15.1 A 0.795fJ/bit Physically-Unclonable Function-Protected TCAM for a Software-Defined Networking Switch

As IoT devices proliferate, it is necessary to pay attention to how they interact within heterogeneous networks, where the packet type, protocol, and bandwidth vary. Software-defined networking (SDN) is increasingly used because of its flexibility, which adapts to different types of applications by customizing the flow rules in switches. Ternary content addressable memory (TCAM) is a key component of the SDN switch and collects all routing flow rules [1–5]. During a routine procedure, TCAM supports parallel comparison between an incoming packet and stored existing flow rules, to find the matching path within a clock cycle. However, deploying traditional TCAMs on SDN systems encounters three challenges as illustrated in Fig. 15.1.1: (1) TCAM suffers from high-power consumption because the entire array is activated for each search, and the bit cell is area inefficient, as it uses independent storage (6T) and comparison (2T~4T) transistors. (2) TCAM requires long latency to update stored rules and mismatches the update latency requirements of network protocols. If multiple rules match during a search, then the rule with the highest priority is returned. Therefore, when adding a new rule an empty entry, in the existing priority sequence, needs to be made, requiring the movement of all lower priority rules. (3) TCAM is vulnerable to routing-related attacks. Without sophisticated identification techniques, an attacker can counterfeit a malicious node and advertise a shorter routing path to attract traffic, and then alter or drop packets.