Cannot be added to the FDB (Hash Table Collision)

[Informatique Joskin]

Hello Cisco Community,

Starting today, I've seen this log message appearing a lot in my logs. From what I've read, it's either a duplicate MAC address or a loop in the network. We have checked for loops and we didn't find any. And this can't be a duplicate MAC address as we haven't added any new device with one of the three MAC addresses in the logs (which have been censured in the logs).

We have also tried restarting one switch that has the problem, but the log comes right after rebooting, but strangely with another MAC address. We also have checked that the switches in question are up to date and that's the case.

The models of switch which causes the issues are SG250-26P, SG250-50P, CBS250-24P-4X and CBS350-8FP-E-2G.

Now, we don't have any more ideas and I come to you to help me find a solution as this problem is strange. If you need any more information, you can ask me.

Thanks in advance,

Nicolas

Here are the logs:

2023-11-29 10:35:58.655586973 +0100 CET - B.B.B.B: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi11 ,MAC bb:bb:bb:bb:bb:bb : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:55.496853372 +0100 CET - E.E.E.E: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi10 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:37.878455634 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:33.881538083 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:22.942066935 +0100 CET - H.H.H.H: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:22.94204673  +0100 CET - G.G.G.G: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:22.940304801 +0100 CET - F.F.F.F: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi1  ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:21.941065498 +0100 CET - F.F.F.F: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi1  ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:21.939379333 +0100 CET - H.H.H.H: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:21.939238477 +0100 CET - G.G.G.G: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:35:21.939217639 +0100 CET - I.I.I.I: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi26 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:34:53.729429394 +0100 CET - B.B.B.B: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi11 ,MAC bb:bb:bb:bb:bb:bb : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:34:33.589012868 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:34:32.534975678 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:34:28.078285406 +0100 CET - D.D.D.D: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision), aggregated (1)  
2023-11-29 10:34:20.452172222 +0100 CET - I.I.I.I: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi26 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision), aggregated (5)  
2023-11-29 10:33:50.713147324 +0100 CET - B.B.B.B: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi11 ,MAC bb:bb:bb:bb:bb:bb : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:33.88289355  +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:32.095914155 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:22.933224234 +0100 CET - H.H.H.H: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:22.932687082 +0100 CET - G.G.G.G: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:22.931017323 +0100 CET - F.F.F.F: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi1  ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:21.931564042 +0100 CET - D.D.D.D: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:21.931533885 +0100 CET - H.H.H.H: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:21.931396632 +0100 CET - G.G.G.G: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi50 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:21.929768058 +0100 CET - F.F.F.F: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi1  ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:33:00.166539423 +0100 CET - E.E.E.E: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi10 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:32:46.907933369 +0100 CET - B.B.B.B: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi11 ,MAC bb:bb:bb:bb:bb:bb : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:32:32.221748465 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:32:31.212301721 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:32:21.907078535 +0100 CET - D.D.D.D: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC cc:cc:cc:cc:cc:cc : Cannot be added to the FDB (Hash Table Collision), aggregated (5)  
2023-11-29 10:32:09.004079516 +0100 CET - C.C.C.C: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi48 ,MAC bb:bb:bb:bb:bb:bb : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:31:43.417676811 +0100 CET - B.B.B.B: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi11 ,MAC bb:bb:bb:bb:bb:bb : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:31:31.406737586 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)  
2023-11-29 10:31:30.320129841 +0100 CET - A.A.A.A: <189>%2SWMACTBL-N-PORTMACHASHFAILED: Port gi49 ,MAC aa:aa:aa:aa:aa:aa : Cannot be added to the FDB (Hash Table Collision)

[pieterh]

what version are you running ?
could be : Cisco Bug: CSCvy66085 - SG350X-48MP Hash Table Collision

[silronatan]

Hello!

Got the solution for this issue? I'm facing the same problem!

[Informatique Joskin]

Hello,

Sadly, we didn't have found any solution. What we finally did to "solve" this problem is to remove the device with the MAC address that caused the PORTMACHASHFAILED error. Once we removed it, the problem was "solved".

After that, to be sure it wasn't a duplicate MAC, we checked the MAC address table and the MAC wasn't in any of the switch table. So we can rule out the possibility it was a duplicate. So most probably a bug.

Regards,

Nicolas

[silronatan]

Hello Nicolas,

Thank you for your response!

In my case, the MAC addresses are from wireless devices. As it's a school environment, I believe there's nothing I can do about it. Since it's a bug, I'll simply ignore this log message.

Appreciate the assistance!