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

• The system must be reloaded after issuing the CLI for the change to take effect.

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
Example of the show interfaces dampening Command
Example of the show interfaces dampening summary Command
R1(conf-if-gi-1/1)#show config
!
interface GigabitEthernet 1/1
ip address 10.10.19.1/24
dampening 1 2 3 4
no shutdown
R1(conf-if-gi-1/1)#exit
To view the link dampening configuration on an interface, use the show config command. To view
dampening information on all or specific dampened interfaces, use the show interfaces dampening
command from EXEC Privilege mode.
Interfaces
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