Dell C1048P Port Extender Networking Configuration Guide for the C9000 Series - Page 446

show config 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 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 R1(conf-if-te-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. Dell# show interfaces dampening Interface State Flaps Penalty Half-Life Te 0/0 Up 0 0 57 Te 0/1 Up 2 1 200 Te 0/2 Down 4 8 50 Reuse 502 20500 30600 Suppress 500 1500 2000 Max-Sup 20 300 120 Interfaces 446