%SW_MATM-4-MACFLAP_NOTIF: Flapping Portchannel

[Pyie Phyo Htay]

Hello Members,

We are currently experiencing flapping issues on our C9300 stacking switches. These switches are running Cisco Network Advantage licenses with evaluations that have expired.

Currently, we are configuring the stacking mode, four Port-Channels, inter-VLAN routing, DHCP services, and trunks on these switches.
We are encountering Port-Channel flapping issues to the access switches. All Port-Channels are configured with PAgP for trunking, and the links are established using fiber/SFP media.

Please kindly see the below logs file information and please helps me to solve me issues.

*Jan 26 20:38:38.617: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.286f.fcc8 in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:39:00.034: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.2870.0d3f in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:39:06.073: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.209c in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:39:06.595: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.2870.1033 in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:39:06.904: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.286f.fcc8 in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:39:08.672: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1b30 in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:39:09.870: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1c5d in vlan 21 is flapping between port Po21 and port Po22
*Jan 26 20:39:10.024: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1d84 in vlan 21 is flapping between port Po21 and port Po23
*Jan 26 20:39:10.064: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1c4a in vlan 21 is flapping between port Po21 and port Po23
*Jan 26 20:39:10.672: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.17f9 in vlan 21 is flapping between port Po21 and port Po23
*Jan 26 20:39:11.216: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1b5d in vlan 21 is flapping between port Po21 and port Po23
*Jan 26 20:39:46.767: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.2870.11d8 in vlan 21 is flapping between port Po21 and port Po22
*Jan 26 20:39:47.815: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.2870.0d73 in vlan 21 is flapping between port Po21 and port Po20
*Jan 26 20:39:48.415: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1b2e in vlan 21 is flapping between port Po21 and port Po20
*Jan 26 20:40:37.525: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.286f.fcc8 in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:41:26.747: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.286f.fe6c in vlan 21 is flapping between port Po21 and port Po20
*Jan 26 20:41:43.699: %SW_MATM-4-MACFLAP_NOTIF: Host 2c3f.0bca.1c5d in vlan 21 is flapping between port Po21 and port Po22
*Jan 26 20:41:44.932: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.2870.1033 in vlan 21 is flapping between port Po21 and port Po24
*Jan 26 20:41:45.875: %SW_MATM-4-MACFLAP_NOTIF: Host f89e.286f.fcc8 in vlan 21 is flapping between port Po21 and port Po24

[Kasun Bandara]

@Pyie Phyo Htay hi what is the other end of your port channel? is it FW? or switch ? clustered? VPC?

[Pyie Phyo Htay]

Hi Kasun,

End of all port channel are only C1000 switches.

[Kasun Bandara]

@Pyie Phyo Htay do you have any backend connection the devices configured with Po24 and Po21

[Pyie Phyo Htay]

HI Kasun,

Here is my Port-channel configuration to Access switch, that are using connected with Fiber Cable to Access Switch. 

interface Port-channel20
description Connect_to_Ground_FL_SW
switchport trunk allowed vlan 21,31-35,40-56,90
switchport mode trunk

!
interface Port-channel21
description connect_to_1st_Floor
switchport trunk allowed vlan 21,31-35,41-56
switchport mode trunk

!
interface Port-channel22
description Connected_to_SVR_ASW
switchport trunk allowed vlan 20,21,31-35,41-56,90
switchport mode trunk

!
interface Port-channel23
description connect_to_3rd_Fl
switchport trunk allowed vlan 21,31-35,41-56
switchport mode trunk

!
interface Port-channel24
description Connected_to_4th_SW
switchport trunk allowed vlan 21,31-35,41-56,90
switchport mode trunk

interface GigabitEthernet1/0/15
description Ground_FL_Gi1/0/25
switchport trunk allowed vlan 21,31-35,40-56,90
switchport mode trunk
channel-group 20 mode desirable
!
interface GigabitEthernet1/0/16
description 1st_Floor_Gi1/0/25
switchport trunk allowed vlan 21,31-35,41-56
switchport mode trunk

channel-group 21 mode desirable
!
interface GigabitEthernet1/0/17
description 3rd_FL_gi1/25
switchport trunk allowed vlan 21,31-35,41-56
switchport mode trunk
channel-protocol pagp
channel-group 23 mode desirable
!
interface GigabitEthernet1/0/18
description 4th_Floor_Gi1/0/25
switchport trunk allowed vlan 21,31-35,41-56,90
switchport mode trunk
channel-group 24 mode desirable
!
interface GigabitEthernet1/0/19
description ASW_Gi1/0/25
switchport trunk allowed vlan 20,21,31-35,41-56,90
switchport mode trunk
channel-group 22 mode desirable

interface GigabitEthernet2/0/15
description Ground_FL_Gi1/0/26
switchport trunk allowed vlan 21,31-35,40-56,90
switchport mode trunk
channel-group 20 mode desirable
!
interface GigabitEthernet2/0/16
description 1st_Floor_Gi1/0/26
switchport trunk allowed vlan 21,31-35,41-56
switchport mode trunk
channel-group 21 mode desirable
!
interface GigabitEthernet2/0/17
description 3rd_FL_Gi1/26
switchport trunk allowed vlan 21,31-35,41-56
switchport mode trunk
channel-protocol pagp
channel-group 23 mode desirable
!
interface GigabitEthernet2/0/18
description 4th_Floor_Gi1/0/26
switchport trunk allowed vlan 21,31-35,41-56,90
switchport mode trunk
channel-group 24 mode desirable
!
interface GigabitEthernet2/0/19
description ASW_Gi1/0/26
switchport trunk allowed vlan 20,21,31-35,41-56,90
switchport mode trunk
channel-group 22 mode desirable

[balaji.bandi]

How is your Network Topology Looks like ? do you have any Loops in the connection 2 Switch each other using PO21 and 24 ?

Or any WLC Clients connected using PO21 and 24 - if this case its normal

If no Wireless Clients you need to investigate, Looks like you have lots of other MACs, this most likely STP Loops between these Switches.

Can you provide :all the switches

show cdp neigh

show spann sum

[Pyie Phyo Htay]

Hi Balaji,

Each Cisco Meraki AP is connected to an Access Switch (C1000), and these Access switches are connected to a DS Switch (C9300) with a Port-Channel.

It is normal ?

Thanks.

[balaji.bandi]

Pickup one of the  MAC address and investigate - if that is Wireless Client and they are roaming between Meraki AP - then that is normally you see that logs.

[Pyie Phyo Htay]

Hi Balaji,

In the log message, when the MAC address of the host 'f89e.286f.fcc8' is identified as coming from a wireless client user, should I consider it normal if the MAC address matches that of the user?

Thanks.

[balaji.bandi]

Sure that is normal and you can ignore it. 

If you are using syslog server - all the logs will be collect there so no action required - If you have too many logs then you can use "logging discriminator with mnemonics" to suppress the logs if you want to.

[MHM Cisco World]

If mac is wifi the it normal since wifi client is l2 roaming between different Ap

You can disable these log via below 

no mac address-table notification mac-move

MHM

[Pyie Phyo Htay]

HI MHM,

I do understand, Thanks for your explanation MHM and Balaji. 

[Pyie Phyo Htay]

Hi MHM,

Let me ask one question, these flapping log message are can impact to switch performance? (slowly or Hanging).

Thanks and waiting your answer.