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On my ESXi 3.5 servers, I occasionally see a problem where - on newly started VMs - I see no traffic at all on their virtual network interfaces. I have to go into the VM settings and remove, then re-add the network interfaces before I see any traffic.

Has anyone seen this before? Is it possible I need to configure my physical switches (Cisco) differently to support this?

I'm using portgroups to present VLAN traffic to VMs - I've seen this happen on both trunked and untrunked ports, if that matters.

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I have seen this before.

When I edit the settings and click on the network adapter, the Connect at power on is checked but not the Connected. So far all I needed to do was to check the Connected box and the interface will come up.

I have not seen this on ESXi 4 yet, but will keep an eye out. Maybe it is related to the adapter type.

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I'll check these settings next time I see the problem. Good to hear it may be ok in ESXi4 though. – Jon Topper Jul 21 '09 at 15:14

Here's a theory.

You have VMotion enabled and the machine migrated to a host where the network that it was linked to do not exist.

When you now remove and add a network adapter, it picks up "VM Network" which works.

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We're not using VMotion here. – Jon Topper Jul 21 '09 at 15:13

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