08-29-2014 05:51 AM - edited 03-07-2019 08:34 PM
Dear All,
I have a VERY strange problem on our offices. I'm going report the most simple case in order to let you understand better.
One 2960 Switch
One 2901 Router
Three PCs
Router and PCs are connected using a single straigh-throu cable.
On our swith we find sometimes the following warning:
Aug 29 12:21:28.247: %SW_MATM-4-MACFLAP_NOTIF: Host e02f.6dc1.b0f8 in vlan 2 is flapping between port Fa0/10 and port Fa0/24
Port 10 is phisically connected to one PC
Port 24 is phisically connected to the router
There are no loops on the switch.
This problem happens in other 10/12 offices with more complex infrastructure but the warning is always the same:
The Default Gatway MAC address flaps from its port to a PC port.
Obviously we already checked the PC and there are no network devices between the NIC and wall port.
Paolo