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Host is flapping between 2 ports on a switch.

nstr1
Beginner
Beginner

 

I have my switches connected as follows.

 

nstr1_0-1669843289633.png

 

But I've seen these logs (both on port-channels and interfaces) on both core and access.

Logs CORE

*Nov 29 15:41:05.226: %SW_MATM-4-MACFLAP_NOTIF: Host 827d.bb89.a409 in vlan 82 is flapping between port Po13 and port Po12
*Nov 29 15:41:52.325: %SW_MATM-4-MACFLAP_NOTIF: Host 827d.bb89.a409 in vlan 82 is flapping between port Po13 and port Po12
*Nov 29 15:42:48.384: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Po10 and port Po13
*Nov 29 15:42:50.432: %SW_MATM-4-MACFLAP_NOTIF: Host 827d.bb89.a409 in vlan 82 is flapping between port Po12 and port Po13
*Nov 29 15:43:16.832: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Po10 and port Po12
*Nov 29 15:44:03.633: %SW_MATM-4-MACFLAP_NOTIF: Host 827d.bb89.a409 in vlan 82 is flapping between port Po13 and port Po12
*Nov 29 16:02:35.558: %SW_MATM-4-MACFLAP_NOTIF: Host 827d.bb89.a409 in vlan 82 is flapping between port Po12 and port Po13
*Nov 29 16:38:15.743: %SW_MATM-4-MACFLAP_NOTIF: Host 4aa3.5a95.f9f0 in vlan 82 is flapping between port Po13 and port Po10
*Nov 29 16:39:37.420: %SW_MATM-4-MACFLAP_NOTIF: Host 4aa3.5a95.f9f0 in vlan 82 is flapping between port Po10 and port Po12
*Nov 29 16:42:30.999: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Po12 and port Po13

Logs Access

Nov 29 12:46:41.212: %SW_MATM-4-MACFLAP_NOTIF: Host 4aa3.5a95.f9f0 in vlan 82 is flapping between port Po1 and port Gi1/0/45
Nov 29 12:48:01.659: %SW_MATM-4-MACFLAP_NOTIF: Host 4aa3.5a95.f9f0 in vlan 82 is flapping between port Gi1/0/45 and port Gi1/0/48
Nov 29 12:51:30.979: %SW_MATM-4-MACFLAP_NOTIF: Host 8ed6.f69e.0f93 in vlan 82 is flapping between port Gi1/0/45 and port Gi1/0/43
Nov 29 12:52:02.059: %SW_MATM-4-MACFLAP_NOTIF: Host ea14.b885.f58b in vlan 82 is flapping between port Gi1/0/48 and port Gi1/0/45
Nov 29 13:04:48.998: %SW_MATM-4-MACFLAP_NOTIF: Host 6ace.c223.039f in vlan 82 is flapping between port Gi1/0/45 and port Gi1/0/43
Nov 29 13:08:19.377: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Gi1/0/45 and port Po1
Nov 29 13:10:50.054: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Gi1/0/45 and port Po1
Nov 29 13:12:44.975: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Po1 and port Gi1/0/45
Nov 29 13:13:02.738: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Gi1/0/45 and port Po1
Nov 29 13:13:16.935: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Gi1/0/45 and port Po1
Nov 29 13:13:31.095: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Po1 and port Gi1/0/45
Nov 29 13:13:47.550: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Gi1/0/45 and port Po1
Nov 29 13:15:01.793: %SW_MATM-4-MACFLAP_NOTIF: Host ca66.4352.a19c in vlan 82 is flapping between port Gi1/0/45 and port Po1
Nov 29 13:17:04.952: %SW_MATM-4-MACFLAP_NOTIF: Host 8ed6.f69e.0f93 in vlan 82 is flapping between port Gi1/0/45 and port Gi1/0/43
Nov 29 13:20:43.311: %SW_MATM-4-MACFLAP_NOTIF: Host ee64.6891.49ff in vlan 82 is flapping between port Po1 and port Gi1/0/48

Are the configuration of my port-channels and interfaces ok?

 

 

4 Replies 4

paul driver
VIP Expert VIP Expert
VIP Expert

Hello
Looking at your posted topology it suggests possible WLAN clients are roaming, Moving from an access-point on say switch X/switchport Gi1/0/45  then moving to a different  access-point located on say switchY via PO1, However given the default mac-address table aging timers(300 sec) applied to cisco switches they are reporting that the same mac-address is seen on differing switch/switchports


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

 

Should I make any changes to the timers???

The flapping is happening on VLAN 82 (it's the guest VLAN), shouldn't you also see flapping with other VLANs of some other SSID???

 

Hello
If the above logging doesnt relate to any wlan clients, than disable port Gi1/0/45 on the access switch and see if the flapping stops, as it may also suggest you have a loop.


Please rate and mark as an accepted solution if you have found any of the information provided useful.
This then could assist others on these forums to find a valuable answer and broadens the community’s global network.

Kind Regards
Paul

I have suggest you can if the mac address appear is for wireless to disable mac notification.  
this will remove any mac flapping notification for that host. 

it is suggestion. 
thanks 

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