling Link Dampening - Dell Force10 Z9000 Configuration Manual

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Link Dampening

Interface 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 the
change in state. These protocols go through the momentous task of re-converging. Flapping; therefore, puts the status of entire
network 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 penalty
exponentially. After the penalty exceeds a 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." After the interface becomes stable and the penalty decays below a
certain 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 Dampening

To enable link dampening, use the following command.
• Enable link dampening.
INTERFACE mode
dampening
Examples of the show interfaces dampening Commands
To view the link dampening configuration on an interface, use the show config command.
R1(conf-if-te-1/1)#show config
!
interface TenGigabitEthernet 1/1
ip address 10.10.19.1/24
dampening 1 2 3 4
no shutdown
To view dampening information on all or specific dampened interfaces, use the show interfaces dampening command from
EXEC Privilege mode.
Dell# show interfaces dampening
InterfaceStateFlapsPenaltyHalf-LifeReuseSuppressMax-Sup
Te 1/1Up005750250020
SFP 10GBASE-SX
SFP 10GBASE-SX
SFP 10GBASE-SX
SFP 10GBASE-SX
QSFP 4x10GBASE-CR1-3M
QSFP 4x10GBASE-CR1-3M
QSFP 4x10GBASE-CR1-3M
QSFP 4x10GBASE-CR1-3M
QSFP 40GBASE-SR4
APF12420031B3P
APF12420031B3P
APF12420031B3P
APF12420031B3P
APF12420031B3P
APF12420031B3P
APF12420031B3P
APF12420031B3P
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Interfaces