Figure 6

A planar network (a) and non-planar one with intersecting links (b). A packet is trying to reach the sink while in azimuth state, from the node Y. The first hop is the node B. Then, keeping the clockwise forwarding direction, the next hops are chosen. In the planar network, the packet eventually reaches the sink. In the non-planar one, the packet from the node B will be forwarded to A, because ∟YBA < ∟YBD < ∟YBE < ∟YBX and the node D, being the only way to the sink, does not lie on the hole border. Note, that the forwarding direction which is clockwise around the hole means the counter-clockwise calculation of the azimuth angles (see also Figure 5) and the counter-clockwise circulation around a part of the network. As a result, the packet will remain circulating in a loop.