While source routing a data packet, when an MN wants to forward it to the next hop address in the source route, it checks whether the next hop is one of its neighbours. This is done by checking in the link cache, which is explained in the section below. If so, the packet is forwarded, else a Route Error packet is sent back to the source. This route error provides information as to which link has broken. When the source receives the Route Error packet, it removes all the paths in its route cache that contain this link. It also removes the link from its link graph, which is explained in Section 3.6.