A few of our clients started to have strange network connection issues starting a few months ago at random times. I wanted to see if anyone is having the same issue or could shed some light into what is going on. We have a consistent setup among our client this is only happening to a few. Thanks!
Either both the Hyper-V host and the VM's will lose network connection (internet and LAN communication) or just some of the VM's.
- All servers are Dell's with 2 Broadcom Network Adapters. Network Driver/firmware and Windows updates are up to date with latest.
- All servers are using Teamed Adapters in Switch Independent mode and dynamic load balancing
- HyperV host shares vSwitch for ManagementOS and VM’s
- Basic out of the box Hyper-V setup and not clustering
- Some or all VM’s will lose network communication with other servers, desktops and the internet
- The network adapters on the Host and VM’s don’t display any issues right away and eventually will say no internet access
- Hyper-V host is unable to ping default gateway, the VM’s, or any public IP address. Team and both NIC’s do not display any issues are show as up. At times, I am still able to initial a remote connection to the HV host even though the HV host can’t communicate to the internet and can’t ping the gateway.
I am able to resolve the issue by disabling one of the network adapters and re-enabling. Network communication comes back.
The only thing I can see in the event log in the following Event
Log Name: System
Date: 7/14/2015 9:54:55 AM
Event ID: 16945
Task Category: None
MAC conflict: A port on the virtual switch has the same MAC as one of the underlying team members on Team Nic Microsoft Network Adapter Multiplexor Driver
Running a Get-NetAdapater shows that there are the same MAC addresses however, other servers that are working fine show the same. I manually set all of the MAC addresses to something different but still get the event log entry and still have the same issue.
Name InterfaceDescription ifIndex Status MacAddress LinkSpeed
---- -------------------- ------- ------ ---------- ---------
NIC1 Broadcom NetXtreme Gigabit Ethernet #2 13 Up F8-BC-12-4D-35-AE 1 Gbps
vEthernet (SWITCH-01) Hyper-V Virtual Ethernet Adapter #2 21 Up F8-BC-12-4D-35-AE 10 Gbps
Hyper-V Team Microsoft Network Adapter Multiplexo... 18 Up F8-BC-12-4D-35-AE 2 Gbps
NIC2 Broadcom NetXtreme Gigabit Ethernet 12 Up F8-BC-12-4D-35-B0 1 Gbps