Simple question, do physical Macs accociated with port groups get masked on switches?

[lukeglazebrook]

This is sort of difficult to explain but I will try my best.  I have just resolved an issue related to VM connectivity with the network boys.  I supplied them with the physical Mac associated with VMNIC1 "00:18:FE:33:A4:47" I told them it was patched into port eight.  When they logged onto their switch they couldn't see it at all, eventually however when they tagged the port with VLAN 208 which happens to be one of the configured VM port groups with a VM on it they were suddenly able to see the Mac from the VM that routes via VMNIC1 "00:18:FE:33:A4:47".

For future reference so I can learn and better understand things going forward can anyone clarify how this works.  Does ESX hide/mask the physical Mac in favor of the Macs from VM's on this occasion it was an old ESX3.5 host but I assume 5.5 would have done the same?

[lakshya32 · Accepted solution]

Hi

Welcome to communities.

I think not only ESX hyper v too hide physicl MAC and all VNIC have unique MAC id

which play important role type cluster ,NLB configuration .

Its my practical experience.

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[krish290785]

The Virtual Machine is connected to one of the port on the portgroup. The portgroup  is just a part of vSwitch. The vSwitch is connected to physical NICS (VMNICS). The VMNICS will act as an uplink to the vSwitch and will carry any traffic out of them and passes to the external devices like switches. Since there is no concept of assigning the IP address to the virtual machine portgroups, the physical MAC doesn't come into picture.

Since an IP is assigned for Management network, you should be able to see the related vmnic mac on the switch to which it is connected.

[lukeglazebrook]

Thanks for clarifying this guys, just our of curiosity what would the network guys typically see if there happens to be multiple VM's on the port-group.  Would they see the first machine that came online?

[krish290785]

They should be able to see all the VMs mac addresses on the switch port to which the VMNIC for Virtual Machine Traffic is connected.