Sharing One Physical Interface With Multiple Realms

Hello,

 

Please excuse my ignorance but I'm a novice with SD and need some guidance on configuring one physical interface to support three different Realms serviced by the same service provider.  Each are on the same subnet. From what I've researched so far this can be accomphlished by configuring the Network interfaces for the Realms with different sub port ids(Vlans).  I get this part but want to ensure I'm not missing anything, is this all thats needed can someone confirm this? I'm assumming the sub port examples below will create the logical vlans and separate the traffic intended for each Realm.