Configuring link dampening and alarms on ICX 7150 devices

Link dampening can help minimize outages due to microflaps. Microflaps can cause Layer 2 and Layer 3 reconvergence, resulting in outages lasting several minutes. When link dampening is configured, microflaps can be monitored and ignored for a configured period to prevent unnecessary outages. When link dampening and alarms are configured with the linkdampen command, you can monitor the link for flaps and determine when to bring the link down.

All RUCKUS ICX devices support the linkdampen command, which enables link dampening with configurable sampling periods on a designated port. Microflaps detected on the port and related changes in state are reported through system logs and in show interfaces ethernet command output so you can determine when a response is necessary.

Note: Link dampening may cause momentary traffic loss, convergence issues, and other side effects and should be used only when required.

Link dampening can be applied to any port, including stacking and data ports. When the linkdampen command is applied to a port in a LAG interface, the configuration is applied to all ports on the LAG.

To configure link dampening with alarms and the desired sampling period on a FastIron device, perform the following steps.

  1. Enter global configuration mode. 
    device# configure terminal
device(config)#
  2. Enter the linkdampen command as shown in the following example. After the keyword interval, enter a value from 1 through 4 to indicate the number of 250 millisecond segments to include in the sampling period. Include the port number on which link dampening is to be configured after the keyword ethernet.
    The following sampling intervals are available:
    • 1: 250 ms
    • 2: 500 ms
    • 3: 750 ms
    • 4: 1 second
    Note: The recommended sampling period is 1 second (interval value set to 4).
    Note: The linkdampen command can coexist on the same interface with the link-error-disable command. 
    device(config)# linkdampen interval 1 ethernet 1/1/1
***CAUTION Link-Dampening may cause momentary traffic loss,
may cause status convergence issues and other side effects.
Use Link-Dampening only when required.
Recommended usage Link-Dampening interval 4 - 1 second.

    The example enables link dampening on Ethernet port 1/1/1 and sets the sampling interval to 1 (250 milliseconds).

  3. (Optional) To confirm the configuration, enter the show running-config command. 
    device(config)# show running-config 
Current configuration:
!
ver 08.0.70cT213
!
stack unit 1
  module 1 icx7150-48pf-poe-port-management-module
  module 2 icx7150-2-copper-port-2g-module
  module 3 icx7150-4-sfp-plus-port-40g-module
  stack-port 1/3/3
!
!
linkdampen interval 1 ethernet 1/1/1     <--- link dampening configuration for Ethernet port 1/1/1with a sampling interval of 250 milliseconds
logging console
!                                                                 
!
  4. To check the link dampening configuration and any related microflaps or state changes that have been recorded, enter the show interfaces ethernet command followed by the port number as shown in the following example. 
    device(config)# show interfaces ethernet 1/1/1
GigabitEthernet1/1/1 is up, line protocol is up 
  Port up for 8 minute(s) 40 second(s) 
  Hardware is GigabitEthernet, address is 609c.9ffe.03cc (bia 609c.9ffe.03cc)
  Configured speed auto, actual 1Gbit, configured duplex fdx, actual fdx
  Configured mdi mode AUTO, actual MDIX
  Member of L2 VLAN ID 1, port is untagged, port state is FORWARDING
  BPDU guard is Disabled, ROOT protect is Disabled, Designated protect is Disabled
  Link Error Dampening is Disabled
  STP configured to ON, priority is level0, mac-learning is enabled
  Openflow is Disabled, Openflow Hybrid mode is Disabled,  Flow Control is config enabled, oper enabled, negotiation disabled
  Mirror disabled, Monitor disabled
  Mac-notification is disabled
  Link Micro Flap Dampening is enabled   <--- Link dampening enabled on Ethernet port 1/1/1
  Damping Interval:250 msecs  Total Microflaps:0  <--- No microflaps during sampling period
  !
  !
  !

The following example configures link dampening for port 1/1/1. It sets the sampling interval to a value of 1 (which represents one interval of 250 milliseconds). The configuration is confirmed in output for the show running-config command and detailed in output for the show interface ethernet 1/1/1 command. 

device# configure terminal
device(config)# linkdampen interval 1 ethernet 1/1/1
***CAUTION Link-Dampening may cause momentary traffic loss,
may cause status convergence issues and other side effects.
Use Link-Dampening only when required.
Recommended usage Link-Dampening interval 4 - 1 second.
device(config)# show running-config 
Current configuration:
!
ver 08.0.70cT213
!
stack unit 1
  module 1 icx7150-48pf-poe-port-management-module
  module 2 icx7150-2-copper-port-2g-module
  module 3 icx7150-4-sfp-plus-port-40g-module
  stack-port 1/3/3
!
!
linkdampen interval 1 ethernet 1/1/1     <--- link dampening configuration for Ethernet port 1/1/1with a sampling interval of 250 milliseconds
logging console
!                                                                 
!

device(config)# show interfaces ethernet 1/1/1
GigabitEthernet1/1/1 is up, line protocol is up 
  Port up for 8 minute(s) 40 second(s) 
  Hardware is GigabitEthernet, address is 609c.9ffe.03cc (bia 609c.9ffe.03cc)
  Configured speed auto, actual 1Gbit, configured duplex fdx, actual fdx
  Configured mdi mode AUTO, actual MDIX
  Member of L2 VLAN ID 1, port is untagged, port state is FORWARDING
  BPDU guard is Disabled, ROOT protect is Disabled, Designated protect is Disabled
  Link Error Dampening is Disabled
  STP configured to ON, priority is level0, mac-learning is enabled
  Openflow is Disabled, Openflow Hybrid mode is Disabled,  Flow Control is config enabled, oper enabled, negotiation disabled
  Mirror disabled, Monitor disabled
  Mac-notification is disabled
  Link Micro Flap Dampening is enabled   <--- Link dampening enabled on Ethernet port 1/1/1
  Damping Interval:250 msecs  Total Microflaps:0  <--- No microflaps during sampling period
  Not member of any active trunks
  Not member of any configured trunks
  No port name
  IPG MII 0 bits-time, IPG GMII 0 bits-time
  MTU 1500 bytes, encapsulation ethernet
  MMU Mode is Store-and-forward
  300 second input rate: 967999344 bits/sec, 202341 packets/sec, 99.85% utilization
  300 second output rate: 967999352 bits/sec, 202341 packets/sec, 99.85% utilization
  105261644 packets input, 62946463112 bytes, 0 no buffer
  Received 105261643 broadcasts, 0 multicasts, 0 unicasts         
  0 input errors, 0 CRC, 0 frame, 0 ignored                       
  0 runts, 0 giants                                               
  105261789 packets output, 62946549822 bytes, 0 underruns
  Transmitted 105261788 broadcasts, 0 multicasts, 0 unicasts
  0 output errors, 0 collisions
  Relay Agent Information option: Disabled
  Protected: No
  MAC Port Security: Disabled

 This port is not being monitored for queue drops 
Egress queues:
Queue counters	  Queued packets	Dropped Packets
         0           105267070             1168968
         1                   0                   0
         2                   0                   0
         3                   0                   0
         4                   0                   0
         5                  23                   0
         6                   0                   0
         7                   0                   0
Parent topic: Basic port parameter configuration