Method for increasing average storage capacity in a bit-mapped tree-based storage engine by using remappable prefix representations and a run-length encoding scheme that defines multi-length fields to compactly store ip prefixes

Abstract

Sparsely distributed prefixes within a bitmapped multi-bit trie are compressed by one or more of: replacing a single entry table string terminating with a single prefix end node with a parent table entry explicitly encoding a prefix portion; replacing a table with only two end nodes or only an end node and an internal node with a single parent table entry explicitly encoding prefix portions; replacing two end nodes with a single compressed child entry at a table location normally occupied by an internal node and explicitly encoding prefix portions; and replacing a plurality of end nodes with a prefix-only entry located at the table end explicitly encoding portions of a plurality of prefixes. The compressed child entry and the prefix-only entry, if present, are read by default each time the table is searched. Run length encoding allows variable length prefix portions to be encoded.