cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
942
Views
0
Helpful
10
Replies
Highlighted
Beginner

mac flap

Dear all,

Please if you can helpme undertand, what could cause this problem, and what I have to do to investigate a solution.

It only happened once for a short time.

Please if you need more background do not hesitate to ask

Thanks

Best regards.

Samuel Domb

Log Buffer (4096 bytes):
00.1b01 in vlan 27 is flapping between port Gi0/41 and port Gi0/40
001349: Mar 9 16:43:34: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1a01 in vlan 2
6 is flapping between port Gi0/40 and port Gi0/46
001350: Mar 9 16:43:36: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1c01 in vlan 2
8 is flapping between port Gi0/40 and port Gi0/41
001351: Mar 9 16:43:36: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1502 in vlan 2
1 is flapping between port Gi0/40 and port Gi0/41
001352: Mar 9 16:43:36: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1b02 in vlan 2
7 is flapping between port Gi0/41 and port Gi0/40
001353: Mar 9 16:43:37: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1402 in vlan 2
0 is flapping between port Gi0/46 and port Gi0/40
001354: Mar 9 16:43:44: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1501 in vlan 2
1 is flapping between port Gi0/40 and port Gi0/41
001355: Mar 9 16:43:45: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1802 in vlan 2
4 is flapping between port Gi0/46 and port Gi0/40
001356: Mar 9 16:43:46: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1602 in vlan 2
2 is flapping between port Gi0/46 and port Gi0/40
001357: Mar 9 16:43:46: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1902 in vlan 2
5 is flapping between port Gi0/41 and port Gi0/40
001358: Mar 9 16:43:46: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1a01 in vlan 2
6 is flapping between port Gi0/46 and port Gi0/40
001359: Mar 9 16:43:47: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1502 in vlan 2
1 is flapping between port Gi0/40 and port Gi0/41
001360: Mar 9 16:43:47: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1702 in vlan 2
3 is flapping between port Gi0/40 and port Gi0/41
001361: Mar 9 16:43:47: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1901 in vlan 2
5 is flapping between port Gi0/40 and port Gi0/41
001362: Mar 9 16:43:47: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1b02 in vlan 2
7 is flapping between port Gi0/41 and port Gi0/40
001363: Mar 9 16:43:47: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1601 in vlan 2
2 is flapping between port Gi0/46 and port Gi0/40
001364: Mar 9 16:43:48: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1401 in vlan 2
0 is flapping between port Gi0/40 and port Gi0/46
001365: Mar 9 16:43:48: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1402 in vlan 2
0 is flapping between port Gi0/46 and port Gi0/40
001366: Mar 9 16:43:48: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1a02 in vlan 2
6 is flapping between port Gi0/40 and port Gi0/46
001367: Mar 9 16:43:53: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1b01 in vlan 2
7 is flapping between port Gi0/40 and port Gi0/41
001368: Mar 9 16:43:58: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1b02 in vlan 2
7 is flapping between port Gi0/40 and port Gi0/41
001369: Mar 9 16:43:59: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1a02 in vlan 2
6 is flapping between port Gi0/46 and port Gi0/40
001370: Mar 9 16:44:01: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1802 in vlan 2
4 is flapping between port Gi0/46 and port Gi0/40
001371: Mar 9 16:44:01: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1501 in vlan 2
1 is flapping between port Gi0/40 and port Gi0/41
001372: Mar 9 16:44:01: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1401 in vlan 2
0 is flapping between port Gi0/46 and port Gi0/40
001373: Mar 9 16:44:01: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1402 in vlan 2
0 is flapping between port Gi0/40 and port Gi0/46
001374: Mar 9 16:44:01: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1701 in vlan 2
3 is flapping between port Gi0/41 and port Gi0/40
001375: Mar 9 16:44:02: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1902 in vlan 2
5 is flapping between port Gi0/41 and port Gi0/40
001376: Mar 9 16:44:03: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1502 in vlan 2
1 is flapping between port Gi0/40 and port Gi0/41
001377: Mar 9 16:44:04: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1c01 in vlan 2
8 is flapping between port Gi0/41 and port Gi0/40
001378: Mar 9 16:44:04: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1c02 in vlan 2
8 is flapping between port Gi0/40 and port Gi0/41
001379: Mar 9 16:44:04: %SW_MATM-4-MACFLAP_NOTIF: Host 0007.b400.1602 in vlan 2
2 is flapping between port Gi0/46 and port Gi0/40
XCL_SW_CISCO2#

10 REPLIES 10
Highlighted
Rising star

What are the ports mentioned in the logs doing? 

What is plugged into them?

