+-------------+                            +---------------+
        |             |<-(1)--- DOTS signal ------>|               |
        |             |      channel session 1     |               |
        |             |<=(2)== redirect to B ======|               |
        | DOTS client |                            | DOTS server A |
        |             |X-(4)--- DOTS signal ------X|               |
        |             |      channel session 1     |               |
        |             |                            |               |
        +-------------+                            +---------------+
               ^
               |
              (3) DOTS signal channel
               |      session 2
               v
        +---------------+
        | DOTS server B |
        +---------------+