Mac Address Flapping

TroyV
Here to help

Mac Address Flapping

I have connected a new device that allows for video conferencing and it is reporting MAC address flapping. When I looked this up I have seen that this will happen if a device from one port is moved to another quickly. This is setup as an access port on VLAN 200 and for some reason it keeps jumping around to different vlans in the logs which I will post below. Does anyone have any idea why this would be happening? 

 

Jun 14 12:39:13IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 10, port: 68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/26
Jun 14 12:37:31IDF-U20 MAC address flappingmac: E2:26:16:C0:29:83, vlan: 100, port: 68:3A:1E:A5:70:26/48,68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/52
Jun 14 12:29:01IDF-U20 MAC address flappingmac: 1A:E1:2F:B4:2B:4B, vlan: 100, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/14,68:3A:1E:A5:70:26/42
Jun 14 12:29:00IDF-U20 MAC address flappingmac: 1A:E1:2F:B4:2B:4B, vlan: 8, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/14,68:3A:1E:A5:70:26/42
Jun 14 12:28:59IDF-U20 MAC address flappingmac: 1A:E1:2F:B4:2B:4B, vlan: 3, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/14,68:3A:1E:A5:70:26/42
Jun 14 12:20:21IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 10, port: 68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/46
Jun 14 12:15:35IDF-U20 MAC address flappingmac: 32:E1:2F:C8:A8:88, vlan: 8, port: 68:3A:1E:A5:70:26/38,68:3A:1E:A5:70:26/52,68:3A:1E:A5:70:26/36
Jun 14 12:15:34IDF-U20 MAC address flappingmac: 32:E1:2F:C8:A8:88, vlan: 100, port: 68:3A:1E:A5:70:26/38,68:3A:1E:A5:70:26/52,68:3A:1E:A5:70:26/36
Jun 14 12:15:34IDF-U20 MAC address flappingmac: 32:E1:2F:C8:A8:88, vlan: 3, port: 68:3A:1E:A5:70:26/38,68:3A:1E:A5:70:26/52,68:3A:1E:A5:70:26/36
Jun 14 12:15:21IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 8, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:15:20IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 3, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:15:20IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 10, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:15:10IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 8, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:15:09IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 10, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:15:09IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 3, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:15:00IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 8, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:14:59IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 10, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:14:59IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 3, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:14:50IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 8, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:14:49IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 10, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:14:49IDF-U20 MAC address flappingmac: 5E:9F:EC:94:C2:AA, vlan: 3, port: 68:3A:1E:A5:70:26/44,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/44
Jun 14 12:13:11IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 3, port: 68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/14
Jun 14 12:13:11IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 8, port: 68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/14
Jun 14 12:13:11IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 10, port: 68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/14
Jun 14 12:11:54IDF-U20 MAC address flappingmac: 32:E1:2F:C8:A8:88, vlan: 100, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/42
Jun 14 12:11:44IDF-U20 MAC address flappingmac: 32:E1:2F:C8:A8:88, vlan: 100, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/46,68:3A:1E:A5:70:26/42
Jun 14 12:09:35IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 8, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42
Jun 14 12:09:35IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 3, port: 68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42
Jun 14 12:09:19IDF-U20 MAC address flappingmac: EE:15:84:67:A8:B1, vlan: 8, port: 68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/26
Jun 14 12:09:18IDF-U20 MAC address flapping

mac: EE:15:84:67:A8:B1, vlan: 3, port: 68:3A:1E:A5:70:26/26,68:3A:1E:A5:70:26/42,68:3A:1E:A5:70:26/26

 

I also see the below happening. This is an end device so not sure why the port would be shutting down.

Jun 14 11:59:20IDF-U20 Port status changeport: 3, old: 1Gfdx, new: down
Jun 14 11:53:54IDF-U20 Port status changeport: 3, old: down, new: 1Gfdx
Jun 14 11:53:50IDF-U20 Port status changeport: 3, old: 1Gfdx, new: down
Jun 14 11:53:48IDF-U20 Port status changeport: 3, old: down, new: 1Gfdx
Jun 14 11:53:02IDF-U20 Port status changeport: 3, old: 1Gfdx, new: down
Jun 14 11:53:01IDF-U20 Port status changeport: 3, old: down, new: 1Gfdx
Jun 14 11:52:18IDF-U20 Port status changeport: 3, old: 1Gfdx, new: down
Jun 14 11:42:42IDF-U20 Port status changeport: 3, old: down, new: 1Gfdx
Jun 14 11:42:37IDF-U20 Port status changeport: 3, old: 1Gfdx, new: down
Jun 14 11:42:25IDF-U20 Port status changeport: 3, old: down, new: 1Gfdx

 

I tried looking up information on both issues and I can't find anything that seems to fit the issue I am experiencing. Any help would be greatly appreciated.

5 REPLIES 5
cmr
Kind of a big deal
Kind of a big deal

What is connected to port 3?  The devices flapping in different VLANs seem to be different devices.  With one being in VLANs 3 and 8 and the other being in VLAN 100.

TroyV
Here to help

It is this one single device that is made by Neat called the Neatbar that works in conjunction with a tablet to provide video conferencing for a conference room.

 

The ethernet drop runs from this device all the way to the patch panel and is plugged into port 3, which I moved to another switch on port 28.Screen Shot 2022-06-14 at 2.58.54 PM.pngScreen Shot 2022-06-14 at 3.00.50 PM.png

 

I know how it looks, but this is one device, connected via ethernet, making these jumps, which makes no sense to me. I moved the connection to another switch and the problem follows. Below is the port config and the new logs.

 

r0ssc0
Conversationalist

Hi Troy,  The most usual case for mac flapping in Meraki is wireless devices jumping between access points.  But if the mac is an ethernet mac then the last time I had this was when the customer inadvertently connected the vlans together.

Yeah, I have seen it on AP's but on switches is new for me. Thank you for that direction; I will look into seeing if the VLANS are able to talk to each other; or perhaps just layer 3 isolate it and test from there.

TroyV
Here to help

I have found that there are two issues here which one was an end device being problematic; that was the port status change. 

 

The second issue is a switch in the network that is the wrong priority and doing a packet trace we found that was the cause of the mac address flap. Upon further investigation and adjusting the priorities we found this issue to have gone away.

 

Appreciate everyones help!

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