Comment 2 for bug 425914

In SYSTEM mode, Eucalypus connects instances to the existing LAN by way of a bridge, and relies on existing networking infrastructure (DHCP servers, DNS, etc.) to run them. This is a very basic mode of operation, and is somewhat limited. In MANAGED(-NOVLAN) you get all the bells and whistles Eucalyptus has to offer: EBS, Elastic IP's, the user-data and meta-data service, etc. So much for the rationale.

In order to get into MANAGED(-NOVLAN) mode, Eucalyptus needs to have a dedicated subnet for its instances. I've added debconf questions to get networking information from the admin and changed a bit of logic along the way to make Eucalyptus use these settings. In this mode, Eucalyptus will run a few extra services, which will only be exposed to Eucalyptus' internal subnet.