Users Guide

• QSFP port 12 in 40 G mode is plugged in with QSFP optical cables.
For these configurations, the following examples show the command output that the show interfaces tengigbitethernet
transceiver, show interfaces tengigbitethernet, and show inventory media commands displays:
NOTE: In the following show interfaces tengigbitethernet commands, the ports 1,2, and 3 are inactive and no
physical SFP or SFP+ connection actually exists on these ports. However, Dell Networking OS still perceives these ports
as valid and the output shows that pluggable media (optical cables) is inserted into these ports. This is a software
limitation for this release.
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
To view the link dampening configuration on an interface, use the show config 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
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
Gi 1/2Up005750250020
Gi 1/2Up21200205001500300
Gi 1/3Down4850306002000120
302
Interfaces