+----------------+
      | session-sender |
      +----------------+  0..* +---------------------------+
      | admin-state    |<>-----| test-session              |
      +----------------+       +---------------------------+
                               | name                      |
                               | ctrl-connection-name {ro} |
                               | fill-mode                 |
                               | number-of-packets         |
                               | state                {ro} |
                               | sent-packets         {ro} |
                               | rcv-packets          {ro} |
                               | last-sent-seq        {ro} |
                               | last-rcv-seq         {ro} |
                               +---------------------------+
                                            ^
                                            V
                                            | 1
                                +---------------------+
                                | packet-distribution |
                                +---------------------+
                                | periodic / poisson  |
                                +---------------------+
                                    |           |
                         +-------------------+  |
                         | periodic-interval |  | 
                         +-------------------+  |
                                                |
                                        +--------------+
                                        | lambda       | 
                                        | max-interval |
                                        +--------------+