Flapping

Answered Question
Mar 27th, 2010

I have 2 port on my 4510R switch...  there is flapping going on between 2 ports in vlan one. both of these ports are connected to a cisco 4400 Wireless Controller.

There are no recommended solutions or reasons for why this is happening.  the only information displayed in the system message is the type of error if this can help

Explanation: not available

Recommended action: not available

type: C4K_EBM-4-HOSTFLAPPING

please adise to how to start troubleshooting the above message

thank you

Correct Answer by robmccam1 about 6 years 10 months ago

We saw this until we quit running in H-Reap.  Is the 4402 connected via a trunk or via access?  When the AP's are using H-Reap, a device that is in between the two devices will alternate between them and the switch will see that, causing the MAC-FLAP.

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 5 (1 ratings)
Loading.
Joe Clarke Sat, 03/27/2010 - 14:47

There is no show run here, but given your version of code, this syslog message means that a host has moved ports at least 4 times in a 15 second interval.  This message is disabled by default in 12.2(52)SG, but can be enabled when MAC address notifications are enabled.

--

Please support CSC Helps Haiti

https://supportforums.cisco.com/docs/DOC-8895

https://supportforums.cisco.com

Joe Clarke Mon, 03/29/2010 - 16:51

Given your software version, the config wasn't necessary.  As I said, the message indicates that a certain MAC address is switching between ports (at least four times in a 15 second window).  I'm not sure how your controllers are configured, but perhaps there is an issue there (e.g. maybe some virtual MAC is switching from controller to controller).

--

Please support CSC Helps Haiti

https://supportforums.cisco.com/docs/DOC-8895

https://supportforums.cisco.com

Correct Answer
robmccam1 Sun, 03/28/2010 - 14:47

We saw this until we quit running in H-Reap.  Is the 4402 connected via a trunk or via access?  When the AP's are using H-Reap, a device that is in between the two devices will alternate between them and the switch will see that, causing the MAC-FLAP.

Actions

This Discussion

Related Content