Energy‐Aware Controller Placement With Delay Guarantees for In‐Band SDN

Software‐defined networking (SDN) enables flexible, programmable networks, but in large deployments, poor controller placement can raise latency and energy use. This paper presents a practical in‐band SDN model and an optimization method that jointly accounts for control‐plane delay and device power consumption to place controllers and configure switches. We formulate the problem as a binary integer programming (BIP) that decides controller locations, which switches remain active, and port bit‐rates and routes. Experiments on a large WAN topology (Janos‐US) show the approach can cut total network energy by up to 15% while keeping control‐plane delays within required bounds, offering network operators a straightforward way to trade responsiveness for energy savings.