_____    __             _____    __             _____    __
  __(     )__(  )_        __(     )__(  )_        __(     )__(  )_
 (    Network a   )      (    Network b   )      (    Network c   )
( Res. Provider A  )    ( Res. Provider B  )    ( Res. Provider C  )
 (__ ALTO_SRV_A __)      (__ ALTO_SRV_B __)      (__ ALTO_SRV_C __)
   (___)--(____) \         (___)--(____)         / (___)--(____)
                  \           /                 /
                ---+---------+-----------------+----
               (              Backbone              )
                ------------+------------------+----
                _____    __/            _____   \__
             __(     )__(  )_        __(     )__(  )_
            (    Network x   )      (    Network t   )
           ( Res. Consumer X  )    (Resource Directory)
            (_  ALTO_SRV_X __)      (_  ALTO_SRV_T __)
              (___)--(____)           (___)--(____)