docs/mi02.aa

   1     +---------+     +---------+     +---------+
   2     |Server S1|     |Server S2|     |Server S3|
   3     +---------+     +---------+     +---------+
   4     |    A    |     |    A    |     |    A    |
   5     |cGRE     |<----+cRED     +---->|cGRE     |
   6     +---------+     +---------+     +---------+
   7     |    B    |     |    B    |     |    P    |
   8     |cGRE     |<----+cRED     |     |         |
   9     +---------+     +---------+     +---------+
  10     |    L    |     |    C    |     |    C    |
  11     |         |     |cGRE     |<----+cRED     |
  12     +---------+     +---------+     +---------+
  13     |    M    |     |    D    |     |    D    |
  14     |         |  +->|cGRE     |     |cGRE     |<--+
  15     +---------+  |  +---------+     +---------+   |
  16     |    D    +--+  |    E    |     |    E    |   |
  17     |cRED     |  |  |cRED     +---->|cGRE     |   |
  18     +---------+  |  +---------+     +---------+   |
  19                  |                                |
  20                  +--------------------------------+