UniLoG: A Unified Load Generation Tool

Motivation

Utilities for generating artificial (synthetic) loads are very important for analyses of performance and behavior of networks and their offered services. Load generators implemented by the industry are mainly dedicated hardware components with very high performance and stringent precision requirements. In research and academia, mainly software based load generators are commonly used because of the expected higher flexibility in operation and maintenance (e.g. due to easy deployment of constituent load generating modules in the network, code customizations for a specific research purpose, etc.) while components of real operating systems and protocol stacks can be used to guarantee realistic load generation at lower costs. However, many existing tools are dedicated to a specific modeling study (e.g., Guernica [1] along with its specific Dweb model for Web traffic, or Harpoon [2] modeling IP traffic flows) or are focusing on generating traffic at some specific interface in a network (e.g., ITG [3] or Brute [4] were designed to generate traffic on UDP and TCP service interfaces). The proposed solutions quite often do not provide an adequate flexibility, e.g. in case the underlying model is to be modified or a completely new model is to be used. Therefore, the unified load generator UniLoG is presented in this paper, which combines the specification and generation of network loads in one single coherent approach. The basic principle underlying the design and elaboration of UniLoG is to start with a formal description of an abstract load model by means of a finite user behavior automaton (UBA, introduced in Sec. 2) and thereafter to use interface-specific adapters to map the abstract requests to the concrete requests as they are “understood” by the service providing component at the real interface in question. An overview of the distributed UniLoG architecture is given in Sec. 3 and a concrete example of its practical use in QoS studies for video streaming is demonstrated in Sec. 4.