In order to overcome the void area problems faced in VBF, Vector Based Void Avoidance (VBVA) is proposed in . VBVA has capability to detect a void and bypass it on demand, hence it does not need to keep record of topology information. Void avoidance is realized using two mechanisms: vector-shift and back pressure. Void is detected if a node finds no neighbour with “advance” greater than its own “advance”. Vector shift method allows nodes out of routing pipe to forward the packet and hence a shifted vector is formed. If a node cannot find neighbours to shift; it broadcasts a back pressure packet to reroute the packet with better path which has no void. However void detection process is only capable to detect it on the edge of the network and has no solution if void occurs in middle of networks due to unexpected deaths of intermediate nodes. Moreover backward flooding would cause extra over head especially in sparse networks. The performance of these protocols can be improved by identifying critical (i.e., cut-vertices) and non-critical nodes in the network using any of the algorithm such as .