In general, techniques are described for summarizing label mappings and thereby enabling longest-prefix match within Multi-Protocol Label Switching (MPLS) networks. More specifically, a first router included within a first area of a network comprises a control unit that maintains a label space defining labels available for mapping to a plurality of addresses assigned to network devices within the network. The control unit reserves a contiguous set of the labels of the label space and maps the contiguous set of labels to first area addresses. The first area addresses include those addresses of the plurality of addresses available for assignment to network devices within the first area. The first router also includes an interface card that transmits, to a second router of a second area of the network, an advertisement that advertises a summarized version of the mapping between the contiguous set of labels and the first area addresses.