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MATM log warnings: MAC flapping

Hello!

Please, take a look at the attached scheme.

Client has a VLAN link through the provider network.

Connection points (to SW-1 and SW-4) are geographically distributed (about 400 km).

All provider switches are L3, interfaces Gi0/1 and Gi0/2 on SW-1 and SW-4 are as configured L2 access switchports.

Here are some stats for border switches:

SW-1#show mac-address-table interface GigabitEthernet 0/1
          Mac Address Table
-------------------------------------------
Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
4    001b.2bxx.xxxx  DYNAMIC     Gi0/1
4    001c.f6yy.yyyy     DYNAMIC     Gi0/1
Total Mac Addresses for this criterion: 2

SW-4#sh mac-address-table interface gigabitEthernet 0/2
          Mac Address Table
-------------------------------------------

Vlan    Mac Address       Type        Ports
----    -----------       --------    -----
4      0000.cd1f.ad2f    DYNAMIC     Gi0/2
4      0000.cd33.85b5  DYNAMIC     Gi0/2
<............cut...........>

4      485b.3914.dde5  DYNAMIC     Gi0/2
Total Mac Addresses for this criterion: 179

On all switches (SW-2, SW-3,SW-4) except SW-1 logs are full of flap warnings:

SW-4#sh logging

<............cut...........>

Jul  2 02:39:22.165 MSD: %SW_MATM-4-MACFLAP_NOTIF: Host 001c.f6yy.yyyy in vlan 4 is flapping between port Gi0/2 and port Gi0/24
Jul  2 02:39:32.978 MSD: %SW_MATM-4-MACFLAP_NOTIF: Host
001c.f6yy.yyyy in vlan 4 is flapping between port Gi0/2 and port Gi0/24
Jul  2 02:39:59.366 MSD: %SW_MATM-4-MACFLAP_NOTIF: Host
001c.f6yy.yyyy in vlan 4 is flapping between port Gi0/2 and port Gi0/24

What could cause such appearance of one MAC (001c.f6yy.yyyy) on the Gi0/2 interface of SW-4 ?

What are the ways to:

1)block the appearance of that MAC on SW-4 Gi0/2 ?

2)supress appearance of MATM warnings in log ?

Client says that there could happen some looping on his backbone.

I also learned from previous discussiona, that a close to my case - there could be some concerns with PIX/ACA failover configuration.

Thanks.

Alex.

DAO21-RIPE
1 REPLY
Community Member

Re: MATM log warnings: MAC flapping

still up

DAO21-RIPE
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