I encountered a problem with Windows 2008 R2 Hyper-V host. One of the machines that were migrated to a new Hyper-V host could not be accessed. The error we received was “was prevented from using MAC address because it is pinned to port” Packets were dropping like crazy (50%) to ONLY ONE VM, not all computers on the Hyper-V host. I found the virtual network adapter errors on the Hyper-V host. Below is the error.
To resolve this MAC conflict I regenerated the MAC address for the VM.
Here are the steps I completed:
- Turned off affected VM from the Hyper-V host.
- Changed MAC on the virtual network adapter from Dynamic to Static.
- Clicked the Generate button to generate new MAC.
- Started VM and tested RDP’ing into it successfully.
- Shut down VM.
- Changed virtual network adapter MAC back to Dynamic.
- Started VM and tested again successfully.
I found a Microsoft technet article describing how to recreate the virtual network adapter. I found that recreating the virtual network adapter entirely was not necessary. I only needed to regenerate the MAC address from Hyper-V SCVMM.
Windows Event Log Error (repeated hundreds of times in log)
Log Name: System
Source: VMSMP
Date: 1/24/2012 9:03:34 AM
Event ID: 28
Task Category: None
Level: Warning
Keywords: Classic
User: N/A
Computer: <computername>.<domain>.com
Description:
Port ‘SWITCHPORT-SM-E8D52D3C-3EAC-4353-A673-834EF735531F-0-1′ was prevented from using MAC address ’00-15-5D-01-2F-01’ because it is pinned to port ‘SCVMM-0BF79913-4339-‘.
Event Xml:
<Event xmlns=”http://schemas.microsoft.com/win/2004/08/events/event”>
<System>
<Provider Name=”VMSMP” />
<EventID Qualifiers=”32768″>28</EventID>
<Level>3</Level>
<Task>0</Task>
<Keywords>0x80000000000000</Keywords>
<TimeCreated SystemTime=”2012-01-24T14:03:34.933072500Z” />
<EventRecordID>653953</EventRecordID>
<Channel>System</Channel>
<Computer><computername>.<domain>.com </Computer>
<Security />
</System>
<EventData>
<Data>
</Data>
<Data>0</Data>
<Data>00-15-5D-01-2F-01</Data>
<Data>SWITCHPORT-SM-E8D52D3C-3EAC-4353-A673-834EF735531F-0-1</Data>
<Data>SCVMM-0BF79913-4339-</Data>
<Data>
</Data>
<Data>
</Data> <Binary>0000000007002C00000000001C000080000000000000000000000000000000000000000000000000</Binary>
</EventData>
</Event>
You are a lifesaver. I was beating my head against a wall until I saw your post. Fixed the problem immediately! Thanks!!!!
Thank you for this.
Yes this worked for me too, when doing a P2V with VMM2008, it set the NIC on the virtual guest to static and it was the same as the physical server which was P2V’d from. Still having the source server running, it was conflicting with the MAC address. I changed it from static to dynamic and it has fixed the issue.
No problem, Glad it helped! 🙂
I’m having a similar problem and would love to see how you corrected it, but for some reason your site isn’t displaying the article. Oh no!