A method, comprising: selecting a subset of nodes in a computer network as region anchor nodes, each region anchor node associated with a respective one of a plurality of regions of the computer network; and discovering a route to a target node in a particular region of the computer network by a process comprising: receiving, at a given region anchor node of the computer network, a route request, RREQ, for the target node, the RREQ having been unicast by an originator node of the computer network to the region anchor node via a unicast route, the region anchor node configured to communicate with the originator node and a given one of the plurality of regions of the computer network, the given region comprising one or more nodes proximate to the region anchor node; flooding the RREQ to the region; receiving, at the region anchor node, one or more reactive routing route replies, RREPs, returned by the target node in the region; building, at the region anchor node, based on the RREPs, one or more region routes from the region anchor node to the target node; and returning the one or more region routes from the region anchor node to the originator node to cause the originator node to concatenate the one or more region routes and the unicast route to form a path from the originator node to the target node; wherein the plurality of regions comprise overlapping regions such that given nodes are covered by two or more regions; and wherein discovering a route to a node comprises sending a RREQ to a region anchor node in a first region and, in response to not receiving a RREP after a given time, sending a further RREQ to another region. selecting a subset of nodes in a computer network as region anchor nodes, each region anchor node associated with a respective one of a plurality of regions of the computer network; and discovering a route to a target node in a particular region of the computer network by a process comprising: receiving, at a given region anchor node of the computer network, a route request, RREQ, for the target node, the RREQ having been unicast by an originator node of the computer network to the region anchor node via a unicast route, the region anchor node configured to communicate with the originator node and a given one of the plurality of regions of the computer network, the given region comprising one or more nodes proximate to the region anchor node; flooding the RREQ to the region; receiving, at the region anchor node, one or more reactive routing route replies, RREPs, returned by the target node in the region; building, at the region anchor node, based on the RREPs, one or more region routes from the region anchor node to the target node; and returning the one or more region routes from the region anchor node to the originator node to cause the originator node to concatenate the one or more region routes and the unicast route to form a path from the originator node to the target node; wherein the plurality of regions comprise overlapping regions such that given nodes are covered by two or more regions; and wherein discovering a route to a node comprises sending a RREQ to a region anchor node in a first region and, in response to not receiving a RREP after a given time, sending a further RREQ to another region. receiving, at a given region anchor node of the computer network, a route request, RREQ, for the target node, the RREQ having been unicast by an originator node of the computer network to the region anchor node via a unicast route, the region anchor node configured to communicate with the originator node and a given one of the plurality of regions of the computer network, the given region comprising one or more nodes proximate to the region anchor node; flooding the RREQ to the region; receiving, at the region anchor node, one or more reactive routing route replies, RREPs, returned by the target node in the region; building, at the region anchor node, based on the RREPs, one or more region routes from the region anchor node to the target node; and returning the one or more region routes from the region anchor node to the originator node to cause the originator node to concatenate the one or more region routes and the unicast route to form a path from the originator node to the target node; wherein the plurality of regions comprise overlapping regions such that given nodes are covered by two or more regions; and wherein discovering a route to a node comprises sending a RREQ to a region anchor node in a first region and, in response to not receiving a RREP after a given time, sending a further RREQ to another region.