Ongoing transfers    New transfer requests
                             \----\        |
                                  |        |
                                  v        v
   +-------------+               +---------------+
   | ALTO Client | <===========> | Data Transfer |
   +-------------+               |   Scheduler   |
     ^ |      ^ | PV Request     +---------------+
     | |      | \--------------\
     | |      \--------------\ |
     | v       PV Response   | v
   +-------------+          +-------------+
   | ALTO Server |          | ALTO Server |
   +-------------+          +-------------+
         ||                       ||
     +---------+              +---------+
     | Network |              | Network |
     | Manager |              | Manager |
     +---------+              +---------+
      .                           .
     .             _~_  __         . . .
    .             (   )(  )             .___
  ~v~v~       /--(         )------------(   )
 (     )-----/    (       )            (     )
  ~w~w~            ~^~^~^~              ~v~v~
 Site 1        Non-blocking Core        Site 2