Switching

[bava_ccna]

i am getting this error on my L3 switch

'Host 02:01:00:00:00:00 in vlan 1 is flapping between port Gi2/14 and port Gi2/7'

how to solve this problem? why it happens?

Thanx in advance

Bava

[mohammedmahmoud]

Hi Bava,

Kindly check the below links for details, and keep in mind that this differs if the message appears for multiple MAC addresses as compared to just one MAC address.

http://www.cisco.com/en/US/products/hw/switches/ps4324/products_tech_note09186a008063c36f.shtml#cg1

http://www.cisco.com/en/US/products/hw/switches/ps663/products_tech_note09186a00801434de.shtml#subtopic1k

BR,

Mohammed Mahmoud.

[royalblues]

In addition to Mohammed's post, the Mac address that seem to be flapping is the one used by microsft for their NLB (multicast) service.

Trace the server via the ports mentiones and try disabling the service if it is not required on the particular server

HTH

Narayan

[mohammedmahmoud]

Hi,

Totally agree with Narayan (nice catch Narayan), NLB is probably sending it out on multiple ports from the server, or from multiple servers in a cluster, turning the service off if it is not used is the easy solution, if not an option then you'll need to search for a workaround from Microsoft side, and i believe that this issue was discussed and a workaround is available from Microsoft side.

BR,

Mohammed Mahmoud.