Why running “configure-firstnet” must not be run twice (ODA)

Recently I was deplyoing some Oracle Database Appliances X7-2M at a customers site. Everything went quite smooth until we tried to configure the network using “configure-firstnet”. The documentation is quite clear about this, one shall not run this more than once. But in our case we first configured the network without VLANs which ended up with a nice “ifcfg-btbond1” configuration containing the IP information.
But as we figured out we had to use a VLAN so we simply run “configure-firstnet” again. This generated an “ifcfg-btbond1.26” configuration file for our VLAN with ID 26. It had the same IP information in it as the one without VLANs. This works fine since the script is obviously creating the interfaces properly.
But after a

service network restart

The machine was not reachable anymore. As we investigated this, we saw that there are now two bond interfaces with a configured IP which obviously prevents any network communication.

So the solution was to remove all lines/parameters from “ifcfg-btbond1” configuration file, that were IP-related and restart the network again. At the end the issue was quite obvious and easy to remedy but it took us some time which could have been used better. That emphasizes the importance of clear information and a well structured preparation when deplyoing an Oracle Database Appliance (and other appliances too).