1. A method comprising: representing a routing table for a data network as a binary search tree of address prefixes ordered by prefix lengths, the binary search tree having a root node and two subtrees of nodes including parent nodes and descendant nodes disposed in hierarchical levels of the subtrees, the descendant nodes comprising leaf nodes; placing respective markers in the parent nodes to guide accessing the descendant nodes in the subtrees to search for a destination address of a data packet; associating destination descendant nodes with the markers, the destination descendant nodes being separated from the parent nodes by at least one intermediate hierarchical level; traversing the binary search tree in a direction from the root node to the leaf nodes to determine a longest prefix match between the markers and the destination address, wherein traversing the binary search tree comprises accessing the respective destination descendant nodes while avoiding accessing the descendant nodes of the at least one intermediate hierarchical level; and processing the data packet in the data network in accordance with an entry in the routing table that corresponds to the longest prefix match, wherein associating destination descendant nodes comprises: making a first determination that compatible descendant nodes in a selected subtree comprise address prefixes that are compatible with the marker of one of the parent nodes; making a second determination that one of the compatible descendant nodes is a leaf node or has additional compatible descendant nodes; and responsively to the second determination assigning the one compatible descendant node as the destination descendant node.