Table of Contents
Advertisement
Syntax
dampening [ half-life reuse suppress max-suppress-time ]
undo dampening
Default
Interface dampening is disabled on Ethernet interfaces.
Views
Layer 3 Ethernet interface view
Predefined user roles
network-admin
Parameters
half-life: Specifies the amount of time (in seconds) after which a penalty is decreased. The interface has
an initial penalty of 0. When the interface flaps, the penalty increases by 1000 for each down event until
the maximum penalty is reached. When the interface stops flapping, the penalty decreases by half each
time the half-life timer expires until the penalty drops to the reuse threshold. The value range for the
half-life timer is 1 to 120 seconds, and the default is 54 seconds.
reuse: Specifies the reuse threshold. When the accumulated penalty decreases to this threshold, the
interface is not dampened. Interface state changes are reported to the higher layers. The value range for
the reuse threshold is 200 to 20000, and the default is 750. The reuse threshold must be less than the
suppression threshold.
suppress: Specifies the suppression threshold. This threshold is the accumulated penalty that triggers the
device to dampen the interface. In dampened state, the interface does not report its state changes to the
higher layers. The value range for the suppression threshold is 200 to 20000, and the default is 2000.
max-suppress-time: Specifies the maximum amount of time the interface can be dampened. If the penalty
is still higher than the reuse threshold when this timer expires, the penalty stops increasing for down
events. The penalty starts to decrease until it drops below the reuse threshold. The value range for the
maximum suppression interval is 1 to 255 seconds, and the default is 162 seconds (three times the
half-life timer).
NOTE:
The maximum penalty is equal to 2
•
The penalty does not increase for up events.
•
Usage guidelines
The interface dampening feature uses an exponential decay mechanism to prevent excessive interface
flapping events from adversely affecting routing protocols and routing tables in the network.
If an interface is not dampened, its state changes are reported. For each state change, the system also
generates an SNMP notification and log message.
After a flapping interface is dampened, it does not report its state changes to the CPU. For state change
events, the interface only generates SNMP notifications and log messages. Suppression of interface state
change events protects the system processing resources.
This command does not take effect on the administratively down events. When you execute the shutdown
command, the penalty restores to 0, and the interface reports the down event to the higher layer
protocols.
(Max-suppress-time/half-life)
× reuse threshold. It is not user configurable.
6
Advertisement
Table of Contents
