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 packet 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