Currently I’m working on a customer install where we are using the new vsphere 5.0 vcenter server appliance. As we were migrating an existing 3.5 environment to a new platform, we had to keep adding and removing servers in and out of vCenter due to the limitations of the appliance.
On one occasion we had to remove the new vCenter appliance from the inventory of one server and add it to the inventory of another. When this happened, the appliance found added a new NIC (eth1) and would not function as it said eth0 was not connected and the appliance is only configured to used eth0.
If you ever get this error, there is a simple fix.
Log onto the vCenter appliance (via the console) and log in as root, for the vCenter appliance the username is root and the password VMware. Edit the file (using vi) /etc/udev/rules.d/70-net-persistent-names.rules.
This file shows all the network interfaces and their associated MAC addresses. Simply remove the entry for eth0 and edit the line for eth1, renaming it to eth0. Save the file with the command :wq and restart the server using shutdown –r now.