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jrmunday
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Multicast storm - Quad port NC375T gigabit adapter

Hi All,

Has anyone seen any weird issues in an vSphere environment where a vmnic port spews out excessive multicast traffic for no apparent reason?

We've had an issue where a multicast storm caused fairly significant impact by taking down some switch stacks (and all the services connected to them). The observed behavior was that one vmnic spewed out ~30k multicast packets per second despite there being no VM's using these uplinks. Dropping the port (at the switch end) and bringing it back online again made no difference. A simple host reboot however resolved the issue. We've not taken any chances and replaced the quad port NIC (incase it's faulty), but would really like to understand the root cause.

Does anyone have experience of this, or perhaps seen something similar?

Any pointers appreciated.

Thanks,

Jon

vExpert 2014 - 2022 | VCP6-DCV | http://www.jonmunday.net | @JonMunday77
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Gortee
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I have seen this before and in every case it was a faulty card that would not die silently.  It just had to be loud Smiley Happy

Joseph Griffiths http://blog.jgriffiths.org @Gortees VCDX-DCV #143