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%SW_MATM-4-MACFLAP_NOTIF: Host 4025.c225.d9f0 in vlan 16 is flapping between port Gi1/0/27 and port Gi1/0/12

Hi all ,

        we have a network with CORE4507 access 2960x24port+4portSFP

 

CORE configured to allowed vlan all till access switch SFP interface Gi1/0/27 when i show log to switch i found error below.

 

\%SW_MATM-4-MACFLAP_NOTIF: Host 4025.c225.d9f0 in vlan 16 is flapping between port Gi1/0/27 and port Gi1/0/12

 

In access switch port Gi1/0/12 and port Gi1/0/24 is configured as trunk and WAP121 wirelessAP is connected tow SSID,s are configured  SSID1=VLAN 10 SSID2=VLAN16 

interface GigabitEthernet1/0/12
 switchport trunk allowed vlan 10,16
 switchport mode trunk

interface GigabitEthernet1/0/24
 switchport trunk allowed vlan 10,16
 switchport mode trunk

Any Help

 

Regards

4 REPLIES
Cisco Employee

Hi, Please provide config of

Hi,

 

Please provide config of port Gig1/0/27 and login to device connected to Gig1/0/27 and check from which port you are learning MAC in question. MAC flap shows layer2 loop, by tracing MAC learning on each device we can get some idea same MAC is being learned on two ports.

 

Regards,

Akash

New Member

Hello Akash,             

Hello Akash,

               Thanks for repley port 1/0/27 is configured as trunk and allowed Vlan All

interface GigabitEthernet1/0/27
 switchport mode trunk

this is sh cdp ne

 

V35#sh cdp neighbors 
Capability Codes: R - Router, T - Trans Bridge, B - Source Route Bridge
                  S - Switch, H - Host, I - IGMP, r - Repeater, P - Phone, 
                  D - Remote, C - CVTA, M - Two-port Mac Relay 

Device ID        Local Intrfce     Holdtme    Capability  Platform  Port ID
CORE1            Gig 1/0/27        176             R S I  WS-C4507R Gig 1/23

 

Regards

  

Cisco Employee

 You need to login to CORE1

 

You need to login to CORE1 (4500) and check from which interface you are learning the MAC 4025.c225.d9f0 and why. Is it expected to traffic from the mac to come on 4500. Try to draw a layer2 topology from V35 to device (having mac 4025.c225.d9f0) and check where l2 loop is possible.

 

-Akash

Hall of Fame Super Gold

Two links from the 4500 going

Two links from the 4500 going to 2960X but both links are NOT an Etherchannel?

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