As the evolution of living species is determined by few basic mechanisms, such as genetic heritage, genetic variation, and natural selection, it may be that the evolution of large-scale internetworks is similarly determined by some simple, but still unknown, principles. The proposed research aims to discover the fundamental character of network evolution, the laws that describe it, and ways in which networking researchers or innovators can influence this process most effectively.

The proposed research consists of two threads that will proceed in parallel. They are both related to network evolution, but they focus on different aspects of that process. Specifically, in the first research thread the focus is on the evolution of the Internet Autonomous System (AS) ecosystem. In the second research thread, the focus is on the evolution of network design and architecture.

1. The evolution of the AS ecosystem: The Internet, as a network of Autonomous Systems, resembles in several ways a natural ecosystem. ASes of different sizes, functions, and business objectives form a number of AS ``species'' that interact to jointly form what we know as the global Internet. ASes engage in competitive transit relations, and also in symbiotic peering relations. These relations, which are represented as inter-AS logical links, transfer not only traffic but also economic value between ASes. The Internet AS ecosystem is highly dynamic, experiencing growth (birth of new ASes), rewiring (changes in the connectivity of existing ASes), as well as deaths. The dynamics of the AS ecosystem are determined both by external ``environmental'' factors and by the incentives and objectives of each AS. Specifically, ASes attempt to optimize their utility or financial gains by dynamically changing, directly or indirectly, the ASes they interact with. The first part of the proposed research is motivated by the desire to better understand this complex ecosystem, the behavior of entities that constitute it, and the nature of interactions between those entities.

2. The evolution of network design and architecture: In the second research thread we will focus on the laws or principles that determine the evolution of large-scale internetworks. What is the price of evolution, i.e., the relative cost of a network that evolved to meet some objectives compared to an optimal network designed to meet the same objectives? When is it better to abandon an existing network architecture and start over with a clean-slate design? How does an evolutionary network compare to a clean-slate design in terms of robustness in an uncertain and dynamic environment? Which are the evolutionary implications of layered network design and why does it appear that the middle layers (the protocol waist) get stable (``ossified'') first? The motivation for this second research thread is not only to understand the evolution of the current Internet, but also to provide concrete guidelines for the design of evolvable architectures for the Future Internet (through NSF's FIND or ICT's FIRE programs, for instance).