Same MAC address in 2 different VLANs

krad kraduk at
Fri Jul 19 10:02:28 UTC 2013

I think you maybe ok. Ive just looked at my esx config and the esx
management interfaces use their own generated macs, not the physical
interfaces ones. All the vms obviously use generated macs as well.

However I only looked over it at a superficial level.

Have you considered using a tap or spare phyical interface on your flex box
and not linking it to the network?

On 19 July 2013 10:29, Olivier Nicole <Olivier.Nicole at> wrote:

> Hello,
> Could any one comment about the use of the same MAC address in 2
> separate VLANs?
> All my machines are connected to 2 VLANs (one public and one private)
> with no routing in between the VLANs.
> I used to run a FLEX license manager to a physical machine. When I
> virtualized that service, I had to use the MAC address of that physical
> machine for the virtual machine (FLEX is linked to the MAc address and I
> coul dnot issue new license as licensed the pproduct is not supported
> anymore). The virtual NIC that has the old MAC address is connected to
> the public VLAN.
> Now I want to reuse the physical machine as a VMware server. Dell nor
> VMware offer a solution to change the MAC address (like
> ifconfig em0 link xx:xx:xx:xx:xx:xx would do). So I plan to connect the
> NIC with the incriminated MAC to the private VLAN.
> Most (if not all) my servers are FreeBSD. Most will access the virtual
> machine running FLEX and may access the VMware server also. The servers
> are not VLAN aware.
> Will this be an issue?
> Best regars,
> Olivier
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