The most common cause of MAC flaps is when users roam between Wireless AP's but it could also mean a L2 switching loop. 

Highlighted

Thanks

Attached more info..

regards.

Samuel

Highlighted

Hi,

Based on the switch logs , the end device is flapping between two ports ...do the end device is configured with some software like teaming with Active/Active configuration. If yes , Try configuring the end device with Active/Passive configuration and see the behaviour.

Hope it Helps..

-GI

Highlighted

Hi, Thanks.

The two switches are connected to two routers in a GLBP configuration.

Regards.

Highlighted

Thanks Samuel, do you know if the MACs are associated to any end user device? 

show mac address-table | inc MAC-Address

show ip arp

I saw many MAC addresses on your output. Also verify if your STP is configured properly.




>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<
Highlighted

Hi Julio,

Those mac address 0008.b400.xxxx are mac address from the GLBP configuration in a router atacched to the f40 port of the switch.

The router is configured as a router on a stick configuration.

here the GLBP output:

GW1_XCL#sh glbp summ
GW1_XCL#sh glbp br
GW1_XCL#sh glbp brief
Interface   Grp  Fwd Pri State    Address         Active router   Standby router
Gi0/0.20    20   -   150 Active   192.168.20.1    local           192.168.20.19
Gi0/0.20    20   1   -   Listen   0007.b400.1401  192.168.20.19   -
Gi0/0.20    20   2   -   Active   0007.b400.1402  local           -
Gi0/0.21    21   -   130 Standby  192.168.21.1    192.168.21.19   local
Gi0/0.21    21   1   -   Active   0007.b400.1501  local           -
Gi0/0.21    21   2   -   Listen   0007.b400.1502  192.168.21.19   -
Gi0/0.22    22   -   150 Active   192.168.22.1    local           192.168.22.19
Gi0/0.22    22   1   -   Listen   0007.b400.1601  192.168.22.19   -
Gi0/0.22    22   2   -   Active   0007.b400.1602  local           -
Gi0/0.23    23   -   130 Standby  192.168.23.1    192.168.23.19   local
Gi0/0.23    23   1   -   Active   0007.b400.1701  local           -
Gi0/0.23    23   2   -   Listen   0007.b400.1702  192.168.23.19   -
Gi0/0.24    24   -   150 Active   192.168.24.1    local           192.168.24.19
Gi0/0.24    24   1   -   Listen   0007.b400.1801  192.168.24.19   -
Gi0/0.24    24   2   -   Active   0007.b400.1802  local           -
Gi0/0.25    25   -   130 Standby  192.168.25.1    192.168.25.19   local
Gi0/0.25    25   1   -   Active   0007.b400.1901  local           -
Gi0/0.25    25   2   -   Listen   0007.b400.1902  192.168.25.19   -
Gi0/0.26    26   -   150 Active   192.168.26.1    local           192.168.26.19
Gi0/0.26    26   1   -   Listen   0007.b400.1a01  192.168.26.19   -
Gi0/0.26    26   2   -   Active   0007.b400.1a02  local           -
Gi0/0.27    27   -   130 Standby  192.168.27.1    192.168.27.19   local
Gi0/0.27    27   1   -   Active   0007.b400.1b01  local           -
Gi0/0.27    27   2   -   Listen   0007.b400.1b02  192.168.27.19   -
Gi0/0.28    28   -   130 Standby  192.168.28.1    192.168.28.19   local
Gi0/0.28    28   1   -   Active   0007.b400.1c01  local           -
Gi0/0.28    28   2   -   Listen   0007.b400.1c02  192.168.28.19   -
Gi0/0.40    40   -   150 Active   192.168.40.1    local           unknown
Gi0/0.40    40   1   -   Active   0007.b400.2801  local           -
GW1_XCL#

Regards

Highlighted

Thanks

I think there are MAC addresses are used by GLBP for all the platforms, verify the MAC used:

sh glbp brief

https://supportforums.cisco.com/discussion/10559406/4-virtual-mac-addresses-glbp




>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<
Highlighted

Julio,

That's what I have already sent.

Regards.

Highlighted
VIP Mentor

Hi

Please verify this link, it could be related to a loop, You should identify the devices related to that MAC Addresses:

https://blogs.it.ox.ac.uk/networks/2011/02/04/mac-flaps-why-are-they-bad/

Hope it is useful.

:-)




>> Marcar como útil o contestado, si la respuesta resolvió la duda, esto ayuda a futuras consultas de otros miembros de la comunidad. <<
Highlighted

Thanks,

Those MAC addess came from a router configuration in glbp mode.

Regards

Content for Community-Ad