Duplicate mac address

hi, how to make an alert for duplicate mac addresses on all network switches

What is the definition of a duplicate MAC address? It’s highly unlikely you’ll be able to detect this, since if you have two switches connected together (same L2 domain) they will necessarily both learn the same MACs.


virtual machine did not up because of the same mac with another virtual machine, I would like to track such duplication, we collect the fdb table on the switches, as I understand it, can I write a sql query to search for duplicates?

the virtual machine did not up because of the same mac with another virtual machine, I would like to track such duplication, we collect the fdb table on the switches, as I understand it, can I write a sql query to search for duplicates?

You’re not going to be able to do it that way. The switch itself will only put a given MAC address into its FDB table once - it might flap between two different ports as packets are received from the conflicting VMs, but at the point when LibreNMS polls the FDB table it will only see it on one or other of the ports so you won’t be able to query the DB for that.

meaning if duplicate mac appeared on different switches

Ah but are those switches connected to each other?

variably, I understand that you want to say that I will not see a flapping mac, but I need to search the entire network due to a hypervisor bug that can generate the same mac, plus libra keeps a table for a while, so theoretically you can even see it on one switch in the database libra

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