A Requirement Aware Method to Reduce Complexity in Selecting and Composing Functional-Block-Based Protocol Graphs Daniel Günther, Nathan Kerr, and Paul Müller Integrated Communication Systems (ICSY) University of Kaiserslautern Kaiserslautern, Germany {guenther,kerr,pmueller}@informatik.uni-kl.de Abstract. Future Internet research activities try to increase the flexi- bility of the Internet. A well known approach is to build protocol graphs by connecting functional blocks together. The protocol graph that should be used is the one most suitable to the application’s requirements. To find the most suitable graph, all possible protocol graphs must be evalu- ated. However, the number of possible protocol graphs increases exponen- tially as the number of functional blocks increases. This paper presents a method of representing the protocol graph search space as a set of search trees and then uses forward pruning to reduce the number of protocol graphs evaluated. We evaluate our proposed method by simulation. Keywords: future network, composition, complexity, protocol graph. 1 Introduction In the current ISO/OSI stack model of the Internet, protocols dictate the avail- ability and composition of network functionality. A flexible architecture, as often discussed in the Future Internet research area, will be able to support the desire to dynamically choose certain mechanisms based on the requirements of a par- ticular application. In the 90s many approaches dealt with flexible configurations or functional modules. This idea was the vision for projects like Adaptive [3], DaCaPo [8], and FCSS [6]. More recent projects with similar goals are 4WARD [9,11], NENA [10] and SONATE [2]. This research has grown into a big scientific area. The research seeks to provide domain specific network compositions, more flexibility through functional composition and application aware compositions. In general, the basis for providing this functionality consists of functional blocks, which represent network functionality and are combined into protocol graphs. These approaches generally work in the way shown in Figure 1. An applica- tion provides its requirements which are combined with network offers and any addition criteria from the system. A selection and composition system draws from a pool of functional blocks to create a protocol graph which fulfills the application’s requirements. R. Benlamri (Ed.): NDT 2012, Part I, CCIS 293, pp. 399–407, 2012. c  Springer-Verlag Berlin Heidelberg 2012