It is a modified version of the tree network. In this group the bandwidth of edge (or the connecting wire among nodes) increases towards the root. It is a more practical simulation of the normal tree where branches get thicker towards root. It is the more well-liked as compared to tree structure, as practically the more traffic arise towards the root as compared to leaves, thus if bandwidth remains the similar the root will be a bottleneck causing more late. In a tree this problem is avoided because of high bandwidth.