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TJF
Asked: 2016-04-28 11:52:33 +0800 CST

Hyper-V Windows hosts see/count multicast traffic that they shouldn't

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I have some of my Hyper-V VM's on a network segment that pushes a lot of UDP multicast traffic (several 100MBit/s).

Now, all Hyper-V Windows hosts actually see and count the traffic on the Ethernet ports without joining the multicast group. I can even capture the traffic with Wireshark without having joined the multicast group. This means, Hyper-V must pass the traffic to the NIC driver when the traffic should be ignored by the NIC itself.

On my ESXi VM's this is not the case - the MCAST traffing is only seen when the host joins the multicast group and some goes for bare metal hosts.

Any idea why/what Hyper-V is doing here and if this behavior can be changed?

hyper-v multicast windows-server-2012-r2

1 Answers

  1. Best Answer

    If you're using a NIC that doesn't support VMQ, or if you have VMQ disabled, then the NIC must be placed in promiscuous mode, which leads to the behavior that you're seeing.

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