Algorhyme

  I think that I shall never see
  A graph more lovely than a tree.
  A tree whose crucial property
  Is loop-free connectivity.
  A tree that must be sure to span
  So packets can reach every LAN.
  First, the root must be selected.
  By ID, it is elected.
  Least-cost paths from root are traced.
  In the tree, these paths are placed.
  A mesh is made by folks like me,
  Then bridges find a spanning tree.
  -Radia Perlman