Which KNX/IP interface are you using? Does it support Routing or Tunneling?
This (Physical Address) PA (15.15.254) is the factory default one for the KNX/IP interface. In theory, you should change (with ETS).
For the localSourceAddr you should set a free PA in your BUS (if using Router) or one from the pool that the Tunneling interface provides (usually they provide up to 4)
This localSourceAddr will “represent” the openHAB system in the KNX Bus
By default, it is set to 0.0.0. Try this for now and see if it works as is.
This is the PA of one of your KNX Actuators (switch, rollershutter, dimmer, etc)
If you have ETS access to it, then you can make it work in OH2 also 