I. Introduction
At the heart of any Internet router lies a so-called Forwarding Information Base (FIB) containing the router's forwarding rules. A routing decision for a given packet is made on the basis of these rules and the destination IP address of a packet. A fast rule lookup requires the FIB to be stored in a fast (and expensive) memory on the line cards. Nowadays, the number of these rules at the Internet core routers is growing at an alarming rate. New forwarding rules emerge primarily because of the growth of the Internet itself, trends for advertising more specific routes, or the increasing demand for virtual networks [4], [12]. The migration to IPv6 is not expected to mitigate the address space disaggregation problem [5]. The increasing memory requirement comes at a significant cost for ISPs, as this memory is expensive and power-hungry.