Prefix Compression To Reduce Overhead Associated with Covering Routes

原文（中文）

A network device uses prefix compression to program routes in a forwarding information base (FIB) in a longest prefix match (LPM) table or an exact match (EM) table. The network device compresses routes of a certain prefix length in the FIB into a single entry in the EM table. For a compressed prefix that does not correspond to a route in the FIB (hole), the network device associates the hole with a special value rather than the prefix of a covering route. When the network device receives a packet that matches a hole, the lookup performed on the exact match table results in the special value. In response, the network device uses the result of the lookup performed on the LPM table to determine how to forward the packet.