Ethernet Switches & Routers

Occasional Contributor
Posts: 6
Registered: ‎07-24-2013

How to verify whether interface flapped or not?

Hi Team,

Could you please let us know a command to verify last interface flap?

Here is my Sw details:

show version

  SW: Version 04.3.02cT7e1 Copyright (c) 1996-2008 Foundry Networks, Inc.

      Compiled on May 26 2010 at 16:40:58 labeled as FGS04302c

      (2956138 bytes) from Primary FGS04302c.bin

      BootROM: Version 05.0.00T7e5 (FEv2)

  HW: Stackable FLS624

Thank you,

P Phani.

Posts: 152
Registered: ‎10-05-2010

Re: How to verify whether interface flapped or not?

Hi Phani,

Have you configured your switch with "port flap dampening" to limit the number of port state transitions on an interface? If so, you will find that in syslog entries.

If the threshold for the number of times that a port’s link toggles from “up” to “down” then “down” to “up” has been exceeded, the following Syslog message is displayed:

0d00h02m10s:I:ERR_DISABLE: Link flaps on port ethernet 16 exceeded threshold;

port in err-disable state



Super Contributor
Posts: 1,087
Registered: ‎12-13-2009

Re: How to verify whether interface flapped or not?

You will see port up / down messages by default via local log (and syslog / SNMP if configured).

Also if you use link-error-disable as Sharan says above you can use the command "show link-error-disable all"


  DECIMAL   max number of state toggles (valid 1 - 50)

SSH@swtich(config-if-e1000-1/1/18)#link-error-disable 2

  DECIMAL   sampling period in seconds (valid 1 - 65535)

SSH@swtich(config-if-e1000-1/1/18)#link-error-disable 2 10

  DECIMAL   waiting period in seconds (valid 0 - 65535, 0 = forever)

SSH@swtich(config-if-e1000-1/1/18)#link-error-disable 2 10 0

SSH@swtich(config-if-e1000-1/1/18)#sh link-error-disable all

Port -----------------Config--------------- ------Oper----

  #       Threshold  Sampling-Time Shutoff-Time   State  Counter

------- ---------  -------------  ------------ -----  -------

1/1/18            2             10    Indefinite    Idle N/A




Occasional Visitor
Posts: 1
Registered: ‎11-05-2015

Re: How to verify whether interface flapped or not?

Hi Michael,


we were seeing some issue with one particular port, plan to monitor port why it was flaping but i couldn't find command "sh link-error-disable all" in  BigIron RX-16 CHASSIS. is there any other command we have to use in BigIron chassis?  


telnet@SW(config-if-e1000-7/28)#show link
link-fault-signaling show 802.3ae 10G Link Fault Signaling
link-keepalive Show link-keepalive information
telnet@SW(config-if-e1000-7/28)#show link




Posts: 47
Registered: ‎08-03-2015

Re: How to verify whether interface flapped or not?



If you haven't configured any of the above configurations, simply go to logs by switch#show logging command and you can see there that interface status is frequently changing.


for VDX switches use command switch#show logging raslog




Umair Khan Patel

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