An Analysis of the Hardware-Friendliness of AMQ Data Structures for Network Security.

Field-programmable gate arrays (FPGA) are increasingly used in network security applications for high-throughput measurement solutions and attack detection systems. One class of algorithms that are heavily used for these purposes, are approximate membership query (AMQ) data structures, which provide a mechanism to check, with a certain false positive rate, if an element is present in the data structure or not. AMQ data structures are used, for example, in distributed denial-of-service (DDoS) attack detection. They are typically designed to work efficiently on general-purpose processors, but when the high throughput of FPGAs is required, hardware-friendly implementations of AMQ modules are indispensable. A hardware-unfriendly AMQ module would considerably slow down the overall system and compromise the security when it is required to operate at line rate in a high-bandwidth network. Hence, choosing a suitable data structure and hardware architecture is of utmost importance. In this work, we propose FPGA architectures for various well-known AMQ data structures and analyze their hardware implementation properties. This work serves as a guideline on FPGA-based AMQ architectures for researchers and practitioners working on high-throughput network security applications on FPGA.