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Why am I receiving duplicate MAC addresses using a bridged adapter in VMWare Workstation

Posted on 2016-08-02
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Last Modified: 2016-08-02
hello,

I have VMWare Workstation 12 setup on my laptop with a windows 2008 R2 VM which is using a bridged network adapter. The host(laptop) has a different IP than the VM. Both IP's are in the same subnet.

At one point it was all working fine. I would connect via RDP to the host and RDP to the VM accordingly. However, now all of a sudden when I try to connect to the VM, I instead connect to the host.

Further looking at the VM, I am receiving an IP conflict message. When I look at the arp table on the switch i see that both IP's from the host and VM show the same MAC addr

sw-corp-core01#show arp | i c7f8
Internet  10.30.10.40            12   206a.8afd.c7f8  ARPA   Vlan10  <== IP of VM
Internet  10.30.10.62             0   206a.8afd.c7f8  ARPA   Vlan10 <== IP of Host

This is weird because the VM has the virtual MAC and the host, well it has its own physical mac. Yet on the switch both show the same MAC even though I have 2 different DNS entries on my domain controller.

Anyways, does this behavior sound right? I thought that the MAC address of the VM is suppose to be the actual virtual MAC even though I am bridging with the physical NIC of the host. Again, at one point I was connecting to each server individually/simultaneously.

Many thanks in advance.

t
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Question by:tobe1424
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LVL 119
ID: 41739327
However, now all of a sudden when I try to connect to the VM, I instead connect to the host.

even if you use both IP Addresses ?
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by:tobe1424
ID: 41739334
Yes. I forgot to mentioned this. When i use the IP of the VM, I connect to the host.
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John Hurst earned 500 total points
ID: 41739335
If you are using Bridged Networking, you should get a different IP in the same subnet.

You might try running the VMware Networking Editor (Run as Administrator) and reset the network components. Restart the computer. Then run TCP/IP Reset on the Host and on the Guest machine.

Open cmd.exe with Run as Administrator
Then  netsh int ip reset c:\resetlog.txt

Restart the Host and the restart the Guest after you have reset TCP/IP.
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LVL 119
ID: 41739375
so both IP Addresses connect to the Host ?

what is the MAC Address of the VM, and can you ping that ?
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by:tobe1424
ID: 41739393
I just perform the netsh reset and i am assigning the IP's again to then test.

Andrew, that is correct. I can ping the IP of the VM but it is recognized as the IP of the host for some reason. The MAC of the VM ends with 64:7A

But when I ping the IP of the VM and issue a 'arp -a' command I see the MAC of the host instead of the VM. this is the case from both the switch and my workstation/pc.

but right now I am re-ip'ing after the netsh reset..standby..
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Author Comment

by:tobe1424
ID: 41739403
seems like the IP and MAC assignment is correct. arp -a for both IP's return the appropriate MAC.

testing RDP connections..
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Author Comment

by:tobe1424
ID: 41739413
at first the RDP connections did not work. i had to go into the Remote session host config and recreate the connections.

Thanks guys!
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LVL 93

Expert Comment

by:John Hurst
ID: 41739463
You are very welcome and I was happy to help.
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