Multiclass AQM on TCP/IP Routers: Modeling, Analysis, and Design

Active Queue Management (AQM) is implemented in routers to manage network congestion. It is designed to detect network congestion and control the rate of packet transmission by dropping or marking packets in the buffer memory of the router. By doing this, it notifies the Transmission Control Protocol (TCP) sources about the state of the network and helps prevent congestion from further escalating. The chapter addresses the limitations of previous works on AQM, which assumed homogeneous traffic and did not account for the different requirements and characteristics of diverse types of traffic. The chapter highlights that in real-world scenarios, heterogeneous traffic exists, and it is essential to differentiate among them based on their specificities such as security (e.g., e-banking transfers and financial), delay, bandwidth, loss rate (e.g., VoIP), and what’s not special specifications (such as normal email traffic). Therefore, the chapter surveys the AQM problem with an emphasis on accommodating multiple traffic classes with different specificities, i.e., heterogeneous traffic. In order to demonstrate the effectiveness of the proposed methodology in handling heterogeneous traffic in a congested router, we present simulation results involving three different classes of traffic. Each class of traffic may have different queue sizes, bandwidth shares, and discarding policies, illustrating the advantages of tailoring AQM mechanisms to the specific needs of different types of traffic.