MAC address table

Products cnMatrix
#1

Hi.

We have two EX2016M-P with 4.2.1-r5 running and I suspect there are problems with clearing MAC address table. When I have one device connected on one VLAN and I change it to different VLAN, it won’t clear entry in MAC address table on old VLAN. Device won’t get IP address on old or new VLAN.
If I reload switch with the same configuration, it starts working instantly. If I check MAC address table when it works, I see MAC address entry only on new VLAN - as it should be.

Device behind switch is XV2-2 (out of the box or already configured).

We are running PVRSTP, if it matters.

I am not sure that all my findings are correct, but there is definetly something happening.
I can’t find command to clear mac address table entry to troubleshoot further.

Ask me anything you need to know, to check anything further.

Kind regards

#2

Hi AnzeZ,

The switch is using IVL (Independent VLAN Learning) mode, therefore the same MAC can be learned on different VLANs in the FDB table. Forwarding decision is based on MAC and VLAN. That said, we need to investigate why the device did not get ip address when the device sends DHCP Discovery on the new VLAN. Can you capture the packets between the switch and dhcp server?

The mac in the old vlan would be aged out after about 5 minutes of no activity. You can also clear the mac address as shown:

config terminal
clear mac-address-table dynamic <vlan|interface>

Regards