Concept Guide

– number: enter the port number of the 100G port to be split. The range is from 1 to 32.
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 aps, routing protocols are notied of the status of the routes that are aected 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. Dampening limits the notication of status to the routing protocols. Link dampening minimizes the risk
created by apping by imposing a penalty (1024) for each interface ap and decaying the penalty exponentially based on the half-time.
When the accumulated penalty exceeds a certain threshold (suppress 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 (reuse threshold), the interface comes up again and the routing protocols re-converge.
You congure link dampening using the dampening [[[[half-life] [reuse-threshold]] [suppress-threshold]]
[max-suppress-time]] command on the interface.
Following is the detailed explanation of interface state change events:
• suppress-threshold— The suppress threshold is a value that triggers a apping interface to dampen. The system adds penalty
when the interface state goes up and down. When the accumulated penalty reaches the default or congured suppress threshold, the
interface state changes to Error-Disabled state. The range of suppress threshold is from 1 to 20000. The default is 2500.
• half-life— The accumulated penalty decays exponentially based on the half-life period. The accumulated penalty decreases half
after each half-life period. The range of half-life is from 1 to 30 seconds. The default is
5 seconds.
• reuse-threshold— After exponential decay, the penalty reaches the default or congured reuse threshold. The interface is
unsuppressed and the state changes to “up”. The range of reuse threshold is from 1 to 20000. The default is 750.
• max-suppress-time— The maximum amount of time during which the interface remain suppressed. The range is from 1 to 86400.
The default is
20 seconds or four times the default half-life period (5 seconds).
NOTE
:
suppress-threshold should be greater than reuse-threshold.
max-suppress-time should be at least 4 times half-life.
Link dampening:
• reduces processing on the CPUs by reducing excessive interface apping.
• improves network stability by penalizing misbehaving interfaces and redirecting trac.
• 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 congured for port monitoring.
• You can apply link dampening to Layer 2 and Layer 3 interfaces.
• You can congure link dampening on individual interfaces in a LAG.
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Interfaces