Summary
This event indicates that one or more portgroups in the ESX host have lost connectivity to the network, resulting in unavailability of all physical connections to the network from this switch.
Example
If vmnic1 is the only uplink on vSwitch0 and VM Network is the only portgroup connected to this virtual switch, then this error occurs if vmnic1 goes down:
Lost network connectivity on virtual switch "vSwitch0". Physical NIC vmnic1 is down. Affected portgroups: "VM Network"
Impact
The services associated with the affected portgroups are disconnected from the associated physical networks: virtual machines, service console, VMotion, NFS, iSCSI, and Management Services.