MULTOPS implementation

MULTOPS is implemented using Click [KMC$^+$00]. Click is a modular software router architecture developed at the MIT Laboratory for Computer Science. A Click router is an interconnected collection of modules called elements. Each element performs a simple, straightforward task such as communicating with devices, queueing packets, and implementing a dropping policy. Each element has 0 or more inputs and 0 or more outputs. Inputs are used to receive packets from other elements. Outputs are used to hand off packets to other elements. Configuration of a Click router is done by feeding it a file describing which elements to use and how the inputs and outputs of these elements interconnect.

MULTOPS is implemented as 2 separate elements: IPRateMonitor and RatioBlocker. Adding these elements to the configuration adds the MULTOPS detection mechanism and the related dropping policy to the router. IPRateMonitor tags each packet with from-rate and to-rate such that RatioBlocker may decide to drop the packet based on these tags and based on the defined thresholds (i.e., $R_{min}$ and $R_{max}$). Thus, IPRateMonitor implements the tree, RatioBlocker implements a dropping policy based on the MULTOPS detection heuristic.

IPRateMonitor has 2 inputs and 2 outputs. Each input should be connected to a different physical network interface. RatioBlocker has 1 input and 1 output.