Mobile routers establish a tree-based network topology in an ad hoc mobile
network, the tree-based network topology having a single clusterhead and
attached mobile routers. Each attached mobile router has a default egress
interface configured for sending messages toward the clusterhead, and
ingress interfaces configured for receiving messages from attached
network nodes that are away from the clusterhead. A neighbor
advertisement message received from an ingress interface away from a
clusterhead is used by the attached mobile router to identify specified
network prefixes that are reachable via the source of the neighbor
advertisement message. The attached mobile router outputs on its default
upstream interface a second neighbor advertisement message that specifies
the network prefix used by the attached mobile router, and the specified
network prefixes from the neighbor advertisement message received on the
ingress interface. Hence, connectivity is established with minimal
routing overhead.