Owners Manual

NOTE: In the following show inventory media command output, the port numbers 1, 2, 3, 5, 6,
and 7 ports are actually inactive. However, Dell Networking OS still shows that optical cables are
inserted into these ports. This is a software limitation for this release.
Dell# show inventory media
Slot Port Type Media Serial Number
-------------------------------------------------------------------
0 0 SFP+ 10GBASE-SX APF12420031B3P
0 1 SFP+ 10GBASE-SX APF12420031B3P
0 2 SFP+ 10GBASE-SX APF12420031B3P
0 3 SFP+ 10GBASE-SX APF12420031B3P
0 4 SFP 10GBASE-SX APF12420031B3P
0 5 SFP 10GBASE-SX APF12420031B3P
0 6 SFP 10GBASE-SX APF12420031B3P
0 7 SFP 10GBASE-SX APF12420031B3P
0 8 QSFP 4x10GBASE-CR1-3M APF12420031B3P
0 9 QSFP 4x10GBASE-CR1-3M APF12420031B3P
0 10 QSFP 4x10GBASE-CR1-3M APF12420031B3P
0 11 QSFP 4x10GBASE-CR1-3M APF12420031B3P
0 12 QSFP 40GBASE-SR4
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.
438
Interfaces