+-----+ +-----+ +-----+ +-----+ | | | | | | | | | EE |<---------->| LRA |<-------------->| RA |<---------->| CA | | | | | | | | | +-----+ +-----+ +-----+ +-----+ synchronous (a)synchronous (a)synchronous +----connection----+------connection------+----connection----+ operators service partner +---------on site---------+---back-end services--+---trust center--+ <--- downstream <--- | ---> upstream --->