Article ID: 125835, created on Jun 11, 2015, last review on Jun 11, 2015

  • Applies to:
  • Virtuozzo 6.0


Massive multicast traffic can be detected from a PCS server after starting a virtual machine with Windows OS installed in it. The issue occurs only on Windows VMs, not on Linux VMs, nor on CTs.

This issue can be observed after booting the host server to one of the following kernels:

  • 2.6.32-042stab102.9
  • 2.6.32-042stab103.4
  • 2.6.32-042stab104.1


Kernels 2.6.32-042stab102.x-2.6.32-042stab104.x are based on a Red Hat kernel 2.6.32-504.el6, which introduces a lot of changes to the network bridges code. Multicast packets are forwarded without BR_ALREADY_SEEN flag, that is why this traffic can be amplified by bridges.

Issue is recognized as a product bug with internal ID #PSBM-31496.


Issue is fixed starting from kernel 2.6.32-042stab105.14.
Install kernel updates on a hardware node to mitigate the issue.

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