Configuring Dampening On An Ethernet Interface - H3C SR6600 Configuration Manual

To prevent frequent physical link flapping from affecting system performance, configure physical
state change suppression. You can configure this feature to suppress only link-down events, only
link-up events, or both. If an event of the specified type still exists when the suppression interval
expires, the system reports the event.
When you configure this feature, follow these guidelines:
•
To suppress only link-down events, configure the link-delay [ msec ] delay-time command.
•
To suppress only link-up events, configure the link-delay [ msec ] delay-time mode up
command.
•
To suppress both link-down and link-up events, configure the link-delay [ msec ] delay-time
mode updown command.
To configure physical state change suppression on an Ethernet interface:
Step
1. Enter system view.
2. Enter Ethernet
interface view.
3. Configure physical
state change
suppression.

Configuring dampening on an Ethernet interface

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.
Suppressing interface state change events protects the system resources.
If an interface is not dampened, its state changes are reported. For each state change, the system
also generates an SNMP trap 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 trap and log messages.
Parameters
•
Penalty—The interface has an initial penalty of 0. When the interface flaps, the penalty
increases by 1000 for each down event. It does not increase for up events.
•
Ceiling—The penalty stops increasing when it reaches the ceiling.
•
Suppress-limit—The accumulated penalty that triggers the device to dampen the interface. In
dampened state, the interface does not report its state changes to the CPU. For state change
events, the interface only generates SNMP traps and log messages.
•
Reuse-limit—When the accumulated penalty decreases to this reuse threshold, the interface is
not dampened. Interface state changes are reported to the upper layers. For each state change,
the system also generates an SNMP trap and log message.
•
Decay—The amount of time (in seconds) after which a penalty is decreased.
•
Max-suppress-time—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 ceiling is equal to 2
Figure 1 shows the change rule of the penalty value. The lines t
end time of the suppression, respectively. The period from t
to t indicates the max-suppress-time, and t
1
Command
system-view
interface interface-type
interface-number
link-delay [ msec ]
delay-time [ mode { up |
updown }]
(Max-suppress-time/Decay)
× reuse-limit. It is not user configurable.
to t
1
8
Remarks
N/A
N/A
By default, physical state change suppression on
an Ethernet interface is disabled.
and t
0
to t indicates the suppression period, t
0 2
indicates the complete decay period.
2
indicate the start time and
2
0